I just spent an hour on a reply (when I should have been doing other things), only to have it disappear on me. This one is going to be much shorter and succinct (which is probably better, anyway). What I've written below is particularly applicable to Lampropeltis triangulum, as that is our topic.



Subspecies aren't a tenable biological entity – they aren't separate, but rather part of the whole. Milksnakes (Lampropeltis triangulum) are perhaps better (more realistically) viewed as a clinal species, which changes across its broad range in response to local environmental conditions. That said, subspecies are very useful in describing the various within the species. Where a particular set of characteristics (morphological and/or genetic) is fairly consistant over a fairly broad geographic area (often coinciding with a major ecological region, like the Great Plains), we recogzine a subspecies to denote that population.



Subspecies DO NOT overlap and I wish field guides would stop describing them that way. Areas of intergradation are actually areas of non-differentiation. The animals are intermediate, both phenotypically and genetically (duh, I know) between the subspecies on either side. As I stated above, I had an eloquently laid-out explanation with good examples, etc., but that's all gone. Sorry. In short, I had described the habitat and range of the Lampropeltis triangulum gentilis (essentially, arid shortgrass prairie) and L. t. syspila (esssentially mesic forest glades and tallgrass prairie). Between them is an area of intermediate and trasitional habitat: The Flint Hills. In the Flint Hills, one finds milksnakes intermediate between gentilis and syspila. On the western flank, they look more like gentilis, while toward the east, they show more syspila traits. Intermediate habitat = Intermediate (intergrade) milksnakes.



As for conservation, the goal is to generally preserve variety. If milksnakes are only in trouble in New Jersey because of over development, does that mean we shouldn't try to preserve them because they're doing well in Kansas or Missouri? Of course not – a shrinking range and loss of habitat is bad for every species. Is the doom of the New Jersey animals going to spell it out for the rest of the species, too? Probably not, but it's not good in any way, shape for form.



All subspecies of a given species are are adjacent to one another "interbreed". If they don't, they're not subspecies, they're species. Period.



Here's a west-central Kansas gentilis, since everyone likes pictures.

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-Cole

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