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Posted by Langaha on October 19, 2002 at 07:17:09:
In Reply to: Re: Taxonomy is a matter of evidence...most of the time posted by WW on October 19, 2002 at 06:04:54:
:Not necessarily - in Bothrops and relatives, for instance, ND4 and cytb evolve at exactly the same rate, and they also evolve at very similar rates in some elapids I have worked on. Rates can vary considerably bewteen lineages, so one should not overgeneralize.
Indeed, I should not (and did not mean to) overgeneralize the usage and rates of mt genes.
:We would see more resolution *within* the three main groups of the Elaphe obsoleta complex - however, many of the ssp. would still go at right angles across the distribution of the three mtDNA cladews, e.g., traditional "E. obsoleta obsoleta" (and some of the others, I believe, but I don't have the paper in front of me at the moment)- it is very hard to see how further resolution within the three clades could recover the validity of this form.
You are also probably correct here. My point is that, with more molecular characters, I bet that we would see population structure "within" each of their identified clades (i.e., FL specimens would group with other FL specimens instead of with those from far NE localities). Then wouldn't this overlap with "some" traditional ssp? It's obvious that you and others do not want to use ssp (and I do not either for some appropriate examples), but what would we then call these populations, nothing? This is one question everyone is avoiding in my previous posts. And with sampling the Appalachian Mountains (AM) and valleys and to the SW where we believe gene flow exists, I bet that there would no longer be "distict clades" as their "barriers to gene flow" would completely break down. This is already evident at the Apalachicola River. There is no barrier here, in fact, many of us have seen E. obsoleta swimming across the river and they're commonly found on trees lining both sides. How can these be separate sp? The black phenotype probably did not evolve independently 3x, as this phenotype is also found S of the AM range extending to the north. However, mtDNA quite clearly illustrates that as glaciers retreated E. obsoleta migrated northward along each side of the AM, but gene flow still exists. Like many systematists, I don't believe these "populations" are different species.