Re: Species [arbitrary to a degree]

[AM Yates <Adam.Yates@bristol.ac.uk>]

On Mon, 22 Oct 2001, chris brochu wrote:

> Something I once heard from Dave Hillis - ability to interbreed is 
> the ancestral  condition, inability is derived.  There are cases 
> where distantly-related frog  species can interbreed, but 
> closely-related forms  within the same clade cannot.
> 

This is exactly what I was going to say - the ability to interbreed is a
symplesiomorphy. To add one more example, this time with a little
quantification,the two Australian skinks Tiliqua scincoides and Egernia
cunninghami can interbreed (offspring healthy and survive to adulthood). 
The genus Tiliqua is an highly apomorphic clade with a fossil record
stretching back to at least the Oligo-Miocene boundary. Thus these two
lineages have maintained the ability to interbreed even though they
diverged at least 25 million years ago (with one lineage clocking up a
lot of morphological transformation to boot). 

cheers

Adam