Sex and Species- A Question (was Re: sex)

Dave Roberts dmr at
Fri Jan 5 04:44:03 EST 1996

Michael F. Hynes wrote:
>This definition, while not without its flaws, has the virtue of
>general application to all organisms. After all when we talk about
>defining animal species based on "interbreeding to produce fertile
>offspring", aren't we really talking about sufficient DNA homology to
>generate chromosome pairing (and recombination ?) ?

I don't think it is as simple as this (is it ever??).  Many, if not all,
animal species have many other barriers that have to be matched and
compatible before the opportunity for chromosome pairing presents itself.
Consider the failure rates in IVF when sperm and egg are brought into
artificial contact.

I think that this definition will be far looser than those accepted in the
animal kingdom now.  It is an interesting question why the class Insecta
should have somewhere in the region of 3 to 30 million species, yet there
are only thought to be thousands of species of prokaryotes.  The
prokaryotes are undoubtedly more genetically diverse, but there must be a
better way of expressing that diversity than counting species.

Dr D.McL. Roberts,        Tel: +44 171 938 8790
Dept. Zoology,            Fax: +44 171 938 9483
The Natural History Museum,
Cromwell Road,
London        SW7 5BD
Great Britain             Email: dmr at

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