Literaturdatenbank
Literaturdatenbank |
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Harding, J. H. Brief comment on wood turtle geographic skin color combos. (to: Y. G. Clemmys).
Added by: Admin (14 Aug 2008 20:36:23 UTC) |
| Resource type: Personal Communication BibTeX citation key: Harding2003 View all bibliographic details  |
Categories: General Keywords: Clemmys, Emydidae, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Systematik = taxonomy Creators: Clemmys, Harding |
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| Abstract |
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Clemmys inscupta From what I've seen, there is (or was) a real west to east trend, with the far western pop in MN being almost entirely yellow, MI ones being mostly yellow to yellow-orange, and PA and ONT being largely dull to bright orange, with increasing "salmon" red pigment infusion as you get farther east into New England, upstate NY, and the maritimes. The extreme edges of the range are fairly consistent (yellow in west, reddish to reddish-orange in the east), thus I've only seen yellow in MN, and the ones I've seen from NS and NB were predominantly red-orange to salmon-red. But the center of the range is more variable within the basic statistical trends-- I've seen a few notably orangy specimens in MI, and one or two rather dull yellowy-orange ones from W. PA. My guess is that we are seeing the result of at least three isolation events (refugia) during the Pleistocene ice-events, now coming back together and slowly mixing it up. And we have to make allowances for the fact that humans have carted these animals around and released specimens far from their origins, thus speeding up the natural pace of introgression. (There are also "trends" in carapace color, shape, and pattern, but I won't get into that here.) Thus, if someone shows me a very yellow wood turtle, it would very likely be from the western Great Lakes, and would certainly not be from the eastern seaboard, or New England or Nova Scotia. A very dark-shelled "salmon-red" woody would almost certainly be from the northeastern part of the range, and certainly not MN or northern MI or WI. But plain-orange-colored one could be from almost anywhere in-between. A turtle with only "yellow" skin pigment is unlikely to occur (naturally) east of central PA, and I've never seen the true red to salmon-red pigment in turtles from MN, WI, MI, W. ONT, or W. PA. I'd appreciate comments from other observers. Years ago I and several colleagues tried to use standardized photographic techniques and published color tables to study and illuminate these regional color trends. Sadly, this effort died with the untimely passing of Jack McCoy; I'm not sure that we would have been successful in any case, as "color" is quite subjective and most difficult to quantify.
Added by: Admin |