Evolutionary Relationships in Macrotus (mammalia: Chiroptera) : Biochemical Variation and Karyology

Greenbaum, I . F., and R. J. Baker (Department of Biological Sciences and T h e Museum, Texas Tech University, Lubbock, Texas 79409) 1976. Evolutionary relationships in Macrotus (Mamma1ia:Chiroptera): biochemical vam'ation and karyology. Syst. 2001. 25:15-25.Genetic variation at 21 loci as determined by isozyme electrophoresis was examined from 218 specimens of Macrotus representing two species and including both mainland and island populations. Karyotypic and electrophoretic data suggest that specimens from the Antillean population (Macrotus waterhousii) are conspecific with populations of the southern mainland taxa. This high degree of similarity between Antillean and the southern mainland taxa and the tendency for the average heterozygosity of populations to be higher in peripheral populations than at the zone of contact between the two mainland species are best explained by the classical allopatric model of speciation and the data do not support the centrifugal model of speciation in this genus. A reduced degree of average heterozygosity per individual as is thought to be characteristic of island populations was not found for specimens of Macrotus from Jamaica. A decrease in variation is indicated, however, by a reduced number of loci that are polymorphic with most of the heterozygosity of the Jamaican population being in the esterase loci. The high degree of exomorphological similarity in Macrotus is not reflected in genic similarities. Macrotus display the lowest range of interspecific similarities reported for mammalian sibling species and are comparable in protein identities to sibling species of Drosophila. [Chiroptera; kaiyology; speciation; biogeography.]