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Speciation, Heterochrony, and Genetic Variation in Hispaniolan Palm-Tanagers

1990; Oxford University Press; Volume: 107; Issue: 4 Linguagem: Inglês

10.2307/4088001

1938-4254

Mara A. McDonald, Michael H. Smith,

Animal Ecology and Behavior Studies

We documented levels of genetic variability for two species of Hispaniolan palm-tanagers. Significant differences between age classes in levels of genetic heterozygosity were concordant with an age dimorphism in foraging behavior and morphology in Phaenicophilus palmarum; juveniles (H = 0.121) were almost twice as heterozygous as adults (H = 0.074). Phaenicophilus poliocephalus (H = 0.104) was not characterized by a distinct age dimorphism in any character examined. Although P. poliocephalus resembled juvenile P. palmarum in morphology and behavior, it was not significantly different from either adult or juvenile P. palmarum in levels of genetic variability. Both species of Phaenicophilus possess levels of genetic variability (9-10%) that are high for birds, and they differ in allele frequencies and presence of private alleles, although they are not characterized by fixed allelic differences. Phaenicophilus poliocephalus was probably derived from small founding populations (ca. 50,000-260,000 yr BP), composed mostly of juvenile P. palmarum that colonized the south island of Hispaniola formed during the Pleistocene. Rapid divergence between species is consistent with predictions from models of heterochrony by paedomorphosis and speciation by a founder event.