Sea star population genetics

12 March, 2010

Biscuit star
One of Kate's study species, the biscuit star Tosia neossia.
Image: Julian Finn
Source: Museum Victoria

Museum PhD student Kate Naughton is halfway through a major project to map the genetic diversity of sea stars, or starfish, over the southern Australian coast. Her fieldwork samples selected populations of widespread, shallow-water sea stars from New South Wales to Western Australia, looking for clues about their distribution during glacial periods.

“What I’m looking for are areas where we find really high genetic diversity within a species, and which areas are more similar or ‘monomorphic’,” said Kate. “The idea is that sites with high diversity might be glacial refuges – places that a population contracts to when the climate is unfavourable and they can’t go anywhere else.”

Kate’s study is ambitious not only because it covers such a massive coastline, but because it involves a number of scientific disciplines, including ecology, taxonomy (the classification of species), geology, and genetics. Furthermore, she’s finding that defining a species is not always straightforward. Among the biscuit stars she studies, she has found species that hybridise, species that look the same but are genetically quite distinct, and species that look completely different but their genes tell her they belong to the same group. Western Australian populations have been particularly interesting in this respect. From preliminary data, she noted that “Albany looks a bit weird!”

Kate’s PhD is co-supervised by MV marine scientist Dr Tim O’Hara and University of Melbourne geneticist Dr Belinda Appleton which helps with the multidisciplinary nature of her research. A recent diving trip with Tim and another museum staffer, Dr Julian Finn, brought back some photographs of vibrantly-coloured biscuit stars. “It’s incredibly useful to photograph these animals when you’re looking at morphological differences, because they lose their colour when preserved in alcohol.”

Ultimately, knowing more about how sea star populations have expanded and contracted in the past will help predict what will happen with climate change in the future. Another useful application may be better management of marine national parks. “It would be a very useful resource,” explained Kate. “In the long term, it makes sense to protect ‘source’ populations rather than ‘sink’ populations.”

Comments (3)

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Natasha Frisch 15 March, 2010 09:35
Beautiful images.
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Kate 15 March, 2010 12:51

Thanks for your comment, Natasha - Julian Finn is the photographer. More of his pictures are featured here.

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Patti Bond 3 February, 2012 09:31
ive never heard of a biscuit sea star. It is beautiful! Thank you for posting.
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