Examination of genetic structure in wild populations of Morelet's crocodile (Crocodylus moreletii) in Belize, Central America
Dever, Jennifer A.
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Biologists agree that both environmental and genetic factors contribute to species survival (Haig 1998; Partridge and Bmford 1994). Previous work has demonstrated the significance of short-term demographic and environmental threats to populations, as well as the important role of genetic diversity in species viability (Mace et al. 1996). Determining the genetic structure of populations of endangered species is a way to optimize conservation programs (Saltonstall et al. 1998; Avise 1996; Moritz 1994). Little is known about the biology of Morelet's crocodile, a freshwater species found in the lowlands of Central America. As a top predator, this species plays a vital role in the marshland ecosystem. In this project, I have investigated the genetics of several wild populations of Morelet's crocodiles in Belize. Microsatellites, tandemly repeated segments of DNA, were accessed using primers developed for other Crocodylus species. Nine polymorphic microsatellite loci were examined to determine the genetic structure of populations, as well as estimate the mode of gene flow exhibited in this taxa. Analysis of molecular variance, average heterozygosities, Nm and genetic subdivision estimates (FST, RsT and d\i ), suggest frequent movement of individuals between populations. The data are consistent in supporting an isolation by distance and island model of gene flow. Furthermore, I found two contiguous populations to be an important source of variation for outlying smaller populations. This study is part of a broad body of continuing work that will help build the foundation for future conservation programs involving Morelet's crocodiles.