Re: webbing

John Wilkins (wilkins@wehi.edu.au)
Wed, 12 Jul 1995 14:35:06 +1100

In article <3tufcj$il9@geraldo.cc.utexas.edu>, Alex Duncan
<aduncan@mail.utexas.edu> wrote:

: Well, another one bites the dust.
: I just took a look at one the baboons in our freezer, and the
: webbing between her fingers was just as extensive as the webbing between
: my fingers. I'll be posting JPEGS as soon as I can shave her hands and
: pry her poor dead fingers apart long enough to get a picture.
: Also, in "Gorillas in the Mist", Diane Fossey notes that some the
: gorillas at Karisoke (sp?) have EXTENSIVE webbing between their fingers.
: Its true that the very extensive webbing results in part from the fact
: that the mountain gorillas are an inbred population, and recessives are
: more likely to be expressed. But, THE GENE FOR IT HAD TO COME FROM
: SOMEWHERE. Perhaps (I'm just guessing here), the potential for webbed
: digits is a genetically ancient trait, going back to Icthyostega and
: Acanthostega.
:
:
OK, here's a totally uninformed, vaguely remembered, response. As I
understand it, the webbing between fingers is the result of ontogenetic
processes of apoptosis (programmed cell death) during the fetal
development. The hand starts out as a bud, and the tissue between the
fingers stops replicating, while the fingers continue to develop. Webbing
is the result of apoptosis failure. The likely cause of webbing is
therefore something in specific ontogeny rather than genetic. This *could*
be a holdover from phylogenetic ancestry (Haeckel's dictum), but only in
the general sense that the expression of vertebrate genes follows a broad
pattern. However, as a complete ignoramus in this area, I may be unaware
of genes regulating the apoptosis, so who knows. Perhaps webbing, as
opposed to environmental perturbations of fetal growth, *is* genetically
regulated, in which case it would be subject to selection pressures.

Anyone better informed than I am? Let me rephrase that -- anyone know more
about this topic than I do?

-- 

John "Chris" Wilkins, Assoc. Prof. of Recent Runes, Uni of Ediacara

Also: Head of Communication Services, Walter and Eliza Hall Institute

Home Page: http://www.wehi.edu.au/~wilkins/www.html 

I'd be willing to argue that point (said the arachnid to the dipteran) - Chris Colby on talk.origins