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Posted by WW on October 19, 2002 at 06:04:54:
In Reply to: Re: Taxonomy is a matter of evidence...most of the time posted by Langaha on October 18, 2002 at 07:22:37:
:I knew we were thinking the same way for the most part. Although they sequenced 2 mt genes, they only used 1 to create their phylogeny because the d-loop (the 1 they supposedly sequenced) was useless to include. Not surprising for snakes (also see the Nerodia clarkii study). There have been other studies recently that have show the limitations of cyt b for recently evolving populations, ND4 is faster evolving and shows much more resolution at the population level
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.
: (some clades actually overlap with some recognized ssp in the eastern US, while cyt b only shows the same pattern for these snakes as the Elaphe obsoleta study). If these snake species shared a similar evolutionary history (as we suspect due to glacial events and present distribution) then we should expect that ND4 could also give us more resolution between populations. I know this may be wordy, but I am rushed with work today. I just feel that if they had more molecular characters (with ND4 or other genes) than we might see some better resolution for the group.
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.
Cheers,
Wolfgang
