Scientists have sequenced the genome of the critically endangered southern corroboree frog \u2013 one of Australia\u2019s most threatened amphibians \u2013 in hope that the information could be used to aid its recovery.<\/p>\n
The striking alpine frog, which has distinctive yellow and black markings, is so threatened by disease and the drying of its habitat due to climate change, that it is considered \u201cfunctionally extinct\u201d. The species survives in the temporary pools and peat bogs of Kosciuszko national park in New South Wales, with the help of zoo breeding and re-introduction programs.<\/p>\n
\u201cThey\u2019re quite unique frogs. They belong to this ancient family of frogs that\u2019s only found in Australia,\u201d said conservation biologist Dr Tiffany Kosch from the University of Melbourne and lead author of the paper published in Wellcome Open Research.<\/p>\n
\u201cThey\u2019re about 100m years old.\u201d<\/p>\n
The frog\u2019s genome was equally remarkable. Despite their tiny size, the researchers found their genome was enormous \u2013 three times the size of a human\u2019s \u2013 and one of the largest for a frog.<\/p>\n
\u201cA lot of other frogs in their family have much smaller genomes \u2013 including one of the smallest frog genomes on record,\u201d Kosch said, suggesting it indicated something unusual in their evolutionary history.<\/p>\n
Their genome was also \u201cfull of non-coding DNA\u201d \u2013 genetic material that doesn\u2019t directly code for proteins \u2013 and repeated elements, she said. \u201cWe\u2019re still exploring what this might mean for the species, and for other amphibians.\u201d<\/p>\n
Mapping the genome took 10 years of work. Frog tissue collected in Australia had to be transported to New York at temperatures of -80C. Once there, the DNA was extracted and chopped up into \u201ctiny puzzle pieces\u201d, Kosch said, which were analysed and re-assembled by co-authors at the Vertebrate Genome Laboratory.<\/p>\n
Kosch has since embarked on new research \u2013 made possible by the genome \u2013 which aims to explore and understand the species\u2019 susceptibility to the chytrid fungus disease.<\/p>\n
\u201cWe are trialling methods such as selective breeding and genetic engineering of the frogs to hopefully increase their resistance. So that\u2019s going to be our work for the next five to 10 years,\u201d she said.<\/p>\n
\u201cThe hope is that work with the southern corroboree frog could be used as a proof-of-concept for other frogs threatened by the chytrid fungus, and potentially other species threatened by climate change. The genome is really just the first step in helping us get there.\u201d<\/p>\n
Dr Simon Clulow, an associate professor in conservation ecology at the University of Canberra who was not involved with the research, said having the full genome sequence made it easier to ask and answer questions about a species.<\/p>\n
\u201cThe main impact on corroboree frogs, as with many frogs around the world, which are now the most threatened vertebrate class on Earth, is an invasive disease called chytrid fungus,\u201d Clulow said.<\/p>\n
One potential avenue for helping the species overcome the disease was identifying resistant genetic traits, he said, and mapping the genome was \u201ca really useful step towards this sort of goal\u201d.<\/p>\n
Frog genome research was in its early development, said Prof Nicki Mitchell from the University of Western Australia, a zoologist and Biodiversity Council Member who was not involved with the research.<\/p>\n
\u201cFor various reasons, frogs have been one of the slowest groups in the vertebrate world to have genomes completed,\u201d she said.<\/p>\n
This was partly because frog genomes were relatively larger than other vertebrates and because some species carried \u201cextra genetic baggage\u201d, such as double-copies of chromosomes.<\/p>\n
The southern corroboree frog was probably the highest priority for an Australian frog genome, Mitchell said, given it was \u201cour most high profile amphibian on the precipice of extinction\u201d.<\/p>\n
While the frog was among 110 priority species identified and supported under the government\u2019s Threatened Species Action Plan, there were about 2,200 listed as threatened under the Environment Protection and Biodiversity Conservation Act.<\/p>\n
The funding for biodiversity was \u201cminuscule compared to what we need\u201d, Mitchell said. The Biodiversity Council has called for an increase in nature spending, equivalent to at least 1% of the federal budget.<\/p>\n
\u201cThe species, in some ways, is a symbol of the twin crises that we\u2019re facing as a globe, of climate change and biodiversity loss.\u201d<\/p>\n