It isn’t not an easy problem to solve, what constitutes a species, that is. Nor
is it easy to determine what exactly leads to generation of lineages
sufficiently distinct for us, as humans, to call them separate. Instead of
distinct categories that are easy for us all to talk about with each other,
there are many, many lineages in a variety of stages of shifting to and from
“independence” or “distinctiveness.” Our rapidly improving understanding of
genomics is shedding new light on, and creating new confusion about, what makes
a species distinct and what leads to speciation.
And confusion is exciting, not scary. Confusion means we have more to learn.
Confusion means there are remarkable new discoveries to make, new theories to
develop, new insights about the world to reveal. Confusion means we are not in
full possession of coveted knowledge yet.
Regarding the mate selection issue, there is a new and very interesting theory
on speciation developed by Geoff Hill called mitonuclear speciation. It
examines the interactive roles of the mitochondrial genome with the nuclear
genome in speciation. It is very interesting and likely works very well in
birds. Google search the phrase and Geoff and you can find his most recent
paper in the Auk.
Always something new and amazing to learn about birds that we see every day!
Doug
On Jan 20, 2018, at 6:39 AM, David Irons <LLSDIRONS@xxxxxxx> wrote:
Interestingly, a couple days ago I was involved in a discussion with David
Vander Pluym (on Facebook of all places) about Cassiar Juncos and the utility
and accuracy of the trinomial "cismontanus." He cited work done by Alden
Miller 70 years ago which proposed that there were breeding populations of
Cassiar Juncos mating only with other other Cassiar Juncos independently of
any backcrossing with either Oregon or Slate-colored Juncos, thus resulting
in a "pure" (and I use this would quite loosely) population that one could
call a subspecies. I have a hard time wrapping my head around the notion that
a phenotype originally produced by the interbreeding of Oregon and
Slate-colored Juncos across a broad zone of contact can then become a
subspecies without any isolating evolutionary mechanisms other than mate
selection. All the while, Miller noted that some of the subpopulations of
Cassiar Juncos continued to routinely backcross with apparently pure Oregon
and Slate-colored Juncos. How does one quantify the frequency of inputs from
new F1 hybrids or determine at one point sufficient independent breeding has
occurred to produce a true "subspecies?" Made my head hurt.
Dave Irons
Beaverton, OR
From: obol-bounce@xxxxxxxxxxxxx <obol-bounce@xxxxxxxxxxxxx> on behalf of W.
Douglas Robinson <w.douglas.robinson@xxxxxxxxx>
Sent: Saturday, January 20, 2018 1:23 AM
To: deweysage@xxxxxxxxxxxx; OBOL
Subject: [obol] Coastal crossbills
Dave,
If you search scholar.google.com for Red Crossbill, I think you will find
links to dozens of research articles, many of which are based on both
observation and experiment. The work from Craig Benkman and his colleagues is
especially strong and insightful.
Crossbills are difficult to study. That is why only Cassia Crossbill in North
America has been split. It is hard to demonstrate assortative mating in the
field. The other types are not known in sufficient detail to demonstrate
limited gene flow; yet. That is part of what makes crossbills a fun problem
to solve. How many cryptic species might there be? None? One more? 10 more?
I am unaware of any evidence that individual crossbills ever utter more than
one flight call type. I think we can feel good that, if it happens, it is
rare, based on thousands of hours of observation and hundreds of recordings.
It is obvious that most crossbills eat more than one species of conifer seed.
There are at least 5 types eating Sitka Spruce on the Oregon Coast now. All
of those except type 10 are thought to specialize on other species besides
Sitka. Specialization does not mean exclusivity. There is good scientific
data showing that bill morphology influences efficiency of seed extraction
depending on the match of cone morphology and bill size and shape. One can
eat food from other crops even though one is not very efficient at it. You
can eat nectar from honeysuckle if you’re in a pinch but hummingbirds are
obviously far more efficient at it.
This is a well studied group of birds yet we still have much to learn.
Doug
POST: Send your post to obol@xxxxxxxxxxxxx <mailto:obol@xxxxxxxxxxxxx>
JOIN OR QUIT: //www.freelists.org/list/obol ;
<//www.freelists.org/list/obol>
FreeLists / Oregon Birders Online <//www.freelists.org/list/obol>
www.freelists.org <//www.freelists.org/>
OBOL is a listserv dedicated to birding in Oregon, including, but not limited
to, rare bird alerts, unusual bird behavior, inquiries for species locations,
and upcoming birding events in Oregon.
OBOL archives: www.freelists.org/archive/obol
<//www.freelists.org/archive/obol>
Contact moderator: obol-moderators@xxxxxxxxxxxxx
<mailto:obol-moderators@xxxxxxxxxxxxx>
