Re: Evolution: A few questions

David,

I am also intrigued by the analogy of the survival of evolutionary transitional forms and the survival of metamorphic forms. I think that the differences between the two cases need to be clearly thought through:

1. Modern metamorphic changes are well orchestrated by complex genetic instructions that apparently have been in place for quite a while. True evolutionary transitions would appear to have no such internal controls to keep the critter alive. The exact process that allows a tadpole to survive the transition from herbivore to carnivore are probably rather complex.

2. (I don't know about this one) In metamorphosis, the end result is "known" or purposeful, while in evolutionary transitions, there is no goal (TE could insert something here).

Al McCarrick

-----Original Message-----
From: bivalve [mailto:bivalve@mail.davidson.alumlink.com]
Sent: Tuesday, June 22, 2004 18:59
To: ASA
Subject: Re: Evolution: A few questions

> > In contrast even to a benign remodel, let me note what happens during the
> > metamorphosis of a frog.

An additional remodeling that occurs in the development of most tadpoles is the change from a vegetarian to a carnivore gut (relatively long to relatively short, etc.). Some species are able to make the change early, if algae is in short supply. In particular, certain species that breed in temporary ponds have tadpoles that are able to turn into cannibals if the pond is starting to dry up. This gives them an abundant supply of food so that they can grow fast and complete the tadpole stage before the pond dries up.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL 35487-0345 USA
    bivalve@mail.davidson.alumlink.com

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
Received on Wed Jun 23 14:53:13 2004