Ocean Channel in Bahamas Marks Genetic Divide in Brazilian Free-Tailed Bats

Brazilian free-tailed bats are expert flyers, capable of migrating hundreds of miles and regularly traveling more than 30 miles a night. But they pull up short at a narrow ocean channel that cuts across the Bahamas, dividing bat populations that last shared an ancestor hundreds of thousands of years ago. A new study, published online on August 17, 2017, in Ecology and Evolution, uncovers a dramatic and unexpected genetic rift between populations of Tadarida brasiliensis on either side of the Northwest and Northeast Providence Channels, about 35 miles across at their most narrow point. Genetic analysis of the populations suggests that bats from Florida colonized the northern Bahamian islands while bats from other parts of the Caribbean likely colonized the southern Bahamas. The open-access article is titled “Population Structure of a Widespread Bat (Tadarida Brasiliensis) in an Island System.” Why the bats balk at crossing a channel so narrow they can likely see land on the other side while in flight remains a mystery, said Kelly Speer, the study's lead author who completed the research while a master's student at the Florida Museum of Natural History. "Based on their mainland population behavior, we know they're able to disperse much farther than the distances between islands in the Caribbean," said Speer, now a doctoral student at the American Museum of Natural History. "It doesn't seem like distance is the factor, and there's no association with wind direction. We don't have any idea why they don't cross this channel." Because they can fly, bats are good models for studying mammal movement in fragmented habitats, Speer said. The ability to disperse, or spread genes by moving to other areas, plays a key role in the evolution of animal populations, and a barrier to bats' dispersal is likely a barrier to less mobile animals.
Login Or Register To Read Full Story