Little bluish butterflies high in the Sierra Nevada mountains have an unusual history. Researchers report that these insects belong to one of the few animal species known to have arisen from crossbreeding of two other species.
Crossbreeding of animal species isn't unusual in itself, explains Zachariah Gompert of Texas State University in San Marcos. But the descendants of most hybrid offspring meld back into the parent species or don't compete successfully against the parental lines.
The not-yet-named butterflies in the Lycaeides genus, however, flourish in the harsh zone above the timberline, where the parent species can't cope, Gompert and his colleagues