[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Paradoxically temporal

>Well, the bottom line is:  Do we have *any* data that indicates what species
>concept is correct??

I'm not sure it's a matter of throwing data at them.  Part of the reason
there's controversy at all is that we have data.

As for my own approach, I was impressed by something Dave Hillis once said
in a seminar - we have three concepts in general use (biological - a
species is a reproductively isolated population; evolutionary - a species
is a cohesive lineage with its own historical fate; phylogenetic - a
species is the smallest diagnosable unit in a phylogenetic analysis), we
can see them all as part of the same thing.  One describes what a species
is, one describes how we recognize it, and the third describes one way a
species becomes a species.

Think about it - very few people actually use reproductive isolation to
discern species, even though that's the concept that gets the most
recognition.  This is especially true for paleontologists - do we really
know that different Hell Creek ceratopsians were not capable of
interbreeding?  What we actually use is something like the phylogenetic
concept - we diagnose 'till we can't diagnose further without running into
variation, which we infer as intraspecific or intrapopulational.

So a species, ultimately, is the smallest lineage bound by reticulation or
gene flow, and with its own historical tendencies; we recognize it through
diagnosis; and reproductive isolation is one way to generate a species.


Christopher Brochu

Postdoctoral Research Scientist
Department of Geology
Field Museum of Natural History
Lake Shore Drive at Roosevelt Road
Chicago, IL  60605  USA

phone:  312-922-9410, ext. 469
fax:  312-922-9566