Giving hybrids some respect
Harvard researchers are bringing new respectability to hybrids, showing that not all are evolutionary dead ends or short-lived mistakes and that some not only encompass the best traits of both parents, but create a unique mix that can endure as a separate species. Researchers at Harvard’s FAS Center for Systems Biology used genetic analysis to examine the evolutionary history of a recently recognized species of butterfly, the Appalachian tiger swallowtail, discovered in 2002. The Harvard analysis confirmed what other researchers had suspected, that the butterfly was a hybrid of the Canadian tiger swallowtail and the more southern eastern tiger swallowtail. Further, the researchers showed that the hybrid species originated when males from the Canadian species mated with females from the south. “Our work provides perhaps the first animal example that illustrates how hybrid species may be selectively favored when they inherit from their parent species-specific combinations of genes that underlie important ecological...