Flinders University researchers undertake world’s first major dolphin DNA study

In his novel So Long, and Thanks for All the Fish, the late great Douglas Adams wrote: “Man has always assumed that he is more intelligent than dolphins because he has achieved so much – the wheel, New York, wars and so on – while all the dolphins had ever done was muck about in the water having a good time.

“But, conversely, the dolphins had always believed that they were far more intelligent than man – for precisely the same reasons.”

I appreciate the Hitchhiker’s Guide to the Galaxy author’s point. But when dolphins start sequencing the human genome, I’ll start taking the squeaky clowns seriously.

That’s because, Mr Adams, Australian scientists of this species have undertaken the first widespread census of the genetic diversity of the common dolphin (Delphinus delphis). The researchers gathered information on the genetic variety of dolphin populations living along 3000km of Australia’s southern coastline.

Read more: How will Arctic mammals respond to climate change?

The comprehensive study coming out of Adelaide’s Flinders University has raised key issues for future conservation efforts. It calls for a more determined endeavour to preserve diversity and assist connectivity between the dolphin groups living in these waters.

Published in BMC Ecology and Evolution journal, the researchers say such efforts will support long-term gene flow and adaptation during habitat changes, such as those triggered by human activity including climate change.

High levels of genomic variation play an important role in the survival of species, including marine mammals which inhabit vast ranges.

“Information about how the environment affects DNA diversity of marine populations can assist with the population management, and in forecasting how they may cope with climate change and other anthropogenic impacts,” says lead author and Flinders University researcher Dr Andrea Barceló.

A key to preserving genomic variation, which is critical to helping populations survive through habitat changes like those due to climate change, is maintaining connectivity between disparate groups of the same species.

“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, particularly in the event of changes in key environmental conditions such as water temperatures, salinity, and food sources,” adds co-author Luciana Möller, an associate professor in marine biology at Flinders.

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The major DNA study looked at the genetics of more than 200 individuals. The data showed five different dolphin populations from the study’s western-most boundary off the coast of Western Australia, to the eastern edge off Victoria’s shore.

This information was compared with key environmental conditions and the relative availability of food. The common dolphin’s food source, fish, is dependent on oceanic upwellings and local seasonal circulations.

In Western Australia’s southern waters, genomic variation among the dolphins was associated with local currents. Further south where the oceanic tectonic plate ends, leading to a continental shelf break where the ocean depth suddenly drops, variation in dolphin genes was affected by fluctuations in levels of photosynthesis in energy production among microorganisms and sea surface temperatures.

In contrast, the variety in dolphins in protected coastal habitats and enclosed bay areas was affected by salinity and local temperatures.

The team believes the genomic assessments of the seascape has identified genes that can be used for future comparative studies, not only of the common dolphin but other dolphin species around the world. Putting our intellectual rivalry to one side, the genetic research shows the way forward for the preservation of these remarkable creatures.

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