Sea snake at risk of being lost in hybrid swarm

Feb 17, 2014 by Robyn Mills

A University of Adelaide-led project has found that the endangered dusky sea snake is even more at risk of extinction than thought because of surprising cross-species hybridisation.

This follows a pattern of unexplained drastically declining populations of sea snakes in the reefs of the Timor Sea in north-west Australia over the past 15 years.

Published in the journal Biological Conservation, the study found that at one of only two remaining coral reefs where they are still found, dusky sea snakes had hybridised almost completely with the closely related olive .

"Genetically-pure duskies might now only be found at one remaining reef ̶ the isolated Scott Reef, an area of about 160 square kilometres in the Timor Sea, about 300km north of the Kimberley coast," says project leader and lead author Dr Kate Sanders. "Such loss of biodiversity because of hybridisation is an important conservation problem and there are dire implications for the conservation status of the dusky sea snake."

Referred to as the "miners' canary" of coral reef health, sea snakes bear live young rather than eggs and are the only fully aquatic reptile.

The sea snakes are Australian native animals. They evolved in Australia from a land snake ancestor and have been highly successful in adapting to a marine environment. There are 62 species, found mostly in Australia and South-East Asia with the greatest diversity previously on the isolated reefs of the Timor Sea.

"Five Timor Sea reefs previously supported the highest diversity and abundance of sea snakes in the world, but the largest reef, Ashmore, has lost all of its nine resident species over the past 15 years," says Dr Sanders.

In this study the researchers collected and released sea snakes on the remaining four reefs by snorkelling with nets. They used DNA fingerprinting to show that endangered dusky sea snakes frequently interbreed with closely related olive sea snakes which are much more locally abundant and wide ranging.

"These reefs are largely undisturbed by fishing and habitats have remained intact so we had assumed the populations would have been stable," Dr Sanders says. "But when we surveyed at Hibernia Reef, we were very surprised to find interbreeding at that level, with the two species almost completely hybridised to produce a so-called 'hybrid swarm'.

"Hibernia is one of only two reefs that have supported dusky sea snakes following their extinction at Ashmore Reef. Now it seems that they are on the path of genetic extinction at Hibernia too. Olive and dusky sea snakes diverged about 500,000 years ago. The loss of biodiversity through this 'reverse speciation' is of particular concern because we don't know what has driven this change on our reefs. It certainly requires close monitoring and further investigation."

Explore further: Studying sea snakes for underwater robot design

More information: Kate L. Sanders, Arne R. Rasmussen, Michael L. Guinea, High rates of hybridisation reveal fragile reproductive barriers between endangered Australian sea snakes, Biological Conservation, Volume 171, March 2014, Pages 200-208, ISSN 0006-3207, dx.doi.org/10.1016/j.biocon.2014.01.013.

add to favorites email to friend print save as pdf

Related Stories

Studying sea snakes for underwater robot design

Feb 03, 2014

The fascinating body structures of sea snakes which adapt them for life in water are being studied by University of Adelaide researchers as inspiration for a marine robot - the first of its kind.

New snake species found in a museum

Oct 25, 2012

Scandinavian scientists have discovered a new species of snake in a Copenhagen museum, which they have called the Mosaic sea snake, a Swedish university said on Thursday.

Deadly sea snake has a doppelganger

Nov 19, 2012

(Phys.org)—Scientists have discovered that the lethal beaked sea snake is actually two species with separate evolutions, which resulted in identical snakes.

Tracking the deep sea paths of tiger sharks

Jan 08, 2014

Shark research scientist, Dr Jonathan Werry, has undertaken a four year study tracking the migratory patterns of tiger sharks (Galeocerdo cuvier) across the Southwest Pacific.

Recommended for you

Meteorite that doomed dinosaurs remade forests

11 hours ago

The meteorite impact that spelled doom for the dinosaurs 66 million years ago decimated the evergreens among the flowering plants to a much greater extent than their deciduous peers, according to a study ...

New camera sheds light on mate choice of swordtail fish

13 hours ago

We have all seen a peacock show its extravagant, colorful tail feathers in courtship of a peahen. Now, a group of researchers have used a special camera developed by an engineer at Washington University in ...

App helps homeowners identify spiders

16 hours ago

Each autumn the number of spiders seen indoors suddenly increases as males go on the hunt for a mate. The Society of Biology is launching a new app to help the public learn more about the spiders that will ...

User comments : 0