[Taxacom] Evolution of molluscs and other invertebrates

Dr. David Campbell amblema at bama.ua.edu
Fri Jul 10 18:08:23 CDT 2009

Quoting Bob Mesibov <mesibov at southcom.com.au>:

> Richard Petit wrote:
> "Don't forget that Mollusca has bivalved gastropods."
> Candidate  case for horizontal gene transfer of developmental genes?

No.  The details of bivalved form are rather different.  In particular, 
the snails start out with a fairly normal single shell before starting 
to grow the second valve.  I think a recent paper actually looked at 
some key developmental genes and found the pattern to be different.  
Bivalved body plans turn up here and there in several taxa (various 
Crustacea, Brachiopoda, diatoms, etc.)

There are also good transitional forms in the early Cambrian mollusks 
going from single shelled to bivalves.  

Dr. David Campbell
425 Scientific Collections Building
Department of Biological Sciences
Biodiversity and Systematics
University of Alabama, Box 870345
Tuscaloosa AL 35487-0345  USA

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