Sunday, December 03, 2006
High in the Sierra Nevada mountains, a new species of butterfly has emerged as a hybrid of two existing species. It is the first time that this type of species formation has been shown in animals, according to the report published online December 1 in Science Express.
"Darwin published 'On the Origin of Species' in 1859, but we are still learning about the ways new species can form," said Arthur Shapiro (info), professor of evolution and ecology at UC Davis and co-author of the paper. This type of speciation has been shown in plants, but never in animals, he said.
Lycaeides melissa butterflies live on the eastern side of the Sierra, and Lycaeides idas live to the west. In between, in the harsh climate above the tree line, is a third, alpine species of Lycaeides.
Zachariah Gompert, a graduate student at Texas State University, with James Fordyce at the University of Tennessee, Knoxville; Matthew Forister at the University of Nevada, Reno; Shapiro; and Chris Nice at Texas State, used molecular genetics techniques to show that the hybrid alpine butterflies carry a unique mix of genes from both parental species. There is no gene flow, or interbreeding, between the parent species and the hybrid.
Continued at "Hybrid Butterflies High in the Sierra"
Based on the journal Science paper "Homoploid Hybrid Speciation in an Extreme Habitat":
Theory predicts that homoploid hybrid speciation, which is hybrid speciation without a change in chromosome number, is facilitated by adaptation to a novel or extreme habitat. Using molecular and ecological data, we show that the alpine-adapted butterflies in the genus Lycaeides are the product of hybrid speciation. The alpine populations possess a mosaic genome derived from both L. melissa and L. idas and are differentiated from, and younger than, their putative parental species. As predicted, adaptive traits may allow for persistence in the environmentally extreme alpine habitat and reproductively isolate these populations from their parental species.
Opening paragraphs of Dateline UC Davis' interview with Arthur Shapiro, "Breaktime: Arthur Shapiro - Talking butterflies and politics" (January 17, 2003):
Arthur Shapiro looks like he jumped out of a Woody Guthrie folk song. At first glance, few would guess that the grungy Shapiro was a professor in entomology, evolution and ecology, let alone one of the world's foremost experts on butterflies.
"It's disarming to look the way I do," he said. "People's perception of me is not necessarily who I am. I like being unpredictable."
The only thing predictable about Shapiro is his constant search for butterflies and his ability to deliver meaningful research on topics such as the decline of California's butterfly population. He's often in the field looking for the delicate creatures that stir his imagination in so many ways...
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