| Summary: | This study was designed to examine the social and genetic structure of bottlenose dolphins inhabiting the coastal waters near Jacksonville, Florida. Behavioral and photo-identification data obtained from December 1994--December 1997 identified three behaviorally differentiated bottlenose dolphin communities in the coastal and inshore waters of the Jacksonville study area: Northern, Southern and Coastal. These parapatric communities differed in density, habitat fidelity, and social affiliation patterns. Although some dolphins were photographed outside of their community's range, interactions between communities were observed infrequently. The Northern community was the most isolated of the three, with 96% of sightings (n = 353 of 366 sightings) containing only dolphins that had been photographed within the community's range. Seventy-eight percent (n = 145 of 185 sightings) of the groups photographed in the Southern community's range contained only Southern community members. The Coastal community was the least isolated, 48% (n = 38 of 79 sightings) of the groups photographed in the Coast region contained dolphins photographed at least once the inshore habitat. Despite the fact that bottlenose dolphins have the ability to travel great distances and no geographic barriers to dolphin movements between communities exist within the Jacksonville study area there was significant genetic structure of both mtDNA haplotypes (FST = 0.49, P ≤ 0.001) and nuclear microsatellite loci (FST = 0.031, P ≤ 0.001). Although the three Jacksonville communities use contiguous habitats, the Northern community was behaviorally and genetically differentiated from the Southern and Coastal communities. Evidence for genetic structure on such a small geographic scale relative to the entire northwest Atlantic range of bottlenose dolphins strongly indicate that management and conservation efforts be based on a finer scale than is currently being considered.
|
|---|