[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Well, here's my two cents:
I have always had a problem with cladograms and the like, with their
nice neat straight lines diverging but never converging. I suspect
that hybridization is an important part of the evolutionary
process. When Irish deer populations were flagging someone thought
of the bright idea of importing an English species of deer (the red
deer?) to replace them. The two, thought to be different species,
hybridized, and the resulting hybrids promptly began to outcompete
both of the original populations. I recently learned that wolves,
jackels and coyotes can all interbreed to produce fertile hybrids,
in fact in some parts of North America there are entire breeding
populations of wolf-coyote hybrids. Then there are those ugly
beasts that are hybrids between yaks and cattle, that manage quite well
to breed amongst themselves. They are useful as beasts of burden
because apparently yaks do not do well at low altitudes (a bit like
the vicunas in S.America), and cattle are not at their best at very
high altitudes, yet the hybrids seem to handle both. Then of course
there are all those "species" of ducks that can interbreed genetically
(a particular problem in Australia, where domestic ducks pollute
the native genepools. Hope I didn't sound too NAZI there). Or are
ducks actually different breeds, as in dogs, rather than species?
These are just a few examples that come to mind, and two of
them are the result of human intervention, but I suspect the process
can occur naturally (like the wolf-coyotes). When I see a cladogram
(or whatever else they are called) that consists of neatly branching
lines I begin to suspect that a great generalization has taken place.
Given the nature of the fossil record, and the scale of geological
time, this is probably to be expected. But it does beg the question:
given their incomplete and greatly generalized nature, are they really
worth arguing so fiercely over? Surely one person's "mostly-guess"
is as good as another's.
(Gee, was that just 2 cents worth?)