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

Michael F. Hynes hynes at
Mon Jan 8 13:13:24 EST 1996

dmr at (Dave Roberts) wrote:

>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?
The problem here is what is a phylum ?  If you believe systematics and
and taxonomy have any value at all (a moot point; I think they are
valuable if they are an accurate reflection of phylogeny) you have
to define exactly what the taxa are.  Especially if you work with
bacteria, as  I do, it is easier to define things at the ends of
the scale (Domains and Species) than to talk about phyla, classes,
orders etc.  The species concept is so embedded in biology by
now ("origin of species" etc) that an attempt to define more
precisely what a species is seems a worthwhile endeavour to me.

In my original post, I suggested that if two organisms were sufficiently
related to allow homologous recombination to take place between them
over substantial regions of their genome, then they should probably
be regarded as belonging to the same species. I would like to know
what people think of that concept. Is there anything substantially
wrong with it ?  I don't think it upsets current notions of what species
are in the animal and plant world. And it does include the vast number
of organisms, which due to the fact that they do not reproduce
sexually, cannot be fitted into the "interbreeding" scheme of things.


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