[Taxacom] Semantic Web: What is a species?
kennethkinman at webtv.net
Sat Jan 24 22:21:57 CST 2009
I don't think you can generalize by saying that taxonomists have
a particular view of the reality of species. I am a taxonomist, not an
ecologist (or other specialized user of taxonomy). Yet I agree with you
that species are more real than subspecies, genera, or families.
I certainly understand Richard's view that species are also human
constructs, but I think that they have an evolutionary cohesiveness that
makes them more "real" than other taxa. They certainly can have fuzzy
boundaries (especially when they have just split from another species),
and I think that is why I tend to lump more than I split. When they are
close to that speciation event (on one side or the other), it is very
difficult for us humans to know if they have really crossed that line
In fact, it can't be known with absolute certainty because we
have no knowledge of future events (contingencies) that could either
push these marginal cases completely over the species threshold or force
them back together where gene flow resumes to a significant degree. I
think polar bears are a great example of this. They clearly evolved
from brown bears, but we just don't know whether there will be any
significant resumption of gene flow as their breeding areas are forced
to overlap more and more.
I really like to think of species that are close to splitting as
being sort of like two oxygen atoms in an excited oxygen molecule. They
still share those outer electrons that bind them together (= gene flow),
but something eventually comes along that finally breaks those bonds.
It's not a perfect analogy, because real species usually don't come back
together after a certain point (whereas oxygen atoms could do so more
easily), but it should give one an idea what I am getting at. Anyway,
that is my two cents worth.
P.S. I think one reason that Richard and I see it somewhat differently
might be because I study land animals and he studies fish. I think that
fish species in the ocean generally have a little more fuzziness to
them, and that it is perhaps a bit harder for barriers to develop that
force one species to develop into two.
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