This is another rather basic question I have.
For the traditional "Kingdom, Phylum, Class, Order,
Family, Genus, Species" heirarchy in taxonomy, only
one has a rigorous definition as far as I know. That
would be species, defined (and I understand there may
be subtleties I'm leaving out) as the set of creatures
where any male can mate with any female and produce
fertile offspring.
1) is this still regarded as basically the definition of species?
2) are there similar definitions or tests for genus? family, order,
class, phylum, and kingdom? Or are they arbitrary
categories drawn by taxonomists from genotypic considerations?
If there are rules for excluding or including a particular order from a
particular
class or a particular phylum from a particular kingdom, what might
they be? If not, what conceptual purpose do those layered categories
serve?
This gets at a point I've pursued on this list before, i.e, what
evolutionary
theory does or doesn't owe to taxonomy, and vice versa.
Thanks,
Brendan Frost