By the way, I would like to recommend a book. I have already recommended
this book on this list before, but this time I want to recommend it
specifically to Mostafa because he just keeps repeating that watchmaker
fallacy that I clearly showed to be circular logic. It has been years
since I read this book, but I remember clearly that it does address
Mostafa's fallacy. It is The Blind Watchmaker by Richard Dawkins. The
watchmaker in the title does refer to William Paley's watchmaker and
Dawkins does an excellent job of refuting that fallacy. However, the
subject of the book is not in its entirety a book about the watchmaker
fallacy. After all, I refuted it pretty well in a single email. So it
would be kind of silly to devote an entire book to just that point. What
the book is all about is, for one thing, showing how highly complex
systems can arise out of very simple beginnings without any conscious
intervention. But Dawkins is a professional evolutionary biologist. Back
when I was reading those journals in the basement of my college's
library I think I remember reading some of his peer reviewed papers on
the subject. So the highly complex system he concentrates on in The
Blind Watchmaker is biological evolution. In fact, the real subject of
the book is how evolution works. If Mostafa is serious about his
questions about how something as complex as the biological world could
arise from the so-called primordial soup then the answer is right there
in that book. I should point out that even though Dawkins is a
professional evolutionary biologist this book is not very technical. It
was written especially for a lay audience.
---
Carl Sagan
??? Extraordinary claims require extraordinary evidence. ???
??? Carl Sagan
On 6/6/2019 8:48 PM, Roger Loran Bailey (Redacted sender rogerbailey81
for DMARC) wrote:
Okay, I just posted a few articles about the actual observation of evolution in progress. I found them with a simple Google search. I got tens of thousands of results and I don't have the time to post all of them and I am sure that the rest of you do not have the patience to read all of them. What I have already posted is plenty sufficient to show that Mostafa does not know what he is talking about. If any of you are interested in the subject I would urge you to visit TalkOrigins.org or just do some Googling around yourselves. To be honest, though, I sometimes feel a bit embarrassed for Mostafa.
---
Carl Sagan
??? Extraordinary claims require extraordinary evidence. ???
????? Carl Sagan
On 6/6/2019 8:39 PM, Roger Loran Bailey (Redacted sender rogerbailey81 for DMARC) wrote:http://www.bio.miami.edu/dana/160/160S13_4.html
The Fact of Evolution: Observable Evidence
??Despite what some might believe, the physical evidence that evolution has happened is overwhelming. This might not have been the case in Darwin's time. But since the publication of On the Origin of Species, a great deal more has come to light.
There are at least four major lines of physical evidence telling us that evolution has occurred, and is still occurring.
??? observable examples of the evolutionary process
??? fossils
??? distribution in space and time
??? homologies
Species and Speciation
??Recall the definition of a species (a topic of some debate).
Macroevolution = Speciation
Speciation is the generation of two (or possibly more) reproductively isolated new species from an ancestral species.
Speciation implies that the two new species are no longer able to produce fertile, viable offspring with each other: they are reproductively isolated.
Speciation is synonymous with macroevolution.
Speciation can be relatively quick or gradual, depending on the species and circumstances.
Microevolution
??A population can undergo genetic change with respect to other populations of the same species, but not become reproductively isolated from them. Such genetic change is known as microevolution.
There is copious documented evidence for observed instances of both macroevolution and microevolution.
Observable Examples of Evolutionary Processes
??Let us examine the various lines of evidence.
Evidence: Microevolution Observed
??There are thousands of scientifically documented cases of microevoltion. Here are a few of the more famous ones.
??1. MRSA
??? Staphylococcus aureus (S. aureus) is ubiquitous and usually harmless
??? Opportunistic infections of S. aureus can usually be treated with a penicillins, a ??-lactam antibiotic.
??? These antibiotics interfere with the activity of an enzyme used by the bacteria to construct their cell walls during cell division
??? In the early 1960s, strains of S. aureus began to show up that were not killed by methicillin (a ??-lactam relative of penicillin)
??? The ??-lactam antibiotics are so called because they all contain a ??-lactam ring (the square portion of the molecule's structure in the diagram).
??? The new S. aureus were found to be making a new enzyme, ?? lactamase, that disrupts the ?? lactam ring, rendering the antibiotic inactive.
??? These new bacteria were dubbed Methicillin-resistant Staph aureus (MRSA)
??? These are some of the nasty "flesh eating" bacteria that are becoming more and more common as overuse of antibiotics (especially in hospital settings) selects for resistance not only in S. aureus, but many other bacterial species.
??? ?? lactamases (there are many!) are believed to be derived from bacterial enzymes that originally functioned in cell wall construction.
??? Mutations of the genes encoding these original enzymes changed them into the various ?? lactamases.
??? As antibiotics evolve by human manipulation, bacterial enzymes mutate, and the beneficial mutations (such as those inactivating antibiotics) are selected.
??? An so goes the Evolutionary Arms Race.
2. Antibiotic-resistant Mycobacterium tuberculosis
??? Mycobacterium tuberculosis causes tuberculosis (TB) in humans and other primates.
??? In the middle of the 20th century, new antibiotics nearly eradicated TB
??? Late 1980's: new resurgence of TB in developing nations
??? Some strains were resistant to antibiotics to which they had been sensitive before.
??? How did this happen? "Felt need?" "Natural Selection?"
??? The answer came from an AIDS patient...??? HIV+ individual diagnosed with TB
??? treated with rifampin and isoniazid (normally effective against M. tuberculosis)
??? Infection cleared; chest radiographs normal
??? Two months later, patient readmitted with TB symptoms
??? Treated with same antibiotics, but died 10 days later
??? Culture and sensitivity test on lung discharge revealed M. tuberculosis, but these were resistant to rifampin.
Was this an example of natural selection? Let's put Darwin to the (post hoc) test.
??1. Did variation exist in the bacterial population?
YES - both sensitive and resistant strains were present in the patient)
2. Was the variation heritable?
YES- Rifampin's mode of action is to bind specifically to RNA polymerase, interfering with transcription of all genes.
Resistant M. tuberculosis had a point mutation in the RNA polymerase gene (rpoB): leucine (TCG) --> serine (TTG). This was enough to render the RNA polymerase unrecognizable to rifampin.
The mutation was heritable; all progeny of the mutant, resistant strain had the same point mutation.
3. Did differential reproduction among variable bacteria occur?
YES - M. tuberculosis with the point mutation left more offspring than those that lacked the mutation.
4. Did a non-random subset of the original population remain after selection?YES - The populations before and after rifampin administration were significantly different, with resistant bacteria replacing rifampin-sensitive individuals.
3. North American House Sparrow body mass and wing surface area ??? A tale of The American Acclimatization Society and Shakespeare...
??? Bergmann's Rule: Animals in higher latitudes/colder climates tend to have larger bodies (with a lower surface area to volume ratio) than those in lower latitudes/warmer climates. (Why should this be so?)
??? This can be true not only across species, but within a species with a wide geographic range.
??? What would you predict with respect to body size (northern hemisphere) in northern and southern populations?
??? Now consider color. Darker colors (pigments) absorbs light/heat. Lighter colors reflect light/heat.
??? What would you predict with respect to pigmentation (northern hemisphere) in northern and southern populations?
??? This was studied in House Sparrows by Johnston and Selander, who published their work in the early 1970s.
??? All House Sparrows in the U.S. are descended from a few pairs imported from central England.
??? Yet the North American populations at higher latitudes are darker and larger than those in southern populations.
4. Evolution of flower size
??? How does pollinator preference and the influence of nectar-thieving ants result in a change in the flower population (in terms of size, morphology, and fragrance)?
??? Read about this HERE!
Evidence: Macroevolution Observed
??One battle cry of those who do not wish to accept the reality of evolution is "Well, yes, we can see microevolution. But we've never observed speciation."
This is simply INCORRECT.
Evidence: What the Rocks and Fossils Tell Us
??While fossils are not the most powerful line of evidence for how life changed over time, they are vital to our understanding of how long life has been here, having the opportunity to evolve.
Paleontology and Geology were perhaps the first scientific disciplines to yield information suggesting the earth wasn't a few thousand years old. Countless mountain ranges filled with marine fossils tell us that the earth we see today was quite different long ago.
??The mountains surrounding Convict Lake in the Sierra Nevada
??contain 400-million year old marine fossils in their oldest sedimentary layers.
Still, fossils are rare. Most dead things are consumed and destroyed relatively soon after they die. Only rarely do properties of the organism and environmental conditions promote fossilization. If you're going to become a fossil, it helps to have...
??? hard body parts
??? a rapid burial
??? protection from scavengers/bacteria
??? protection from oxygen
What are Fossils?
??Fossils can be parts of an organism's body, or they can be trace fossils, left by living things long gone. The latter include??? burrows
??? tracks
??? castings
??? gastroliths (stones from inside the stomach)
??? coproliths (fossilized excrement)
??? molds (the impression left by the outside of an organism, pressed into substrate)
??? casts (the entire body of the organism, replaced by minerals)
Fossils can be unaltered (composed of actual matter from the organism):
??? encased in preserving material, such as amber
??? mummified (arid conditions)
??? frozen (for example, mammoth carcasses)
??...or they can be altered ??? permineralized - spaces in the tissue are filled by minerals over time
??? mineralized - tissues are fully replaced by minerals, but keep their shape
??All of these can be studied to track changes not only in biodiversity, but in lineages of organisms still alive today.
Relative Dating
??Early paleontologists and geologists did not have the technology to determine the absolute age of a fossil they were studying. But they were still able to determine the relative sequence of the past. The process of determining the chronological order of fossil deposition is known as relative dating.
Some common forms of sedimentary rock:
??? sandstone - compressed layers of silica-based minerals such as quartz and feldspar
??? limestone - composed of the crushed calcium carbonate shells and other parts of marine invertebrates (that's Florida!)
??? shale - compressed layers of clay
??? gypsum - composed of sulfur-containing minerals, gypsum is laid down in marine environments, and solidifies when the ocean water evaporates.
??? conglomerate
How does sedimentary rock form?
??Erosion by wind and water over millions of years will gradually wear away particles of earth and wash them into bodies of water (streams, rivers, oceans). As these particles settle to the bottom, they solidify. As more layers are laid on top of older ones, the lower layers are compressed, and eventually turn into rock. Geologists represent such formations as a stratigraphic column, which describes the vertical placement of rock layers/units in a particular location.
In Geology...
??? Older layers of sediment are covered by younger layers; the most recent layers are at the top. (Principle of Superposition)
??? If organisms evolve and change over time, then specific species found in a particular layer can be used as age markers, linking even geographically distant sediments. (Principle of Fossil Succession) Any pebbles, fossils, or other fragments embedded in sedimentary rock must be older than the rock matrix itself.
??? Intrusions that cut through sediments are younger than the sedimentary layers they cross (Principle of Cross-cutting Relationships)
??? Sedimentary rocks that have been deformed by folding, lifting or other malformation must be older than the event that changed them. (Principle of Deformation)
Using these principles, geologists can determine the relative age of fossils embedded in sedimentary rock.
To give an absolute age to a fossil, one must use radiometric techniques that we'll discuss later.
Instances of Observed Speciation
Catherine A. Callaghan
The American Biology Teacher,?? Vol. 49?? No. 1,?? Jan., 1987;?? (pp. 34-36)?? DOI: 10.2307/4448413
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Copyright ?? 2019 by the National Association of Biology Teachers Privacy???? Accessibility
Observed Instances of Speciation
by Joseph Boxhorn
Copyright ?? 1993-2004
??[Last Update: September 1, 1995]
1.0 Introduction and Acknowledgements
T his FAQ discusses several instances where speciation has been observed. It also discusses several issues related to speciation.
Other Links:
Some More Observed Speciation EventsA group of articles originally posted to the talk.origins newsgroup that provides some instances of speciation not covered by this document.
I have divided this FAQ into several sections. Part 2 discusses several definitions of what a species is. Part 3 explains the context in which observations of speciation are made. Part 4 looks at the question, "How can we tell when a speciation event has occurred?" Part 5 describes a number of observed speciation events and several experiments which (in my opinion) failed to produce speciation. Part 6 is a list of references.
The descriptions of each observation come from the primary literature. I went back to this literature for two reasons. First, many of these observations are not discussed (or not discussed in much detail) in secondary sources such as reviews, texts and popular articles. Second, it is difficult, if not impossible, to evaluate what a piece of research actually established without looking at the methods and data. Secondary sources rarely give this information in any detail. Anyway, I have included only those observations that I have been able to find the original sources for.
I consider this FAQ incomplete. One reason for this is that I am still chasing references (I still have a list of over 115 to find). More important is the fact that observations of speciation are buried in papers on a number of topics. If you know of observations that I should include, let me know and I will chase down the reference, read it and modify the file (assuming that the data are the least bit convincing). I ask that you try to give me as complete a reference as possible to aid me in finding the original source.
1.1 Acknowledgements
Back in April of 1993, Rich Fox asked a series of questions related to species and speciation events. These questions got me interested in the topic. I hope that I have, at least, provided grist for the mill that will grind out an answer to Rich's questions. In any case, Rich deserves the credit (or blame :-)) for inspiring me to write this. My starting point was the references contained in the old speciation FAQ. I wish to thank the authors of this, Chris Stassen, James Meritt, Anneliese Lilje and L. Drew Davis. Tom Scharle and Simon Clippingdale sent a couple of references my way. Finally, John Edstrom sent me considerable information on symbiosis in Amoeba. While I have not had a chance to get all the references that he has sent me, he has given me a great deal to think about over the role of symbiosis in speciation. Many thanks to all.
2.0 Species Definitions
A discussion of speciation requires a definition of what constitutes a species. This is a topic of considerable debate within the biological community. Three recent reviews in the Journal of Phycology give some idea of the scope of the debate (Castenholz 1992, Manhart and McCourt 1992, Wood and Leatham 1992). There are a variety of different species concept currently in use by biologists. These include folk, biological, morphological, genetic, paleontological, evolutionary, phylogenetic and biosystematic definitions. In the interest of brevity, I'll only discuss four of these -- folk, biological, morphological and phylogenetic. A good review of species definitions is given in Stuessy 1990.
2.1 The Folk Concept of Species
Naturalists around the world have found that the individual plants and animals they see can be mentally grouped into a number of taxa, in which the individuals are basically alike. In societies that are close to nature, each taxon is given a name. These sorts of folk taxonomies have two features in common. One aspect is the idea of reproductive compatability and continuity within a species. Dogs beget dogs, they never beget cats! This has a firm grounding in folk knowledge. The second notion is that there is a discontinuity of variation between species. In other words, you can tell species apart by looking at them (Cronquist 1988).
2.2 The Biological Species Concept
Over the last few decades the theoretically preeminent species definition has been the biological species concept (BSC). This concept defines a species as a reproductive community.
2.2.1 History of the Biological Species Concept
The BSC has undergone a number of changes over the years. The earliest precursor that I could find was in Du Rietz 1930. Du Rietz defined a species as
"... the smallest natural populations permanently separated from each other by a distinct discontinuity in the series of biotypes."
Barriers to interbreeding are implicit in this definition and explicit in Du Rietz's dicussion of it.
A few years later, Dobzhansky defined a species as
"... that stage of evolutionary progress at which the once actually or potentially interbreeding array of forms becomes segregated into two or more separate arrays which are physiologically incapable of interbreeding." (Dobzhansky 1937)
It is important to note that this is a highly restrictive definition of species. It emphasizes experimental approaches and ignores what goes on in nature. By the publication of the third edition of the book this appeared in, Dobzhansky (1951) had relaxed this definition to the point that is substantially agreed with Mayr's.
The definition of a species that is accepted as the BSC was promulgated by Mayr (1942). He defined species as
"... groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups."
Note that the emphasis in this definition is on what happens in nature. Mayr later amended this definition to include an ecological component. In this form of the definition a species is
"... a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature."
The BSC is most strongly accepted among vertebrate zoologists and entomologists. Two facts account for this. First, these are the groups that the authors of the BSC worked with :-). (Note: Mayr is an ornithologist and Dobzhansky worked extensively with Drosophila). More importantly, obligate sexuality is the predominant form of reproduction in these groups. It is not coincidental that the BSC is less widely accepted among botanists. Terrestrial plants exhibit much greater diversity in their "mode of reproduction" than do vertebrates and insects.
2.2.2 Criticisms of the Biological Species Concept
There has been considerable criticism of the theoretical validity and practical utility of the BSC. (Cracraft 1989, Donoghue 1985, Levin 1979, Mishler and Donoghue 1985, Sokal and Crovello 1970).
The application of the BSC to a number of groups, including land plants, is problematical because of interspecific hybridization between clearly delimited species (McCourt and Hoshaw 1990, Mishler 1985).
There is an abundance of asexual populations that this definition just doesn't apply to (Budd and Mishler 1990). Examples of taxa which are obligately asexual include bdelloid rotifers, euglenoid flagellates, some members of the Oocystaceae (coccoid green algae), chloromonad flagellates and some araphid pennate diatoms. Asexual forms of normally sexual organisms are known. Obligately asexual populations of Daphnia are found in some arctic lakes. The BSD can be of no help in delimiting species in these groups. A similar situation is found in the prokaryotes. Though genes can be exchanged among bacteria by a number of mechanisms, sexuality, as defined in eukaryotes, in unknown in the prokaryotes. One popular microbiology text doesn't even mention the BSC (Brock and Madigan 1988).
The applicability of the BSC is also questionable in those land plants that primarily self-pollinate (Cronquist 1988).
A more serious criticism is that the BSC is inapplicable in practice. This charge asserts that, in most cases, the BSC cannot be practically applied to delimit species. The BSC suggests breeding experiments as the test of species membership. But this is a test that is rarely made. The number of crosses needed to delimit membership in a species can be astronomical. The following example will illustrate the problem.
Here in Wisconsin we have about 16,000 lakes and ponds. A common (and tasty ;-)) inhabitant of many of these bodies of water is the bluegill sunfish. Let's ask a question -- do all these bluegill populations constitute one species or several morphologically similar species? Assume that only 1,000 of these lakes and ponds contain bluegills. Assuming that each lake constitutes a population, an investigator would have to perform 499,500 separate crosses to determine whether the populations could interbreed. But to do this right we should really do reciprocal crosses (i.e. cross a male from population A with a female from population B and a male from population B with a female from population A). This brings the total crosses we need to make up to 999,000. But don't we also need to make replicates? Having three replicates brings the total to 2,997,000 crosses. In addition, you just can't put a pair of bluegills into a bucket and expect them to mate. In nature, male bluegills excavate and defend nests in large mating colonies. After the nests are excavated the females come in to the colony to spawn. Here the females choose among potential mates. This means that we would need to simulate a colony in our test. Assume that 20 fish would be sufficient for a single test. We find that we would need about 60,000,000 fish to test whether all these populations are members of the same species! (We would also need a large number of large aquaria to run these crosses in). But bluegills are not restricted to Wisconsin...
I could go on, but I think the point is now obvious. The fact of the matter is that the time, effort and money needed to delimit species using the BSC is, to say the least, prohibitive.
Another reason why using the BSC to delimit species is impractical is that breeding experiments can often be inconclusive. Interbreeding in nature can be heavily influenced by variable and unstable environmental factors. (Any angler who has waited for the bluegills to get on to the beds can confirm this one). If we can't duplicate natural conditions of breeding, a failure to breed doesn't mean that the critters can't (or don't) interbreed in the wild. The difficulties that were encountered in breeding pandas in captivity illustrate this. In addition, experimentally showing that A doesn't interbreed with B doesn't preclude both interbreeding with C. This gets even more complicated in groups that don't have nice, straightforward sexes. An example of this occurs in a number of protozoan species. These critters have numerous mating types. There can be very complicated compatability of mating types. Finally, breeding experiments can be inconclusive because actual interbreeding and gene flow among phenetically similar, genetically compatible local populations is often more restricted than the BSC would suggest (Cronquist 1988).
In practice, even strong adherents of the BSC use phenetic similarities and discontinuities for delimiting species. If the organisms are phenotypically similar, they are considered conspecific until a reproductive barrier is demonstrated.
Another criticism of the BSC comes from the cladistic school of taxonomy (e.g. Donoghue 1985). The cladists argue that sexual compatibility is a primitive trait. Organisms that are no longer closely related may have retained the ability for genetic recombination with each other through sex. This is not a derived characteristic. Because of this it is invalid for defining monophyletic taxa.
A final problem with the BSC is that groups that do not occur together in time cannot be evaluated. We simply cannot know whether two such groups would interbreed freely if they came together under natural conditions. This makes it impossible to delimit the boundaries of extinct groups using the BSC. One question will illustrate the problem. Do Homo erectus and Homo sapiens represent the same or different species? This question is unresolvable using the biological definition.
Several alternatives to the biological species concept have been suggested. I will discuss two.
2.3 The Phenetic (or Morphological) Species Concept
Cronquist (1988) proposed an alternative to the BSC that he called a "renewed practical species definition". He defines species as
"... the smallest groups that are consistently and persistently distinct and distinguishable by ordinary means."
Three comments must be made about this definition. First, "ordinary means" includes any techniques that are widely available, cheap and relatively easy to apply. These means will differ among different groups of organisms. For example, to a botanist working with angiosperms ordinary means might mean a hand lens; to an entomologist working with beetles it might mean a dissecting microscope; to a phycologist working with diatoms it might mean a scanning electron microscope. What means are ordinary are determined by what is needed to examine the organisms in question.
Second, the requirement that species be persistently distinct implies a certain degree of reproductive continuity. This is because phenetic discontinuity between groups cannot persist in the absence of a barrier to interbreeding.
Third, this definition places a heavy, though not exclusive, emphasis on morphological characters. It also recognizes phenetic characters such as chromosome number, chromosome morphology, cell ultrastructure, secondary metabolites, habitats and other features.
2.4 Phylogenetic Species Concepts
There are several phylogenetic species definitions. All of them assert that classifications should reflect the best supported hypotheses of the phylogeny of the organisms. Baum (1992) describes two types of phylogenetic species concepts.
1.A species is the smallest cluster of organisms that possesses at least one diagnostic character. This character may be morphological, biochemical or molecular and must be fixed in reproductively cohesive units. It is important to realize that this reproductive continuity is not used in the same way as in the BSC. Phylogenetic species may be reproductive communities. Reproductively compatible individuals need not have the diagnostic character of a species. In this case, the individuals need not be conspecific.
2.A species must be monophyletic and share one or more derived character. There are two meanings to monophyletic (de Queiroz and Donoghue 1988, Nelson 1989). The first defines a monophyletic group as all the descendants of a common ancestor and the ancestor. The second defines a monophyletic group as a group of organisms that are more closely related to each other than to any other organisms. These distinctions are discussed in Baum 1992 and de Queiroz and Donoghue 1990.
A recently offered hypothesis suggests that phylogenetic species concepts and the biological species concept may be highly, if not completely, incompatible. "Parallel speciation " has been defined as the repeated independent evolution of the same reproductive isolating mechanism (Schluter and Nagel 1995). An example of this may occur when a species colonizes several new areas which are isolated from, but environmentally similar to, each other. Similar selective pressures in these environments result in parallel evolution among the traits that confer reproductive isolation. There is some experimental evidence that this might occur (Kilias, et al. 1980; Dodd 1989). The implication of this is that biological species (as defined by the BSC) may often be polyphyletic. If this occurs in nature, it could undermine the usefulness of phylogenetic species concepts.
2.5 Why This is Included
What is all of this doing in a discussion of observed instances of speciation? What a biologist will consider as a speciation event is, in part, dependent on which species definition that biologist accepts. The biological species concept has been very successful as a theoretical model for explaining species differences among vertebrates and some groups of arthropods. This can lead us to glibly assert its universal applicability, despite its irrelevance to many groups. When we examine putative speciation events, we need to ask the question, which species definition is the most reasonable for this group of organisms? In many cases it will be the biological definition. In many other cases some other definition will be more appropriate.
3.0 The Context of Reports of Observed Speciations
The literature on observed speciations events is not well organized. I found only a few papers that had an observation of a speciation event as the author's main point (e.g. Weinberg, et al. 1992). In addition, I found only one review that was specifically on this topic (Callaghan 1987). This review cited only four examples of speciation events. Why is there such a seeming lack of interest in reporting observations of speciation events?
In my humble opinion, four things account for this lack of interest. First, it appears that the biological community considers this a settled question. Many researchers feel that there are already ample reports in the literature. Few of these folks have actually looked closely. To test this idea, I asked about two dozen graduate students and faculty members in the department where I'm a student whether there were examples where speciation had been observed in the literature. Everyone said that they were sure that there were. Next I asked them for citings or descriptions. Only eight of the people I talked to could give an example, only three could give more than one. But everyone was sure that there were papers in the literature.
Second, most biologists accept the idea that speciation takes a long time (relative to human life spans). Because of this we would not expect to see many speciation events actually occur. The literature has many more examples where a speciation event has been inferred from evidence than it has examples where the event is seen. This is what we would expect if speciation takes a long time.
Third, the literature contains many instances where a speciation event has been inferred. The number and quality of these cases may be evidence enough to convince most workers that speciation does occur.
Finally, most of the current interest in speciation concerns theoretical issues. Most biologists are convinced that speciation occurs. What they want to know is how it occurs. One recent book on speciation (Otte and Endler 1989) has few example of observed speciation, but a lot of discussion of theory and mechanisms.
Most of the reports, especially the recent reports, can be found in papers that describe experimental tests of hypotheses related to speciation. Usually these experiments focus on questions related to mechanisms of speciation. Examples of these questions include:
???Does speciation precede or follow adaptation to local ecological conditions?
???Is speciation a by-product of genetic divergence among populations or does it occur directly by natural selection through lower fitness of hybrids?
???How quickly does speciation occur?
???What roles do bottlenecks and genetic drift play in speciation?
???Can speciation occur sympatrically (i.e. can two or more lineages diverge while they are intermingled in the same place) or must the populations be separated in space or time?
???What roles do pleiotropy and genetic hitchhiking play in speciation?
It is important to note that a common theme running through these questions is that they all attempt to address the issue of how speciation occurs.
4.0 Telling Whether a Speciation Event Has Occurred
What evidence is necessary to show that a change produced in a population of organisms constitutes a speciation event? The answer to this question will depend on which species definition applies to the organisms involved.
4.1 Cases Where the Biological Species Concept Applies
One advantage of the BSC is that it provides a reasonably unambiguous test that can be applied to possible speciation events. Recall that under the BSC species are defined as being reproductively isolated from other species. Demonstrating that a population is reproductively isolated (in a nontrivial way) from populations that it was formerly able to interbreed with shows that speciation has occurred. In practice, it is also necessary to show that at least one isolating mechanism with a hereditary basis is present. After all, just because a pair of critters don't breed during an experiment doesn't mean they can't breed or even that they won't breed. Debates about whether a speciation event has occurred often turn on whether isolating mechanisms have been produced.
4.1.1 Isolating Mechanisms
Mechanisms which produce reproductive isolation fall into two broad categories -- premating mechanisms and postmating mechanisms.
Premating isolating mechanisms operate to keep species separate before mating occurs. Often they act to prevent mating altogether. Examples of premating mechanisms include ecological, temporal, behavioral and mechanical mechanisms.
Ecological isolation occurs when species occupy or breed in different habitats. It is important to be careful when claiming ecological isolation. For example, I have a population of Dinobryon cylindricum (a colonial algal flagellate) growing in a culture tube in an environmental chamber. It's been there for three years (which is a lot of time in flagellate years! :-)). Even though there is no possibility that they will mate with the D. cylindricum in Lake Michigan, it would be silly to assert that they therefore constitute a separate species. Physical isolation alone does not constitute an isolating mechanism with an hereditary basis.
Temporal isolation occurs when species breed at different times. This may be different times of the year or different times of day.
Behavioral isolating mechanisms rely on organisms making a choice of whether to mate and a choice of who to mate with. Differences in courtship behavior, for instance, may be sufficient to prevent mating from occurring. A behavioral isolating mechanism should result in some sort of positive assortative mating. Simply put, positive assortative mating occurs when organisms that differ in some way tend to mate with organism that are like themselves. For example, if blonds mate exclusively with blonds, brunettes mate exclusively with brunettes, redheads mate exclusively with redheads (and those of us without much hair don't get to mate :-() the human population would exhibit a high degree of positive assortative mating. In most examples in the literature when positive assortative mating is seen it is not this strong. Positive assortative mating is especially important in discussions of sympatric speciation.
Mechanical isolating mechanisms occur when morphological or physiological differences prevent normal mating.
Postmating isolating mechanisms prevent hybrid offspring from developing or breeding when mating does occur. There are also several examples of postmating mechanisms.
Mechanical postmating isolating mechanisms occur in those cases where mating is possible, but the gametes are unable to reach each other or to fuse. Mortality acts as an isolating mechanism when the hybrid dies prior to maturity. Sterility of hybrids can act as an isolating mechanism. Finally a reduction in the fitness of the hybrid offspring can isolate two populations. This happens when the F1 hybrid is fertile but the F2 hybrid has lower fitness than either of the parental species.
4.2 Cases Where the Biological Species Concept Does Not Apply
There is no unambiguous criterion for determining that a speciation event has occurred in those cases where the BSC does not apply. This is especially true for obligately asexual organisms. Usually phenetic (e.g. phenotypic and genetic) differences between populations are used to justify a claim of speciation. A few caveats are germane to this. It is not obvious how much change is necessary to claim that a population has speciated. In my humble opinion, the difference between the "new species" and its "ancestor" should be at least as great as the differences among recognized species in the group (i.e. genus, family) involved. The investigator should show that the change is persistent. Finally, many organisms have life cycles/life histories that involve alternative morphologies and/or an ability to adjust their phenotypes in response to short term changes in ecological conditions. The investigator should be sure to rule these things out before claiming that a phenetic change constitutes a speciation event.
5.0 Observed Instances of Speciation
The following are several examples of observations of speciation.
5.1 Speciations Involving Polyploidy, Hybridization or Hybridization Followed by Polyploidization.
5.1.1 Plants
(See also the discussion in de Wet 1971).
5.1.1.1 Evening Primrose (Oenothera gigas)
While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species O. gigas.
5.1.1.2 Kew Primrose (Primula kewensis)
Digby (1912) crossed the primrose species Primula verticillata and P. floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named P. kewensis. Newton and Pellew (1929) note that spontaneous hybrids of P. verticillata and P. floribunda set tetraploid seed on at least three occasions. These happened in 1905, 1923 and 1926.
5.1.1.3 Tragopogon
Owenby (1950) demonstrated that two species in this genus were produced by polyploidization from hybrids. He showed that Tragopogon miscellus found in a colony in Moscow, Idaho was produced by hybridization of T. dubius and T. pratensis. He also showed that T. mirus found in a colony near Pullman, Washington was produced by hybridization of T. dubius and T. porrifolius. Evidence from chloroplast DNA suggests that T. mirus has originated independently by hybridization in eastern Washington and western Idaho at least three times (Soltis and Soltis 1989). The same study also shows multiple origins for T. micellus.
5.1.1.4 Raphanobrassica
The Russian cytologist Karpchenko (1927, 1928) crossed the radish, Raphanus sativus, with the cabbage, Brassica oleracea. Despite the fact that the plants were in different genera, he got a sterile hybrid. Some unreduced gametes were formed in the hybrids. This allowed for the production of seed. Plants grown from the seeds were interfertile with each other. They were not interfertile with either parental species. Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage.
5.1.1.5 Hemp Nettle (Galeopsis tetrahit)
A species of hemp nettle, Galeopsis tetrahit, was hypothesized to be the result of a natural hybridization of two other species, G. pubescens and G. speciosa (Muntzing 1932). The two species were crossed. The hybrids matched G. tetrahit in both visible features and chromosome morphology.
5.1.1.6 Madia citrigracilis
Along similar lines, Clausen et al. (1945) hypothesized that Madia citrigracilis was a hexaploid hybrid of M. gracilis and M. citriodora As evidence they noted that the species have gametic chromosome numbers of n = 24, 16 and 8 respectively. Crossing M. gracilis and M. citriodora resulted in a highly sterile triploid with n = 24. The chromosomes formed almost no bivalents during meiosis. Artificially doubling the chromosome number using colchecine produced a hexaploid hybrid which closely resembled M. citrigracilis and was fertile.
5.1.1.7 Brassica
Frandsen (1943, 1947) was able to do this same sort of recreation of species in the genus Brassica (cabbage, etc.). His experiments showed that B. carinata (n = 17) may be recreated by hybridizing B. nigra (n = 8) and B. oleracea, B. juncea (n = 18) may be recreated by hybridizing B. nigra and B. campestris (n = 10), and B. napus (n = 19) may be recreated by hybridizing B. oleracea and B. campestris.
5.1.1.8 Maidenhair Fern (Adiantum pedatum)
Rabe and Haufler (1992) found a naturally occurring diploid sporophyte of maidenhair fern which produced unreduced (2N) spores. These spores resulted from a failure of the paired chromosomes to dissociate during the first division of meiosis. The spores germinated normally and grew into diploid gametophytes. These did not appear to produce antheridia. Nonetheless, a subsequent generation of tetraploid sporophytes was produced. When grown in the lab, the tetraploid sporophytes appear to be less vigorous than the normal diploid sporophytes. The 4N individuals were found near Baldwin City, Kansas.
5.1.1.9 Woodsia Fern (Woodsia abbeae)
Woodsia abbeae was described as a hybrid of W. cathcariana and W. ilvensis (Butters 1941). Plants of this hybrid normally produce abortive sporangia containing inviable spores. In 1944 Butters found a W. abbeae plant near Grand Portage, Minn. that had one fertile frond (Butters and Tryon 1948). The apical portion of this frond had fertile sporangia. Spores from this frond germinated and grew into prothallia. About six months after germination sporophytes were produced. They survived for about one year. Based on cytological evidence, Butters and Tryon concluded that the frond that produced the viable spores had gone tetraploid. They made no statement as to whether the sporophytes grown produced viable spores.
5.1.2 Animals
Speciation through hybridization and/or polyploidy has long been considered much less important in animals than in plants [[[refs.]]]. A number of reviews suggest that this view may be mistaken. (Lokki and Saura 1980; Bullini and Nascetti 1990; Vrijenhoek 1994). Bullini and Nasceti (1990) review chromosomal and genetic evidence that suggest that speciation through hybridization may occur in a number of insect species, including walking sticks, grasshoppers, blackflies and cucurlionid beetles. Lokki and Saura (1980) discuss the role of polyploidy in insect evolution. Vrijenhoek (1994) reviews the literature on parthenogenesis and hybridogenesis in fish. I will tackle this topic in greater depth in the next version of this document.
5.2 Speciations in Plant Species not Involving Hybridization or Polyploidy
5.2.1 Stephanomeira malheurensis
Gottlieb (1973) documented the speciation of Stephanomeira malheurensis. He found a single small population (< 250 plants) among a much larger population (> 25,000 plants) of S. exigua in Harney Co., Oregon. Both species are diploid and have the same number of chromosomes (N = 8). S. exigua is an obligate outcrosser exhibiting sporophytic self-incompatibility. S. malheurensis exhibits no self-incompatibility and self-pollinates. Though the two species look very similar, Gottlieb was able to document morphological differences in five characters plus chromosomal differences. F1 hybrids between the species produces only 50% of the seeds and 24% of the pollen that conspecific crosses produced. F2 hybrids showed various developmental abnormalities.
5.2.2 Maize (Zea mays)
Pasterniani (1969) produced almost complete reproductive isolation between two varieties of maize. The varieties were distinguishable by seed color, white versus yellow. Other genetic markers allowed him to identify hybrids. The two varieties were planted in a common field. Any plant's nearest neighbors were always plants of the other strain. Selection was applied against hybridization by using only those ears of corn that showed a low degree of hybridization as the source of the next years seed. Only parental type kernels from these ears were planted. The strength of selection was increased each year. In the first year, only ears with less than 30% intercrossed seed were used. In the fifth year, only ears with less than 1% intercrossed seed were used. After five years the average percentage of intercrossed matings dropped from 35.8% to 4.9% in the white strain and from 46.7% to 3.4% in the yellow strain.
5.2.3 Speciation as a Result of Selection for Tolerance to a Toxin: Yellow Monkey Flower (Mimulus guttatus)
At reasonably low concentrations, copper is toxic to many plant species. Several plants have been seen to develop a tolerance to this metal (Macnair 1981). Macnair and Christie (1983) used this to examine the genetic basis of a postmating isolating mechanism in yellow monkey flower. When they crossed plants from the copper tolerant "Copperopolis" population with plants from the nontolerant "Cerig" population, they found that many of the hybrids were inviable. During early growth, just after the four leaf stage, the leaves of many of the hybrids turned yellow and became necrotic. Death followed this. This was seen only in hybrids between the two populations. Through mapping studies, the authors were able to show that the copper tolerance gene and the gene responsible for hybrid inviability were either the same gene or were very tightly linked. These results suggest that reproductive isolation may require changes in only a small number of genes.
5.3 The Fruit Fly Literature
5.3.1 Drosophila paulistorum
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
5.3.2 Disruptive Selection on Drosophila melanogaster
Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs). In each generation, eight flies with high numbers of chaetae were allowed to interbreed and eight flies with low numbers of chaetae were allowed to interbreed. Periodically they performed mate choice experiments on the two lines. They found that they had produced a high degree of positive assortative mating between the two groups. In the decade or so following this, eighteen labs attempted unsuccessfully to reproduce these results. References are given in Thoday and Gibson 1970.
5.3.3 Selection on Courtship Behavior in Drosophila melanogaster
Crossley (1974) was able to produce changes in mating behavior in two mutant strains of D. melanogaster. Four treatments were used. In each treatment, 55 virgin males and 55 virgin females of both ebony body mutant flies and vestigial wing mutant flies (220 flies total) were put into a jar and allowed to mate for 20 hours. The females were collected and each was put into a separate vial. The phenotypes of the offspring were recorded. Wild type offspring were hybrids between the mutants. In two of the four treatments, mating was carried out in the light. In one of these treatments all hybrid offspring were destroyed. This was repeated for 40 generations. Mating was carried out in the dark in the other two treatments. Again, in one of these all hybrids were destroyed. This was repeated for 49 generations. Crossley ran mate choice tests and observed mating behavior. Positive assortative mating was found in the treatment which had mated in the light and had been subject to strong selection against hybridization. The basis of this was changes in the courtship behaviors of both sexes. Similar experiments, without observation of mating behavior, were performed by Knight, et al. (1956).
5.3.4 Sexual Isolation as a Byproduct of Adaptation to Environmental Conditions in Drosophila melanogaster
Kilias, et al. (1980) exposed D. melanogaster populations to different temperature and humidity regimes for several years. They performed mating tests to check for reproductive isolation. They found some sterility in crosses among populations raised under different conditions. They also showed some positive assortative mating. These things were not observed in populations which were separated but raised under the same conditions. They concluded that sexual isolation was produced as a byproduct of selection.
5.3.5 Sympatric Speciation in Drosophila melanogaster
In a series of papers (Rice 1985, Rice and Salt 1988 and Rice and Salt 1990) Rice and Salt presented experimental evidence for the possibility of sympatric speciation. They started from the premise that whenever organisms sort themselves into the environment first and then mate locally, individuals with the same habitat preferences will necessarily mate assortatively. They established a stock population of D. melanogaster with flies collected in an orchard near Davis, California. Pupae from the culture were placed into a habitat maze. Newly emerged flies had to negotiate the maze to find food. The maze simulated several environmental gradients simultaneously. The flies had to make three choices of which way to go. The first was between light and dark (phototaxis). The second was between up and down (geotaxis). The last was between the scent of acetaldehyde and the scent of ethanol (chemotaxis). This divided the flies among eight habitats. The flies were further divided by the time of day of emergence. In total the flies were divided among 24 spatio-temporal habitats.
They next cultured two strains of flies that had chosen opposite habitats. One strain emerged early, flew upward and was attracted to dark and acetaldehyde. The other emerged late, flew downward and was attracted to light and ethanol. Pupae from these two strains were placed together in the maze. They were allowed to mate at the food site and were collected. Eye color differences between the strains allowed Rice and Salt to distinguish between the two strains. A selective penalty was imposed on flies that switched habitats. Females that switched habitats were destroyed. None of their gametes passed into the next generation. Males that switched habitats received no penalty. After 25 generations of this mating tests showed reproductive isolation between the two strains. Habitat specialization was also produced.
They next repeated the experiment without the penalty against habitat switching. The result was the same -- reproductive isolation was produced. They argued that a switching penalty is not necessary to produce reproductive isolation. Their results, they stated, show the possibility of sympatric speciation.
5.3.6 Isolation Produced as an Incidental Effect of Selection on several Drosophila species
In a series of experiments, del Solar (1966) derived positively and negatively geotactic and phototactic strains of D. pseudoobscura from the same population by running the flies through mazes. Flies from different strains were then introduced into mating chambers (10 males and 10 females from each strain). Matings were recorded. Statistically significant positive assortative mating was found.
In a separate series of experiments Dodd (1989) raised eight populations derived from a single population of D. Pseudoobscura on stressful media. Four populations were raised on a starch based medium, the other four were raised on a maltose based medium. The fly populations in both treatments took several months to get established, implying that they were under strong selection. Dodd found some evidence of genetic divergence between flies in the two treatments. He performed mate choice tests among experimental populations. He found statistically significant assortative mating between populations raised on different media, but no assortative mating among populations raised within the same medium regime. He argued that since there was no direct selection for reproductive isolation, the behavioral isolation results from a pleiotropic by-product to adaptation to the two media. Schluter and Nagel (1995) have argued that these results provide experimental support for the hypothesis of parallel speciation.
Less dramatic results were obtained by growing D. willistoni on media of different pH levels (de Oliveira and Cordeiro 1980). Mate choice tests after 26, 32, 52 and 69 generations of growth showed statistically significant assortative mating between some populations grown in different pH treatments. This ethological isolation did not always persist over time. They also found that some crosses made after 106 and 122 generations showed significant hybrid inferiority, but only when grown in acid medium.
5.3.7 Selection for Reinforcement in Drosophila melanogaster
Some proposed models of speciation rely on a process called reinforcement to complete the speciation process. Reinforcement occurs when to partially isolated allopatric populations come into contact. Lower relative fitness of hybrids between the two populations results in increased selection for isolating mechanisms. I should note that a recent review (Rice and Hostert 1993) argues that there is little experimental evidence to support reinforcement models. Two experiments in which the authors argue that their results provide support are discussed below.
Ehrman (1971) established strains of wild-type and mutant (black body) D. melanogaster. These flies were derived from compound autosome strains such that heterotypic matings would produce no progeny. The two strains were reared together in common fly cages. After two years, the isolation index generated from mate choice experiments had increased from 0.04 to 0.43, indicating the appearance of considerable assortative mating. After four years this index had risen to 0.64 (Ehrman 1973).
Along the same lines, Koopman (1950) was able to increase the degree of reproductive isolation between two partially isolated species, D. pseudoobscura and D. persimilis.
5.3.8 Tests of the Founder-flush Speciation Hypothesis Using Drosophila
The founder-flush (a.k.a. flush-crash) hypothesis posits that genetic drift and founder effects play a major role in speciation (Powell 1978). During a founder-flush cycle a new habitat is colonized by a small number of individuals (e.g. one inseminated female). The population rapidly expands (the flush phase). This is followed by the population crashing. During this crash period the population experiences strong genetic drift. The population undergoes another rapid expansion followed by another crash. This cycle repeats several times. Reproductive isolation is produced as a byproduct of genetic drift.
Dodd and Powell (1985) tested this hypothesis using D. pseudoobscura. A large, heterogeneous population was allowed to grow rapidly in a very large population cage. Twelve experimental populations were derived from this population from single pair matings. These populations were allowed to flush. Fourteen months later, mating tests were performed among the twelve populations. No postmating isolation was seen. One cross showed strong behavioral isolation. The populations underwent three more flush-crash cycles. Forty-four months after the start of the experiment (and fifteen months after the last flush) the populations were again tested. Once again, no postmating isolation was seen. Three populations showed behavioral isolation in the form of positive assortative mating. Later tests between 1980 and 1984 showed that the isolation persisted, though it was weaker in some cases.
Galina, et al. (1993) performed similar experiments with D. pseudoobscura. Mating tests between populations that underwent flush-crash cycles and their ancestral populations showed 8 cases of positive assortative mating out of 118 crosses. They also showed 5 cases of negative assortative mating (i.e. the flies preferred to mate with flies of the other strain). Tests among the founder-flush populations showed 36 cases of positive assortative mating out of 370 crosses. These tests also found 4 cases of negative assortative mating. Most of these mating preferences did not persist over time. Galina, et al. concluded that the founder-flush protocol yields reproductive isolation only as a rare and erratic event.
Ahearn (1980) applied the founder-flush protocol to D. silvestris. Flies from a line of this species underwent several flush-crash cycles. They were tested in mate choice experiments against flies from a continuously large population. Female flies from both strains preferred to mate with males from the large population. Females from the large population would not mate with males from the founder flush population. An asymmetric reproductive isolation was produced.
In a three year experiment, Ringo, et al. (1985) compared the effects of a founder-flush protocol to the effects of selection on various traits. A large population of D. simulans was created from flies from 69 wild caught stocks from several locations. Founder-flush lines and selection lines were derived from this population. The founder-flush lines went through six flush-crash cycles. The selection lines experienced equal intensities of selection for various traits. Mating test were performed between strains within a treatment and between treatment strains and the source population. Crosses were also checked for postmating isolation. In the selection lines, 10 out of 216 crosses showed positive assortative mating (2 crosses showed negative assortative mating). They also found that 25 out of 216 crosses showed postmating isolation. Of these, 9 cases involved crosses with the source population. In the founder-flush lines 12 out of 216 crosses showed positive assortative mating (3 crosses showed negative assortative mating). Postmating isolation was found in 15 out of 216 crosses, 11 involving the source population. They concluded that only weak isolation was found and that there was little difference between the effects of natural selection and the effects of genetic drift.
A final test of the founder-flush hypothesis will be described with the housefly cases below.
5.4 Housefly Speciation Experiments
5.4.1 A Test of the Founder-flush Hypothesis Using Houseflies
Meffert and Bryant (1991) used houseflies to test whether bottlenecks in populations can cause permanent alterations in courtship behavior that lead to premating isolation. They collected over 100 flies of each sex from a landfill near Alvin, Texas. These were used to initiate an ancestral population. From this ancestral population they established six lines. Two of these lines were started with one pair of flies, two lines were started with four pairs of flies and two lines were started with sixteen pairs of flies. These populations were flushed to about 2,000 flies each. They then went through five bottlenecks followed by flushes. This took 35 generations. Mate choice tests were performed. One case of positive assortative mating was found. One case of negative assortative mating was also found.
5.4.2 Selection for Geotaxis with and without Gene Flow
Soans, et al. (1974) used houseflies to test Pimentel's model of speciation. This model posits that speciation requires two steps. The first is the formation of races in subpopulations. This is followed by the establishment of reproductive isolation. Houseflies were subjected to intense divergent selection on the basis of positive and negative geotaxis. In some treatments no gene flow was allowed, while in others there was 30% gene flow. Selection was imposed by placing 1000 flies into the center of a 108 cm vertical tube. The first 50 flies that reached the top and the first 50 flies that reached the bottom were used to found positively and negatively geotactic populations. Four populations were established:
Population A + geotaxis, no gene flow
Population B - geotaxis, no gene flow
Population C + geotaxis, 30% gene flow
Population D - geotaxis, 30% gene flow
Selection was repeated within these populations each generations. After 38 generations the time to collect 50 flies had dropped from 6 hours to 2 hours in Pop A, from 4 hours to 4 minutes in Pop B, from 6 hours to 2 hours in Pop C and from 4 hours to 45 minutes in Pop D. Mate choice tests were performed. Positive assortative mating was found in all crosses. They concluded that reproductive isolation occurred under both allopatric and sympatric conditions when very strong selection was present.
Hurd and Eisenberg (1975) performed a similar experiment on houseflies using 50% gene flow and got the same results.
5.5 Speciation Through Host Race Differentiation
Recently there has been a lot of interest in whether the differentiation of an herbivorous or parasitic species into races living on different hosts can lead to sympatric speciation. It has been argued that in animals that mate on (or in) their preferred hosts, positive assortative mating is an inevitable byproduct of habitat selection (Rice 1985; Barton, et al. 1988). This would suggest that differentiated host races may represent incipient species.
5.5.1 Apple Maggot Fly (Rhagoletis pomonella)
Rhagoletis pomonella is a fly that is native to North America. Its normal host is the hawthorn tree. Sometime during the nineteenth century it began to infest apple trees. Since then it has begun to infest cherries, roses, pears and possibly other members of the rosaceae. Quite a bit of work has been done on the differences between flies infesting hawthorn and flies infesting apple. There appear to be differences in host preferences among populations. Offspring of females collected from on of these two hosts are more likely to select that host for oviposition (Prokopy et al. 1988). Genetic differences between flies on these two hosts have been found at 6 out of 13 allozyme loci (Feder et al. 1988, see also McPheron et al. 1988). Laboratory studies have shown an asynchrony in emergence time of adults between these two host races (Smith 1988). Flies from apple trees take about 40 days to mature, whereas flies from hawthorn trees take 54-60 days to mature. This makes sense when we consider that hawthorn fruit tends to mature later in the season that apples. Hybridization studies show that host preferences are inherited, but give no evidence of barriers to mating. This is a very exciting case. It may represent the early stages of a sympatric speciation event (considering the dispersal of R. pomonella to other plants it may even represent the beginning of an adaptive radiation). It is important to note that some of the leading researchers on this question are urging caution in interpreting it. Feder and Bush (1989) stated:
"Hawthorn and apple "host races" of R. pomonella may therefore represent incipient species. However, it remains to be seen whether host-associated traits can evolve into effective enough barriers to gene flow to result eventually in the complete reproductive isolation of R. pomonella populations."
5.5.2 Gall Former Fly (Eurosta solidaginis)
Eurosta solidaginis is a gall forming fly that is associated with goldenrod plants. It has two hosts: over most of its range it lays its eggs in Solidago altissima, but in some areas it uses S. gigantea as its host. Recent electrophoretic work has shown that the genetic distances among flies from different sympatric hosts species are greater than the distances among flies on the same host in different geographic areas (Waring et al. 1990). This same study also found reduced variability in flies on S. gigantea. This suggests that some E. solidaginis have recently shifted hosts to this species. A recent study has compared reproductive behavior of the flies associated with the two hosts (Craig et al. 1993). They found that flies associated with S. gigantea emerge earlier in the season than flies associated with S. altissima. In host choice experiments, each fly strain ovipunctured its own host much more frequently than the other host. Craig et al. (1993) also performed several mating experiments. When no host was present and females mated with males from either strain, if males from only one strain were present. When males of both strains were present, statistically significant positive assortative mating was seen. In the presence of a host, assortative mating was also seen. When both hosts and flies from both populations were present, females waited on the buds of the host that they are normally associated with. The males fly to the host to mate. Like the Rhagoletis case above, this may represent the beginning of a sympatric speciation.
5.6 Flour Beetles (Tribolium castaneum)
Halliburton and Gall (1981) established a population of flour beetles collected in Davis, California. In each generation they selected the 8 lightest and the 8 heaviest pupae of each sex. When these 32 beetles had emerged, they were placed together and allowed to mate for 24 hours. Eggs were collected for 48 hours. The pupae that developed from these eggs were weighed at 19 days. This was repeated for 15 generations. The results of mate choice tests between heavy and light beetles was compared to tests among control lines derived from randomly chosen pupae. Positive assortative mating on the basis of size was found in 2 out of 4 experimental lines.
5.7 Speciation in a Lab Rat Worm, Nereis acuminata
In 1964 five or six individuals of the polychaete worm, Nereis acuminata, were collected in Long Beach Harbor, California. These were allowed to grow into a population of thousands of individuals. Four pairs from this population were transferred to the Woods Hole Oceanographic Institute. For over 20 years these worms were used as test organisms in environmental toxicology. From 1986 to 1991 the Long Beach area was searched for populations of the worm. Two populations, P1 and P2, were found. Weinberg, et al. (1992) performed tests on these two populations and the Woods Hole population (WH) for both postmating and premating isolation. To test for postmating isolation, they looked at whether broods from crosses were successfully reared. The results below give the percentage of successful rearings for each group of crosses.
WH ?? WH - 75%
P1 ?? P1 - 95%
P2 ?? P2 - 80%
P1 ?? P2 - 77%
WH ?? P1 -?? 0%
WH ?? P2 -?? 0%
They also found statistically significant premating isolation between the WH population and the field populations. Finally, the Woods Hole population showed slightly different karyotypes from the field populations.
5.8 Speciation Through Cytoplasmic Incompatability Resulting from the Presence of a Parasite or Symbiont
In some species the presence of intracellular bacterial parasites (or symbionts) is associated with postmating isolation. This results from a cytoplasmic incompatability between gametes from strains that have the parasite (or symbiont) and stains that don't. An example of this is seen in the mosquito Culex pipiens (Yen and Barr 1971). Compared to within strain matings, matings between strains from different geographic regions may may have any of three results: These matings may produce a normal number of offspring, they may produce a reduced number of offspring or they may produce no offspring. Reciprocal crosses may give the same or different results. In an incompatible cross, the egg and sperm nuclei fail to unite during fertilization. The egg dies during embryogenesis. In some of these strains, Yen and Barr (1971) found substantial numbers of Rickettsia-like microbes in adults, eggs and embryos. Compatibility of mosquito strains seems to be correlated with the strain of the microbe present. Mosquitoes that carry different strains of the microbe exhibit cytoplasmic incompatibility; those that carry the same strain of microbe are interfertile.
Similar phenomena have been seen in a number of other insects. Microoganisms are seen in the eggs of both Nasonia vitripennis and N. giraulti. These two species do not normally hybridize. Following treatment with antibiotics, hybrids occur between them (Breeuwer and Werren 1990). In this case, the symbiont is associated with improper condensation of host chromosomes.
For more examples and a critical review of this topic, see Thompson 1987.
5.9 A Couple of Ambiguous Cases
So far the BSC has applied to all of the experiments discussed. The following are a couple of major morphological changes produced in asexual species. Do these represent speciation events? The answer depends on how species is defined.
5.9.1 Coloniality in Chlorella vulgaris
Boraas (1983) reported the induction of multicellularity in a strain of Chlorella pyrenoidosa (since reclassified as C. vulgaris) by predation. He was growing the unicellular green alga in the first stage of a two stage continuous culture system as for food for a flagellate predator, Ochromonas sp., that was growing in the second stage. Due to the failure of a pump, flagellates washed back into the first stage. Within five days a colonial form of the Chlorella appeared. It rapidly came to dominate the culture. The colony size ranged from 4 cells to 32 cells. Eventually it stabilized at 8 cells. This colonial form has persisted in culture for about a decade. The new form has been keyed out using a number of algal taxonomic keys. They key out now as being in the genus Coelosphaerium, which is in a different family from Chlorella.
5.9.2 Morphological Changes in Bacteria
Shikano, et al. (1990) reported that an unidentified bacterium underwent a major morphological change when grown in the presence of a ciliate predator. This bacterium's normal morphology is a short (1.5 um) rod. After 8 - 10 weeks of growing with the predator it assumed the form of long (20 um) cells. These cells have no cross walls. Filaments of this type have also been produced under circumstances similar to Boraas' induction of multicellularity in Chlorella. Microscopic examination of these filaments is described in Gillott et al. (1993). Multicellularity has also been produced in unicellular bacterial by predation (Nakajima and Kurihara 1994). In this study, growth in the presence of protozoal grazers resulted in the production of chains of bacterial cells.
6.0 References
Ahearn, J. N. 1980. Evolution of behavioral reproductive isolation in a laboratory stock of Drosophila silvestris. Experientia. 36:63-64.
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??Return to Papers & Articles
Evidence of Evolution
Speciation: the formation of new species:
??Speciation is essentially the process of "microevolution" (mainly through natural selection), typically over many generations, during which a new population of organisms accumulates sufficient genetic, physical, and/or behavioral changes that they can no longer mate and produce fertile offspring with members of the parent population. This new population is therefore considered as a new species. As this process continues over time, more and more new species may accumulate, and at some point they can all be considered collectively as a genus (category with two or more different species that are very similar, with evidence of relatively recent divergence into species). And so on, for the ever larger groupings in the hierarchy for classifying organisms. [See Microevolution to Microevolution presentation with diagram.]
Molecular Clues to Evolution
Macroevolution: Evolution on a Big Scale
Evidence for speciation
Observed Instances of Speciation
by Joseph BoxhornCopyright????1993-2004. [Last Update: September 1, 1995]
Evolution: Watching Speciation Occur | Observations (in Scientific American online - Science Sushi)
Evidence for Evolution
The Evolution List: Macroevolution: Examples and Evidence
8 Examples of Evolution in Action
Mistakes That Argue for Evolution
Why Evolution is True
15 Evolutionary Gems (pdf)
Examples of Evolution(Understanding Evolution)
Transitional Fossils
Speciation in the Tragopogons (in the sunflower family):
??Polyploidy in Tragopogon spp. by hybridization in the wild (in eastern Washington state):
??Cross pollinatios between T. porrifolius (2n=12) and T. dubius (2n=12) produced the hybrid T. mirus (2n=24).
??Cross pollination between T. dubius (2n=12) and T. pratensis (2n=12) produced the hybrid T. miscellus (2n=24).
??Each hybrid is now self-propagating (as two new species), and neither can cross with its parent plants.
??Polyploidy (doubling the chromosome numbers) happened in a single generation.Tragopogon.spp.
---
Carl Sagan
??? Extraordinary claims require extraordinary evidence. ???
????? Carl Sagan
On 6/6/2019 3:18 PM, Mostafa wrote:
Well Carl, I certainly understand each and every term I use. What you
said about that is not acceptable. You are exercising prejudice once
again. I won't defer to these attempts to evade answering the
question. What has incredulity brought to you so far? I am quite
confident, not arrogant. People like Roger who hate religion have
reasons for that. These reasons are divided into two major categories.
Actual motives and fraudulent causes. They fallaciously claim that
science intercepts with fundamental religious propositions. They
thence submit to the doctrine of Darwinism. Well, it's just?? a theory
of organic??evolution. It allegedly claims that new species arise and
are perpetuated by natural??selection.?? . Nonetheless, this averred
hypothesis hasn't yet been examined. Each and every supposed proof has
been countered. People in the scientific community who are dare to
oppugn or oppose the Darwinian myth, are critically subjected to
redundancy and deprivation. Evolutionists act so strenuously to keep
their sacred surmisal inviolate. So, as proven numerously, science is
not the real reason for them to decline and despise faith. If anyone
acted presumptuously toward holy evolution, he is threatened with
being deposed. The theory of intelligent design is not even an option
for those people. Why? Well, because the Darwinian excogitation has
somewhat been coerced to be ecumenical. Its guardians have incessantly
inhibited anyone who just attempts to doubt or interrogate its
factuality. Each and every physical substance is made of Elements,
Atoms and Molecules. How has this rarified complexity been brought
into its current state of perfection within the theory of evolution? A
molecule is the smallest particle of a substance that exists
independently. Curiously, how has this developed arbitrarily? I never
measured scientific concepts to be of any opposition to Islam. The
Koran talks about and occasionally, refers to scientific facts such as
the consecutive phases of an embryo, as it gradually maturates inside
the womb. The Koran talks about that in details. This of course would
offend someone like Roger, the never proved Biologist, because he
hates associating faith with human science. Is there anything in
classical Chemistry, Physics or Biology that refutes the existence of
God? Theology is in fact a psychical discipline. To those who complain
about my use of vocabulary, this means settled outside the sphere of
physical??science, mainly attained with human intellectual effort and
development. I hope someone has the courage to confront what I posed.
If someone has chosen to cowardly delude himself of eh, defeating his
rival, this just counts as another form of evasion. It furthermore
proves his utterly untutored disposal. He is impious, impercipient and
hence, empiricist. Have evolutionists purposely orientated scientific
facts to make them fit their interest of maintaining mass disbelief?
What scientists say about life after death? On what basis they negate
its probability?
On 6/6/19, Carl Jarvis <carjar82@xxxxxxxxx> wrote:
Hi Roger,
What I try to point out to Mostafa is that his use of words which he
obviously does not understand, detract from whatever point he is
trying to make.
While I will never agree with Mostafa on his fundamental religious
beliefs, I would like to be able to follow his rationale...or what
passes for rationale.
I understand the difficulty of debating in a language that is not your
native tongue.
The cultural differences alone, make it very difficult to handle the
subtle nuances.?? But Mostafa projects himself to me with a "wiser than
Thou" attitude.?? I find myself wanting to give him "tit for tat", but
in sober reflection, that would not be..."the Christian thing to do".
What I envision is a cocky, brash young blind Egyptian man trying to
find his way through a difficult world.?? Maybe I'm imposing my own
early years as a newly blind man.?? I keep thinking that given time and
understanding, he will modify his rather radical religious posturing.
But, as my Grandma Ludwig used to say, "A closed mind gathers no wisdom".
Carl Jarvis
On 6/5/19, Roger Loran Bailey <rogerbailey81@xxxxxxx> wrote:
That was a bit stilted, Carl, but I am inclined to look over his word
choice until it becomes incomprehensible. I think your objection is to
what are commonly called big words. For the most part they are not
really big words. I have even heard the word id called a big word. What
they are is rare words. They are rare because they have subtle meanings
and very specific meanings and connotations that are rarely called for.
Not too long ago I was accused of using the big word peruse. I think the
person who did that did not even know the word at all and if I had known
that I would have avoided it. I explained that it meant to read and I
was asked why I didn't just say read. The reason I didn't say read was
because the specific context in which I was using it called for the word
peruse to precisely convey my meaning. The trouble was that I still did
not precisely convey my meaning if the person I was talking to did not
understand the word. But all these subtleties of word meaning are
especially prone to get lost when someone is in incomplete understanding
of the language. Have you ever learned a foreign language??? I have.
Through all four years of high school I took Spanish classes. When I
graduated I felt like I was speaking Spanish fairly fluently. But don't
expect me to translate anything for you now. I have forgotten so much of
it through disuse that now if I listen to a Spanish language broadcast
the best I can do is pick out an occasional word. I think I might be
able to pick out a few more words if they would only slow down. But as
fluently as I thought I was speaking on my high school graduation I
might not have come off that way to a native speaker. I had no native
speakers to test it on, though, so I can't be really sure. But as much
of the language as I have forgotten I seem to remember the learning
process better than what I actually learned. Part of the learning
process was memorizing vocabulary lists. Each word came with the English
equivalent. There was no attempt to define the words and certainly no
attempt to explain the specific contexts in which one word meaning
essentially the same thing should be used instead of another word.
Spanish-English dictionaries were the same except that they usually
contained more Spanish equivalents for an English word than the class
vocabulary lists did. I expect that some of these words were more rare
than others and there was no way for me to know the specific contexts in
which a more rare word should be used rather than a more common word.
You have to learn a language really well before you can start picking up
on subtleties that fine. I imagine that is what Mostafa is dealing with
when he uses a so-called big word. It can be really hard to tell which
words are the rare ones and which contexts call for the rare usage. I
will admit, though, that sometimes I do find his misuse of some words
irritating. I try to look over it, but when he uses the word destine
where he should be using either the word mean or the word intend I find
myself irritated by it. Still, though, I have to remind myself that he
probably does not have a way to determine just in what contexts the word
destine should be used. It is a little hard for me to explain it myself.
There is something that irritates me far more though. That is why he
seems to have bothered to learn English in the first place. It appears
that he learned the language specifically to use it to beat English
speakers over the head with his religion. Like I have said, there are
any number of religious people whom I have known with whom I have gotten
along with perfectly well. I don't bother them about their religion and
they don't bother me with it. One thing I have a really hard time
abiding, though, is a person who goes around harassing others with his
or her religion. That is what Mostafa does.
---
Carl Sagan
??? Extraordinary claims require extraordinary evidence. ???
????? Carl Sagan
On 6/5/2019 10:40 AM, Carl Jarvis wrote:
Mostafa,
Part of the problem here, although certainly not the central problem,
but part of it is your use of the English language.?? You have improved
greatly over the time you have been posting on Blind Democracy, but
you are still tossing out Word Salad that has little meaning.?? If you
were to use more basic language, and check with the dictionary the
meanings of the central words, you might be better understood.?? This
is not to say that your positions are acceptable to me, but they would
be clearer and allow us to discuss them more comfortably.
Below?? is a sample.?? If you can, would you tell me in American English
just what your point is?
Carl Jarvis
"why are you so baited with the subject of faith? Is it because
it urges fatuity and retardation? Or, it actually punches out
something into your perceptive conscience? You're attempting quite
strenuously to evade confronting your own scruples. Nonetheless, these
attempts are unfortunately futile. Thence, you are so rebellious,
malcontented and psychologically straitened with religion in general.
What has incredulity brought to you so far?"
On 6/4/19, Mostafa Almahdy <mostafa.almahdy@xxxxxxxxx> wrote:
Roger, why are you so baited with the subject of faith? Is it because
it urges fatuity and retardation? Or, it actually punches out
something into your perceptive conscience? You're attempting quite
strenuously to evade confronting your own scruples. Nonetheless, these
attempts are unfortunately futile. Thence, you are so rebellious,
malcontented and psychologically straitened with religion in general.
What has incredulity brought to you so far? What am I going to attain
if I'd to embrace this enormously despondent notion? I stated earlier,
despite what Carl has stereotypically prejudiced, I am flawlessly
felicitous with being religious. My faith gives me hope and aids me to
cope. Haven't any of you examined the awkward phenomenon,?? that
disbelievers are more potential to be critically suicidal than others?
What am I suppose to strive for in the rough state of disbelief? I
wish to be presented with plain answers.
On 6/4/19, Roger Loran Bailey <rogerbailey81@xxxxxxx> wrote:
You aren't being of any help right now, Mostafa. Now let me try again--
with something that I have tried over and over to help you with
before.
Without dying just how do you know that Allah exists and how do you
know
that hell exists? Try answering with the kind of answer that you have
not tried yet. Give me an answer that has something to do with it
being
true. If you cannot do that - and I think you cannot because you have
never been able to yet and no religious person in the history of
humanity has yet - then that would be a strong indication that there
is
no reason to believe it at all. But please be my guest. Become the
greatest prophet that ever lived. Be the first person who can actually
mount an argument for that absurd proposition that actually addresses
its truth. If you cannot do that it doesn't help your position one bit
to start hurling insults and to start calling names. That is exactly
what you have done before when you found one of my points
unanswerable.
This time if you cannot come up with an answer then let me help you.
If
you become ready to pay attention I will be glad to help you
understand
how to arrive at the truth.
---
Carl Sagan
??? Extraordinary claims require extraordinary evidence. ???
????? Carl Sagan
On 6/3/2019 3:59 AM, Mostafa Almahdy wrote:
Carl, when you die and go to hell, you will realise that Allah
exists.
That's the time when I won't be able to help you.
On 6/3/19, Carl Jarvis <carjar82@xxxxxxxxx> wrote:
My Dear Mostafa,
I know, without your needing to tell me, that in your eyes I am
"worthless".?? You have made that clear all along. Not just for me,
or
Roger, but for everyone who dares disagree with your "Truth".
I can only hope for a day when you awaken and realize that your
Allah
is nothing but a paper tiger, the Wizard in the Wizard of Oz.?? And
when the curtain is rolled away, you and all people of Planet Earth
will learn to trust themselves.
Cordially,
Carl Jarvis
On 6/2/19, Mostafa <ebob824@xxxxxxxxx> wrote:
Carl, you are worthless to me. That's it, adieu.
On 6/2/19, Carl Jarvis <carjar82@xxxxxxxxx> wrote:
Mostafa,
You wrote, "Religion has given my life a meaning. Yours is
absolutely
meaningless."
And therein lies the problem.?? I, as an Agnostic, do not have the
power to enter your head and tell what you think, and feel what
you
feel.?? You, as a devout Man of Allah, feel that your Absolute
Wisdom
enables you to enter my head and understand all about me, my
feelings,
my dreams and my culture.
To which I say, "Hog Wash!!!"
And by the way, my comment about my belief that you live in a more
precarious situation comes only via the news that is aired here in
the
USA.?? But if you say you live a safe life, I can accept that.
However, I am not so self satisfied as to believe that some Great
Power is protecting me.?? Even if I believed that such a Being
existed,
I am not such an important being that He would keep me safe.?? You
seem
to feel that you are such a person.?? I recall a mine accident back
around 1971, in Idaho.?? 92 miners were killed.?? Only 2 survived.
And
what did the one man say?
"God was watching over me!"?? So, God looked down and saw 94 miners
about to be killed due to the lack of safety measures by the mine
owners.?? God then said, "I can only save one or two of these
fellows."
?????? And he allowed the others to "enter the gates of Heaven".?? But
here's
a funny thing.?? The mine owners, the ones that had allowed their
equipment and tunnels to fall into disrepair, they went on living
the
Good Life.?? Mostafa, in my mind the Trinity consists of God the
Father, the Power Hungry, and Greed.?? Every religion, including
yours,
works to expand and to dominate all other religions...and all
people.
Believe what you will, but that is the sad and real truth.
This is a true fact.?? I am not dumping on religions.?? It is in the
nature of all religions.
Just the thought of looking down my nose at several billions of
people
just because they refused to believe what I believe.?? How selfish
and
arrogant!?? But it is what it is.
Cordially,
Carl Jarvis
On 6/2/19, Roger Loran Bailey <dmarc-noreply@xxxxxxxxxxxxx> wrote:Mostafa, if you are so satisfied with your life then why do you
try
to
force your religion on others and why do you throw tantrums when
you
have no refutation to a logical argument? Throwing tantrums does
not
sound like the behavior of a complacent and satisfied person.
---
David Hume
??? In our reasonings concerning matter of fact, there are all
imaginable
degrees of assurance, from the highest certainty to the lowest
species
of
moral evidence. A wise man, therefore, proportions his belief to
the
evidence. ???
????? David Hume,?? An Enquiry Concerning Human Understanding
On 5/31/2019 4:17 PM, Mostafa wrote:
Carl, I do not live a far more precarious life than you in the
United
States. Your manner of referring to my life here indicates
prejudice.
It also proves that you incorrectly assume I am affected with
any
of
the civil wars or the brutal famishments out there.
Fortuitously,
I
am
mentally confident and contented. My life is quite stable and it
hasn't been impacted with major dominance of philistinism. Roger
seems
to be somewhat your mentor. Well, good for you. He isn't more
than
just a blind embracer of empiricism. Over the course of my
constant
debates with him, I proved to?? this unworthy character his
enormous
incompetency and unprecedented nescience of basic rational
premisses.
He overused circular reasoning while fallaciously presuming it's
counterfeit to do so. Back to Carl, has incredulity solved world
junctures? As someone who doesn't believe in any form of deity
and
thence, has no purpose in life. What are you here for? I urge
you
to
search, as to why many people who do not believe, are
generically
more
potential to consider channeling suicidal thoughts and acts. Why
many
people in your glorious nation periodically jump off the Golden
Gate
Bridge? Religion has given my life a meaning. Yours is
absolutely
meaningless. The state of unjustified disbelief is a major
threat
to
natural human development. The gap broadens, as disbelievers
lose
the
discernment of the supreme aim of this life. Gradually, they
become
numb to canonical perceptions and life thereupon becomes quite
terrifying and insignificant. So, if you are struck with a
toughly
catastrophic incident, who would you turn to for aid? A friend
of
mine
lives in Britain. He tells me, that a typical worker there would
depart to the pub after his business day is over to drink. This
happens on almost a routinely fashion. They do so to distract
themselves from the arduous pressure they incessantly are
besieged
with. I as a believer never had the pressure or the stress that
demands such model of insalubrious beguilement. I am pretty
satisfied
with my life. At least, I am not threatened with someone
entering
a
public complex with a loaded rifle and insanely, shoots
arbitrarily.
I
am safe here with the grace of Allah and His providential
conservation.
On 5/31/19, Roger Loran Bailey <rogerbailey81@xxxxxxx> wrote:But you do seem to have a lot of time to waste with silly
theology.
And
it is silly. It is silly because as long as you are
contemplating
and
working out the implications of premises that have not been
proven
to
exist every bit of that work is meaningless. As I have pointed
out
before, when a fantasy writer does the same thing it is called
world
building and the more time he or she invests in the world
building
the
better the fantasy novel is. But when you just keep up the
world
building and you never write the fantasy novel you are doing
nothing
but
wasting your time. Again, Mostafa, you don't have to do this.
You
can
still give up the theology and have plenty of time left to make
something useful of yourself. You do not have to antagonize
people
all
over the Internet. You are so determined to make yourself
unpopular,
but
you really do not have to.
---
David Hume
??? In our reasonings concerning matter of fact, there are all
imaginable
degrees of assurance, from the highest certainty to the lowest
species
of
moral evidence. A wise man, therefore, proportions his belief
to
the
evidence. ???
????? David Hume,?? An Enquiry Concerning Human Understanding
On 5/31/2019 9:16 AM, Mostafa wrote:
I don't have time to waste with some bunch of rapscallions.
On 5/29/19, Carl Jarvis <carjar82@xxxxxxxxx> wrote:
In all my years as an interested onlooker, and as a reformed
Christian, I have never known God to disagree with those who
are
"Called" by Him.
The closest to that are those folks who tell me, "I didn't
want
to
do
what God told me to do, but I had no choice".
Carl Jarvis
On 5/28/19, Roger Loran Bailey <rogerbailey81@xxxxxxx> wrote:It was Robert Ingersoll who pointed out that whenever
someone
asserts
that god wants something it always agrees with what the
person
making
the claim wants. Have you ever heard anyone say, "I don't
like
this,
but
god wants it."
---
David Hume
??? In our reasonings concerning matter of fact, there are
all
imaginable
degrees of assurance, from the highest certainty to the
lowest
species
of
moral evidence. A wise man, therefore, proportions his
belief
to
the
evidence. ???
????? David Hume,?? An Enquiry Concerning Human Understanding
On 5/28/2019 8:48 PM, Carl Jarvis wrote:
Jews and Christians are one and the same religion.?? Men
wrote
down
God's Word and followed that Word for centuries.?? Then a
young
prophet
named Jesus came along, teaching as a Jewish Teacher, and
when
he
was
murdered for his crimes against the Roman Empire, his name
became
a
rallying point.?? New men wrote new rules as the Word of
God,
changed
the Sabbath from Saturday to Sunday and claimed to have a
New
Testament.?? Most of the governing Word of this new fringe
group
was
written by Saul/Paul.
If we think that government can glut the world with piles
of
rules,
laws, regulations and interpretations of all that stuff, we
should
understand that men...human people like you and me, can
write
mountains of words claimed to have fallen from the lips of
God.
But
it's all bogus.?? Just like government leveling laws to
protect
those
in power, *ALL religions set down volumes of Laws aimed at
protecting
whatever God they are backing at the time.
Life would be so much easier if we would only learn to rely
on
our
inner selves, rather than feeling the need to make up a
Superman
in
whom we are told we can place our total trust.?? And the
very
first
teaching of each of our Gods is to smite our opponents,
those
who
worship false gods.
Carl Jarvis
On 5/28/19, Mostafa Almahdy <mostafa.almahdy@xxxxxxxxx>
wrote:
Antisemitism is a major crime everywhere in the west. If
you
say
something that seems to be unfavourable to Israel and its
practices,
you will be instantly labeled as antisemite, Jew-baiter,
hater
of
Jews. Are Jews uniquely the Semite people in the Middle
East?
Not
too
many think so. They actually are claiming the smallest
proportion
of
Semite subspecieses. So, Ethiopians and Arabs, both belong
to
Semitic
descent. Nonetheless, neither of them incites western
people
if
they
were harassed or pestered. In fact, they themselves are
hassled
by
white westerns. I exposed how white western Christians are
wholly
possessed by Jews. The latter fully controls what
Christians
embrace.
Paul wrote for them a tremendous amount of their
scripture.
What
first
came in religion proceeded into politics and beyond. How
many
Christian today opposes the move of US embassy to
Jerusalem
proposed
by Trump the scoundrel? Not much of them. Christians are
ridden
by
Jews. They are not ashamed of admitting that. Jews are the
ones
who
say we crucified Christ and Christians agree with them.
So,
we
could
conveniently assert, that Christians are inspired by Jews
to
formulate
their faith for them. Therefore, if someone criticises
their
masters,
they'd call him antisemitic. Jews declined to follow
prophet
Muhammad
because he came from Ishmael lineage. They consider the
great
grandfather of prophet Muhammad a pariah. They wished the
last
messenger would have came from the posterity of Isaac.
Thence,
they
justify their hostility to all Arabs. Unfortunately,
Christians
are
codded by Jews to despise Arabs. Yes, because most of them
follow
the
prophet whom they previously rejected. Allah confirms in
the
Koran
what I stated above. Jews lead, Christians follow. This is
why,
Christians generically are somewhat constrained to comply
to
what
Jews
desire. Each and every missile?? discharged into the hearts
of
Palestinian children is paid up by US tax revenue.
Taxpayers
in
the
US
are implicitly murdering innocent civilians on virtually a
daily
basis. No one could deny this unless he has the proof for
that.
What
do Christians think of Israel? Many of them say, it has
the
right
to
exist. Despite the fact that Jews have invaded Palestine
and
displaced
its people into refugee camps, allegedly peaceful
Christians
endorse
them. I therefore urge westerns to redress their
definition
of
antisemitism. It's crucial to do so.
--
(Seeking knowledge is compulsory from cratle to grave
because
it
is
a
shoreless ocean.)
(Seeking knowledge is compulsory from cratle to grave because it is a
shoreless ocean.)
