Bobbleton said:
I caught two of those "integrade" rats this year . . . its funny . . . they have the patterning of a yellow rat, but that unpleasant coloration. Not knowing a ton about the area, I simply assumed they were an integrade of the immediate area being so close to yellow and black rat populations. apparantly i'm not the only one with that idea.
-Bob
IMHO the term "integrade", with its usual connotation of "hybrid" between species is far too often used when an individual of one species bears a pattern suggestive of a mix of features of the characteristically different patterns of two ostensibly separate species. In the mid 50s I had the opportunity to hatch out a clutch of eggs from a pilot blacksnake/black rat snake (Elaphe obsoleta) caught in NW Connecticut. Juvenile pilot blacks are grey with dorsal blotches and smaller lateral blotches. (As the snakes age, the grey areas darken to black, ,obscuring the underlying pattern - but if the skin is stretched, the pattern can still be discerned.) The larger dorsal blotches have concave front and rear edges, giving them a sort-of plump "H" shape - with the long limbs of the "H" running longitudinally.
Now here's the interesting part! In a couple of the hatchlings, the long sides of some of the "H's" connected thru the normally intervening grey background.
Also, in the same regions of the body, the lateral blotches were elongated and also joined. The result was that these hatchlings had regions of the body bearing the basis of a "four-striped" pattern - similar, to my way of thinking, to the pattern of the four-lined (yellow) rat snake (Elaphe quadrivittata) I made some sketches of the hatchlings patterns and took them along the next time I took a bunch of garter and watersnakes to the Bronx Zoo for trade (The zoo used them to feed cobras and other ophidiophagic snakes, and I'd go home with a few recent hatchlings of whatever non-venomous species the zoo had a surfeit.) I showed my sketches to Steve, the keeper who handled the bartering, who immediately took me upstairs to see Dr James Oliver, the Curator of Reptiles. Turned out Oliver had a thing for the genus Elaphe and was delighted to chat with a young teenager with similar interests. With regard to the longitudinal stripping, he "cut me off at the pass" by saying: "now one might think that these babys might be hybrids of the pilot black and a four-lined ... but what the Hell would a male four-lined be doing up in NE Connecticut?" I was also assured that although basic grey was often assumed to be the ground color of baby E. obsoletas, they could range from grey to light brown, to a yellowish tan - as, he said, could the hatchlings of some of the other species of the genus Elaphe. He also assured me that there was considerable variation in the time it takes pilot blacks to assume their full, mature, black (pattern obscuring) coloration, so not to be surprised by individuals with up to 2 to 3 feet in length with still-discernible patterns.
Years later, when I lived in East Texas, I saw a few Lindheimer's (Texas) rat snakes (E.o.lindheimeri) that also had partially stripped patterns.
Dr. Roger Conant, of the Philly Zoo, was also of the opinion that many species were capable of rather prominent variations in pattern, in the hue of parts of the pattern, and in color saturation without hybridization. His off-hand examples were the corn snake and the milk snake.
I'll have to admit, experiences like this one, as well as many others, have led me to the position of a taxonomic "lumper", rather than that of an energetic "splitter" who sees a new species or an "integrade" under every overturned board or rock.
As a result of the above observations and incorporated opinions, I tend to reserve the term "integrade" only for a pattern/color variant in a single species that bears coincidental similarity to a proximate species, NOT to suggest genetic hybridization between the two.
I suspect that the arguments over integrades/hybrids vs intra-specific biological variation will continue until settled for good by competent and extensive studies on DNA homologies among ostensibly closely and distantly related species.
Dave
