Thursday, June 23, 2005

ENV: Bilateral Gynandromorph

While we're talking about the sexual proclivities of invertebrates, i thought i'd throw in something else.

In the 1970's, a researcher with the Chihuahuan Desert Research Institute picked up an American Kestrel, Falco sparverius, that had been hit by a car, and brought the specimen to me at the Department of Biology at Sul Ross State University (i was research director at CDRI and teaching in the department at the time).

I had a student prepare the specimen and place it in the collection. It had been frozen and i did not look it over very closely except to identify it and pass it along. Not long thereafter i came across the specimen in the collection and, with Steve West, noticed something rather odd about it. If you lay it on it's left side it appeared to be a female. If you lay it on it's right it appeared to be a male.

Examining it a bit more closely you could see that it was split right down the middle dorsally and ventrally -- and it was easy to see because American Kestrel is one of the few Falconids that is markedly sexually dimorphic (that is, the sexes differ in coloration and patterning -- in most raptors this dimorphism is limited to differences in size). This bird even had half it's tail feathers slightly shorter than the others, the same for the wings. The colors of each were intact on the respective sides.

These anomalies, known as bilateral gynandromorphs, are known in several other species of birds, and in other vertebrates. We attempted to publish this record, complete with a fine series of pictures. The paper was rejected however. According to the reviewers a true gynandromorph is one in which the internal cell-producing organs (the ovaries and testes) are bilateral, and since the carcass had been discarded and not dissected there was no way to know if our specimen was indeed a true gynandromorph.

My fault, of course, for not checking the specimen more closely before turning it over.

That was some time ago, and i don't remember the details my literature search turned up, but i was surprised to find an invertebrate gynandromorph pictured on the blog The Biology Refugia today. It's a Blue Crab and you can read more about it here.

Here's an enlarged picture of the creeper.

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