[Taxacom] Giraffe "cryptic" species????

[Kenneth Kinman]

Hi All,
      I was just rereading my post from last night, and am concerned
that it was probably misleading to say that giraffes in Kenya may
display a "complex and confusing hybrid swarm of sorts".  If there are
actually two separate species of giraffe (whose ranges meet in Kenya),
it would be more accurate to characterize that confusing complexity as a
combination of both hybridization (between species) AND intergradation
(between subspecies).  It would not be a typical hybrid swarm, since
there are almost certainly some kind of selective pressures at work in
giraffes creating geographical variation that appears to be rathered
structured (especially among females), even within Kenya (at least in
recent times).    
       However, I can't help but wonder if the results would have been
somewhat different if Y-chromosomal genes had been studied (instead of,
or better yet, in addition to, the mitochondrial genes).  As in humans,
where the "mitochondrial Eve" is considerably older than "the
Y-chromosomal Adam" of human evolution, I suspect giraffe males
wanderlust would also show a somewhat different pattern from that of the
females, and the times of  divergence of populations of giraffes were
overestimated in the study by Brown et al., 2007.  The smaller
mitochondrial genomes (passed down in only female lineages) may be
easier to sequence (and thus more commonly are), but the Y-chromosomal
genome (passed down in only male lineages) may be far more informative
for many species.  Therefore, we may see a much different result when
Y-chromosomal genes are sequenced for the same populations of giraffes.         
      In any case, the largest division of giraffes based upon both
morphology AND the available molecular data clearly show the biggest gap
is between giraffes from southern Kenya to the south, and giraffes from
northern and western Kenya to the north and west.  Roughly speaking the
dividing line is the equator.  Whether these are really two separate
species remains to be seen, but I am still highly skeptical that there
are more than 2 species of giraffes.  And I would also be very reluctant
to call them "cryptic".
               ---------Ken Kinman                
----------------------------------------------------------
Dear All, 
     There was lots of discussion about cryptic species in the latest
thread.  Looking at one actual concrete example today, I wonder if the
phrase "cryptic species" is a bandwagon which is increasing being jumped
on (but perhaps not always appropriately).                
        The example I was looking at was the giraffe, which in the past
several years has been branded by some conservationists as a complex of
MANY different "cryptic" species.  From what I have read so far, one
could actually easily argue that there are indeed two separate species
of giraffe (southern and northern) which meet in the area of Kenya
(where there is a complex and confusing hybrid swarm of sorts).   It is
just such a middle ground from which I plan to approach the problem.
However, a bunch of molecular guys seem more intent on taking it
further, and claim that there are six or more separate SPECIES of
giraffe.  Even more disturbing is that they call these "cryptic
species".  Seems odd to me calling populations that are both
morphologically distinct (at least in pelage pattern) and somewhat
genetically distinct as "cryptic".  Polytypic seems a more appropriate
term than cryptic.    
        Anyway, I am very open to recognizing two separate species of
giraffe (one southern and the other northern), but as for splitting
giraffes into a bunch of other separate species, I am rather skeptical.
There's a lot of variation in pelage pattern and some minor genetic
differences, but I am VERY concerned that they are going to carry their
splitting tendencies too far.  One of those typical pendulum swings that
I really hate to see. 
          ---------Ken Kinman       
P.S.  I can understand that these splitters have conservation concerns.
However, the two subspecies of giraffe with the lowest population
numbers (in the north) are already listed as "Endangered".  Trying to
raise such populations to species status (only subspecies within the two
giraffe species that I might tend to support) would only marginally
affect their survivability, and at the same time seems scientifically
marginal as well.  Their time might be better spent emphasizing the
importance of saving such endangered subspecies, rather than insisting
that they are separate species.  Otherwise they risk being marginalized
when further scientific data shows their splitting to be excessive.  I
fear that the pendulum continues to swing widely, too often more than is
good for anyone concerned.