[EBB Sightings] Inbreeding @ Lake Merritt

Hi Vicki,

  I'm not a duck specialist nor a phylogeneticist, but
I'll go out on a limb and say that I don't think you
need to be too worried.  For there to be a 'problem',
you would need to assume that a) the hybrid is
fertile, b) gets a mate, c) backcrosses create
maladaptive gene combinations in one or the other
parental stock.  Even if these assumptions were true,
you seem to be implying that the problem originates in
human-modified habitats like Lake Merritt.  Although
most pair-bonding in ducks does occur in the winter,
hybridization could occur through some kind of
extra-pair copulation on the breeding ground, or even
possibly mis-imprinting of a 'parasitic' egg laid by
another species (my money would be on the goldeneye
given how frequently females sneak eggs into other
goldeneye nests).

   For whatever reason, these 'distant' hybridization
events are not uncommon amongst ducks (or at least
detected much more often than for other taxa). 
However, hybridization of closely related species is
much more problematic.  American Black Duck I believe
is in trouble at least partially because of frequent
comingling with the closely related Mallard.

  Given that neither species is terribly rare, I doubt
that these uncommon events have much of any impact on
their genetic constitutions.  They could even be
beneficial, for example by introducing new variants of
genes providing disease or parasite resistance.

That's my speculative 2 cents.  Feel free to post my
reply if you want.

Cheers,

Alan






 --- vicbof at comcast.net wrote:

> This question is for the more scientificly inclined
> birders, but I was wondering if we should be at all
> concerned about the strange combinations that come
> about due to the close proximity and "looseness" of
> the birds associating with each other at Lake
> Merritt?   Could they in any way be poluting their
> own gene pools?   
> 
> -Vicki Boffin
> Sacramento Audubon
> vicbof at comcast.net
> 
> p.s.   Laura, those were excellent pictures of the
> goldeneye hybrid.

=====
Alan Krakauer, Ph.D Candidate
Museum of Vertebrate Zoology 
3101 Valley Life Sciences Building
University of California
Berkeley, CA 94720-3160
Office: (510) 642-7888 
fax: (510) 643-8238  
krakauer at socrates.berkeley.edu