Posted by:
Terry Cox
at Sun Mar 20 16:39:24 2005 [ Email Message ] [ Show All Posts by Terry Cox ]
>>I always wondered what the criteria were for claiming that something was a subspecies rather than a separate species. For example, what exactly is it that makes o. quadrivatta (is it quadrivattUS now? I'm assuming it is, but correct me if I'm wrong) a subspecies of o. obsoletus? Why couldn't it be quadrivattus quadrivattus? Is it that o. obsoletus has the larger range, or are there DNA tests or something?
Taxonomy was always using morphological characteristics in the past. Now people are trying to rearrange things according to dna. Elaphe obsoleta, as well as other species, such as Elaphe guttata, had subspecies based on some identifiable characteristics which were consistently different from the main subspecies. These subspecies normally intergrade along their boundaries.
Sometimes there's problems with whether or not subspecies are actually intergrading along a common boundary. For instance, there has been a lot of argument through the years on whether or not Elaphe g. guttata and E. g. emoryi are subspecies or separate species, E. guttata vs. E. emoryi. It seems to me that they would be subspecies if there were a common boundary where they were intergrading. If there's an intergrade zone, I think they should be considered subspecies. If there's isn't an intergrade zone, they should be considered distinct species. That still remains to be seen because not all the evidence is in, yet, especially considering the dna that needs to be looked at.
With E. obsoleta, Burbrink is trying to show dna evidence for separate species, plus the fact they are not intergrading. This has not been widely accepted, and I do not. I do believe that there is intergradation, and I also believe in the subspecies concept. Think about what it would mean, if noone recognized any subspecies.
TC
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RE: Quick question while everyone's talking taxonomy. . . - Terry Cox, Sun Mar 20 16:39:24 2005