Determining genetic connectivity of bottlenose dolphin communities facilitates the identification of environmental and social factors that interact to shape dispersal in highly social marine mammals. Here, we examine the genetic structure and dispersal patterns among nine bottlenose dolphin (Tursiops aduncus) communities inhabiting different environment types (embayment and open coast) along the New South Wales coast from Eden to Byron Bay. Analysis of the mitochondrial DNA control region and seven microsatellite loci suggested the nine communities originated from a single ancestral population that progressively colonised the coast in a southward direction. Contemporary gene flow among communities, however, was predominately governed by habitat type. The two enclosed embayments (Port Stephens and Yamba) showed highest levels of genetic differentiation to dolphin communities ranging on the coast or in open embayments. Genetic differentiation among these coastal and open embayment communities generally followed a pattern of isolation by distance. Directional bias in recent migration rates was evident, with the centrally located Hunter communities consisting of individuals with mixed ancestry from the Northern NSW, Southern NSW and Port Stephens communities. Emigration from Port Stephens was substantially higher than in the opposite direction, indicating there may be social barriers to dispersal created by resident Port Stephens dolphins. Our results suggest that the scale of connectivity of bottlenose dolphins inhabiting heterogeneous environments is affected by local habitat adaptation. This has important implications to the management of communities exposed to increasing levels of anthropogenic disturbances, such as the intensive commercial dolphin-watching industry operating in Port Stephens
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