Abstract

The West Indian manatee consists of two subspecies, the Florida manatee, Trichechus manatus latirostris, and the Antillean manatee, T. manatus manatus, which includes the Puerto Rico population.^1,2,3 Genetic investigations allow comparisons within and between the two populations. Previous mitochondrial DNA studies identified three haplotypes in Puerto Rico (A, A2, and B) and one haplotype in Florida (A).^4,8 Mitochondrial DNA analysis detects historical population structure, hybridization, and migration rates. Therefore, although the two populations share a haplotype, these mitochondrial DNA data are insufficient for fine-scale contemporary manatee population assessment.

To evaluate the Florida manatee population structure, nuclear DNA (microsatellite) studies have been implemented. Recent microsatellite investigations demonstrate little genetic differentiation within the Florida population.⁶ Similar microsatellite analyses of the Puerto Rico population are being used to validate the markers and address the amount of migration and relatedness between the populations.

The preliminary analysis presented here examined fifteen polymorphic nuclear DNA microsatellite loci^5,6 in Florida and Puerto Rico manatees. A Bayesian cluster analysis was performed using the program STRUCTURE 2.1⁷ to identify putative ancestral source populations for extant manatees. The analysis calculated the likelihood of individuals belonging to a population, assuming some admixture (i.e., genetic isolation was not assumed). The resultant proportion of each Florida individual having ancestry in Florida was 0.967 and each Puerto Rico individual having ancestry in Puerto Rico was 0.977. These preliminarily results suggest that the Florida and Puerto Rico manatees represent distinct populations.

Acknowledgments

Funding for this project was provided by the University of Florida College of Veterinary Medicine and the USGS. Work for this project was covered under U.S. Fish and Wildlife Service wildlife research permit MA791721-4 issued to the USGS Sirenia Project and under a letter of authorization from Puerto Rico's Department of Natural and Environmental Resources; IACUC approval was granted by UF.

References

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