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A Contact Zone Between Karyotypically Characterized Taxa of Uroderma Bilobatum (Mammalia: Chiroptera)

1975; Oxford University Press; Volume: 24; Issue: 2 Linguagem: Inglês

10.1093/sysbio/24.2.133

1076-836X

Robert J. Baker, William J. Bleier, William R. Atchley,

Animal Ecology and Behavior Studies

A contact zone between karyotypically characterized taxa of Uroderma bilobatum (Mammalia: Chiroptera) Syst. Zool. 24:133–142.—A total of 191 specimens of Peters' tent-making bat, Uroderma bilobatum, were collected from the zone where two chromosomal races, representing two subspecies, meet. Eighty-eight specimens had 2n = 38, four had 2n = 39, one had 2n = 40, one had 2n = 41, one had 2n = 42, 14 had 2n = 43, and 82 had 2n = 44. This chromosomal variation is best explained as resulting from hybridization between two cytotypes with the 2n = 38 and the 2n = 44 being the parental (pure) types, the 2n = 41 individual being of the F1 type and the 2n = 43, 42, 40, and 39 individuals representing backcross or F2 products. The two parental cytotypes were not found to be sympatric at any individual collecting station. The zone of hybridization is approximately 200 kilometers long on the Pacific versant of Honduras, eastern El Salvador and northwestern Nicaragua. Some chromosomally intermediate individuals were reproductively active although the frequency of reproductive activity was not so great as in individuals with parental cytotypes. Measurements of the cranial and wing morphology of chromosomally intermediate individuals indicated that in general there was a correspondence between chromosome number and phenetic similarity to one or the other of the two parental stocks. Chromosomal and cranial and wing morphological data suggest that there is considerable gene flow between the two cytotypes and that chromosomal divergence has occurred in the absence of speciation. The magnitude of chromosomal differentiation between the two subspecies serves as a caveat to those cases where specific recognition is based on chromosomal distinctness of allopatric samples.