Using Genetics to Examine Population Structure of Bottlenose Dolphins along the Central West Coast of Florida
By Anna Sellas, M.Sc.,
University of California, Santa Cruz

With the official completion of my thesis research in May 2002, many interesting facts have been revealed regarding the population structure of bottlenose dolphins in the inshore and coastal waters near Sarasota Bay. Using mitochondrial DNA and nuclear microsatellite markers, significant population differentiation was detected between the Sarasota Bay residents and bottlenose dolphins sampled in the nearshore coastal Gulf waters. This result is surprising given the short geographical distance between these areas and the lack of obvious geographic barriers to prevent gene flow. Analyses were also run for males and females separately and these results revealed a significant amount of male-biased dispersal between the coastal Gulf and Sarasota Bay. This latter result further supports previous findings based on photo-identification documenting resident males of Sarasota Bay having wider ranging patterns and more frequent interactions with dolphins of neighboring areas than resident females. In November of 2001, this research was presented at the 14th Biennial Conference on the Biology of Marine Mammals held in Vancouver B.C. In addition, these results are currently being prepared for journal publication.

In an effort to expand our understanding of the population structure of bottlenose dolphins along the central west coast of Florida, we collected over 50 biopsy samples in both Charlotte Harbor and Tampa Bay, FL, during field sessions conducted in both 2001 and 2002. We are now able to compare the genetic data that we have collected from these Tampa Bay and Charlotte Harbor samples with the data from Sarasota Bay and the coastal Gulf of Mexico. Comparative analyses of population differentiation and genetic diversity are currently underway for all four of these areas and these results should aid conservation managers in their decisions regarding stock delineation and management. Funding for this research was provided by the Florida Fish and Wildlife Conservation Commission, Chicago Zoological Society, Mote Marine Laboratory, Harbor Branch OI Protect Wild Dolphins Program, NOAA Fisheries. All molecular analyses were conducted at the NMFS SEFSC Marine Mammal Molecular Genetics Laboratory under the leadership of Dr. Patricia Rosel.