Whooper; Canadian geese split; paraphyly.

Laurent at Laurent at
Wed Nov 17 08:52:09 CST 2004


Ken,

> Intergrades between the two species would only have the mitochondrial
> sequences of the mother, so it is a little more complex than if they
> had based it on nuclear genes.  Sampling problems along the remote
> Arctic coast could therefore still end up making this split problematic.

This might be particularly problematic in the case of geese, actually,
because of sex-biased phylopatry. Goose pairing usually occurs on the winter
grounds, then the male most often follows the female to where it was born :
inter-population gene flow, if it occurs, is more likely to be
male-mediated. And of course, male-mediated gene flow is strictly nuclear,
mitochondrial DNA analyses cannot detect it at all...

> P.S.  The same mitochondrial DNA sequences indicate that the Hawaiian
> forms (including the extant nene goose) evolved from the larger-bodied
> species (B. canadensis)-----thus rendering B. canadensis paraphyletic.
> Does this mean strict cladists will insist that the nene goose be
> reduced to subspecies status??  Or will they just PRETEND that they
> are sister species??  [They can run, but they can't hide----paraphyly
> is nipping at their heels all over the place if they would just admit
> it].  :-)

The Hawaiian forms are sister to the large-bodied Canada geese, rendering
the *unsplit* Canada Goose paraphyletic (and, similarly, the Barnacle Goose
is sister to the small-bodied Canada geese, so the unsplit Canada Goose is
in fact twice paraphyletic ; see http://dx.doi.org/10.1073/pnas.032166399 ).

...What "they" are doing right now, is insist that the small-bodied Canada
geese be upgraded to species status...

Cheers,
Laurent


Laurent Raty
Brussels, Belgium
l.raty at skynet.be




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