The efficacy of sex-chromosomal markers in studies of Cercopithecus hybridization: Discovery of a captive hybrid and applications in wild populations.

We demonstrate the utility of previously described molecular methods for identifying hybrid Cercopithecus monkeys. Using phylogenetic analyses and DNA sequence comparisons at X-chromosomal and Y-chromosomal loci, we have identified a hybrid animal in the Cheyenne Mountain Zoo (USA)--an identification that was not known a priori but was later confirmed by review of zoo records. The molecular techniques employed here are of great use to studies of the genus Cercopithecus because, unlike most mammals, these monkeys frequently form polyspecific associations, and recent deforestation is likely to have driven otherwise low-level hybridization to higher frequencies which may reduce the fitness of threatened populations. Y-chromosomal markers are especially informative because they provide working hypotheses for (1) the primary mechanism of hybridization (i.e., species A males × species B females) and, by extension; (2) the major direction of gene flow.