A first-of-its-kind census aimed at helping preserve the future of Australia's dolphin populations amid changes triggered by global warming has raised key conservation implications.
The study of Delphinus delphis along a 3000km stretch of the continent's southern coastline has found a need for greater efforts to preserve adaptive DNA diversity and connectivity.
Researchers say this will support long-term gene flow and evolutionary fitness during ongoing habitat changes, including oceanic conditions affected by climate change and human activity.
Flinders University biologist Andrea Barcelo says high levels of genomic variation can play an important part in the survival of common dolphins and other species.
"How the environment affects DNA diversity of marine populations can assist with their management and in forecasting how they may cope with climate change and other anthropogenic impacts," she said.
Flinders and Macquarie University scientists say maintaining the connectivity between pods can also promote future genomic variation.
"While so many breeding and feeding conditions are still unknown, it's important for managers of our coastal environments to consider the importance of DNA diversity," said study co-author Professor Luciana Moller.
"This is particularly so in the event of changes in key environmental conditions such as water temperatures, salinity and food sources."
The adaptive divergence from more than 200 dolphins studied showed five populations from Western Australia to Victoria and compared this with the key environmental conditions and available fish food supplies fuelled by oceanic upwellings and seasonal circulations.
Genomic variation in dolphins off the southern WA coast was associated with local currents, while those from continental shelf break sites were impacted by fluctuations of primary productivity and sea surface temperatures.
In contrast, genomic differentiation among pods from protected coastal habitats and more enclosed embayment areas was mainly linked to fluctuations in salinity and local environment temperatures.
The different seascape assessments identified candidate genes for future comparative studies of common dolphins and potentially other delphinid species that share similar dynamic environments around the world.