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

Dave Roberts dmr at
Mon Jan 8 03:55:08 EST 1996

Michael F. Hynes wrote:
>But any definition of species which is any good at all has to be
>universal, and I can't  see any way around a definition based on
>DNA homology.

I think that there are two assumptions here.  First is the belief that some
universal pigeon-hole called "species" exists, a matter about which I am
deeply sceptical.  What properties should should all units worthy of the
name share?  Indeed, why does one need an universal species concept, as
distinct from an one operating within, say, a phylum?

Second, I do not think that a simple scalar measure such as DNA homology is
adequate to the task.  Homology in some areas of the genome are probably
more important in preserving the capacity to produce fertile offspring than
others.  It may be that Michael is using a more subtle meaning for
"homology" than I am, of course.

Cheers,  Dave

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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