Sarasota Dolphin Research Program

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Genetic analyses of social structure: Paternity and relatedness in Sarasota Bay
By Debbie Duffield, PhD, Portland State University

Petey (FB10), one of Sarasota’s most successful sires.

This project represents 25 years of genetic work on the Sarasota Bay bottlenose dolphin community. Over this time, we have brought a diverse array of genetic tools to the investigation of social structure in a well-known core population of dolphins. To date, we have developed DNA microsatellite panels from blood samples taken during capture-release efforts for 238 bottlenose dolphins of the Sarasota Bay community; 129 females and 109 males. Of the 238 dolphins sampled, 102 of these were calves born in the community to known mothers. Over the past two years we have also added 73 biopsy samples from dolphins sampled independent of the capture-release operations.

We are in the process of completing paternity exclusions for all the calves. Analyses have been completed for 71 of the calves and yield the following preliminary conclusions:

51 calves were sired by a male in the community.
Four males sired from 3-5 calves each; five males sired at least two calves each.
The most successful males were FB60, FB10, then FB46 and FB76.
20 calves (28%) were not sired by males in the community – as we have reported previously, the Sarasota Bay dolphin community is not a genetically isolated population.

We are currently engaged in finishing the paternity exclusions for the rest of the calves and completing the integration of the biopsy samples. In addition to helping us define the breeding structure of this community, these paternity assignments will allow us to correlate presence, behavior, morphology and health with breeding success.

To complete our understanding of the genetic and group structure of the Sarasota dolphin community, we are also particularly interested in defining the role of relatedness in observed social patterns. These data taken together with the paternity data will provide the basis for a comprehensive investigation of social unit structure in the Sarasota Bay dolphin community. In no other bottlenose dolphin community studied has it been possible to individually profile the entire community over five generations with both genetic analyses and long-term behavioral observations.