Species Concept Question

[Roger Hyam]

Richard,

This is exactly why I have difficulty with an absolutist approach to the
species (i.e. the world can be completely divided up into nice neat
units). I put forward a very similar argument in my PhD thesis in the
mid 1990's about this. If I can find an electronic copy of it I will
send it to you off list.

I see no way of choosing between the nomenclatural options you suggest.
What is more I see no way of knowing that the two extreme taxa are
sisters if you include the 'middle' taxa in your analysis. Inclusion of
your hybrid swarm in the analysis would cause the clade to collapse to a
bush. But you can't know you have a hybrid until you have defined your
taxa. But you can't define your taxa until you have eliminated your
hybrids and done a phylogeny. (cf Heller, J. 1961)  This is the nub of
the problem of why taxonomy is floundering. We can legitimately go round
and round in circles and there is no 'correct' answer. The best way to
describe the diversity is to choose one nomenclatural solution (any one)
and put notes in the margin as to what the relationships might be. This
means that for a significant proportion of diversity what we call things
is going to be more or less arbitrary.  Most taxonomists don't like to
think like this though.

Roger