Mitochondrial DNA variation in populations of the Mexican free-tailed bat Tadarida brasiliensis mexicana (Mollossidae)

Mitochondrial genotypes reflect an animal's female lineage; therefore, the distribution of different genotypes across the species range may be used to elucidate population structure. In Tadarida brasiliensis mexicana. the Mexican free-tailed bat, mitochondrial DNA phenotypes were used to address the question of whether the species range is divided into two separate migratory flyways, and whether bats from a single lineage show loyalty to particular breeding and/or maternity caves. Polymorphisms of the mitochondrial genome from 35 Mexican free-tailed bats were examined in this study. This included animals from four winter (breeding) roost sites in Mexico and animals from three summer caves (maternity) in the southwestern U. S. Composite mitochondrial phenotypes were constructed using DNA fragment patterns resulting from restriction enzyme digests. A total of ten enzymes were used, five of which yielded polymorphic fragment patterns. Results show that although several phenotypes were present in each cave, two main phenotypes were prevalent across the entire species range. These phenotypes were distributed among all caves sampled. These results support previous studies which found no significant genetic differences between caves across the species range. It was concluded that two separate migratory flyways do not exist and bats do not appear to be loyal to breeding or maternity caves.