Genetic diversity essential for the survival of the Western Swamp Tortoise, our most endangered reptile

Posted on Posted in scaly, Western Austraila

Melanie shares another project supported by the Foundation for National Parks and Wildlife; research into the genetics of Australia’s most endangered reptile.

The Western Swamp Tortoise is Australia’s most endangered reptile. It has an ancestry that dates back 15-20 million years, but for 113 years this tortoise was thought to be extinct. It was only rediscovered in 1953 by chance.

This tiny tortoise only grows up to around 15 cm in length. It needs a special type of swamp with a clay, or clay and sand, bottom that only fills with water for a short time every year. This environment affects the Western Swamp Tortoise’s colouring, as does its age. They are yellow-brown or black on top, and black, yellow or cream underneath.

Western Swamp Tortoises can live for over 60 years and still have young. In November to early December they can lay 3-5 hard shelled eggs in a shallow underground nest, which hatch the following winter.

The Western Swamp Tortoise (Photo by G. Kuchling, IUCN Web)

In 2003, there were only two populations of Western Swamp Tortoises left in the wild, in the Swan Valley near Perth in Western Australia. Twin Swamps and Ellen Brook Nature Reserves are important sites for this species. The Western Swamp Tortoise could not survive without these ephemeral swamps. This tortoise has always had a restricted range, but its numbers have greatly declined as threats have increased.

Much of the Western Swamp Tortoises’ habitat has been cleared, modified or destroyed, and the wetlands where they live have not been filling up as much as they need. Foxes, cats, rats and wildfires have also killed many tortoises. Native animals such as crows, goannas and birds of prey also eat tortoises if they can find them.

As numbers of Western Swamp Tortoises declined in the wild, scientists began a captive breeding program to save this species. Around 20 years ago only 50 Western Swamp Tortoises were left, but thanks to the captive breeding program around 700 are alive today.

The Foundation for National Parks & Wildlife is helping to protect the Western Swamp Tortoise before it is too late.

In 2012 the Foundation is providing funding to PhD candidate Ms Danielle Giustiniano of the School of Animal Biology, University of Western Australia to conduct crucial research that will help conserve the Western Swamp Tortoise.

Ms Giustiniano is investigating the use of genetic markers to better manage the current captive breeding program of the Western Swamp Tortoise, run by Perth Zoo.

Due to the small number of founding tortoises who helped rebuild population numbers, inbreeding could become a real threat to the survival of this species. Appropriate management of genetic diversity is needed to ensure their survival in captive bred and wild populations.

Ms Giustiniano’s research will allow analysis of individual Western Swamp Tortoise genetics. This will also allow for the construction of an accurate studbook. DNA profiling of the Western Swamp Tortoise will also help determine the success of the current Perth Zoo practices to maintain genetic diversity in their captive breeding program for this species.

Western Swamp Tortoise management practices may be modified based on Ms Giustiniano’s findings to ensure that genetic diversity is maintained, inbreeding minimised, and a brighter future is secured for this species.

Find out more about Ms Giustiniano’s research here.

You can also get involved in release/volunteer work to help the Western Swamp Tortoise – click here to find out how at the Friends of the Western Swamp Tortoise site.

Find out more about the Perth Zoo Western Swamp Tortoise captive breeding program here.

Find out more about the Foundation for National Parks & Wildlife here.

Leave a Reply

Your email address will not be published. Required fields are marked *