Monika R, PSG College of Technology, Coimbatore
Australia has the highest recorded rate of species extinction in the world. During the European colonization in 1788, 34 terrestrial species were declared to be extinct. (i.e.) Since European colonization, native rodents have been the most severely tormented by these recent extinctions, contributing around 41% of Australian mammal extinctions.
The scale and timing of their decline are largely unresolved. But recently a study was conducted by researchers at the Australian National University to determine the scale and timing of their decline. They used museum specimens to come up with genome-scale data from eight extinct Australian rodents and their 42 living relatives.
The researchers also taxonomically resurrected a species from extinction called Gould’s mouse- a species thought to be extinct 150 years ago. The species still survive as an island population in Shark Bay, Western Australia- an ecological wonderland and a UNESCO world heritage site.
The mouse has been around this whole time, surviving in several islands in Western Australia, according to a study published this month in PNAS.
Gould’s mouse still exists!
Emily Roycroft, lead author of the study and postdoctoral fellow at the Australian National University said, “We compared the DNA of Gould’s mouse, thought to be extinct, to any or all living species of native rodents. What we found was that it absolutely was genetically indistinguishable from another living species, the Shark Bay mouse”. She also added that initially, they thought the Gould’s mouse only lived in New South Wales and Victoria, but after the results of their study, it’s clear that it once roamed across most of the Australian mainland.
Determining the scale and timing of the decline
By understanding and determining the genetic diversity of a population, ecologists can measure to what extent the arrival of Europeans contributed to their extinction. So, Roycroft together with other researchers began to determine the level of genetic diversity present before they became extinct by examining the relationships between extinct Australian rodents and living species. To do this, they extracted DNA from 87 museum specimens and mapped out the gnawing mammalians’ genomes.
European colonization and species extinction
When ecologists observed the genomic sequence of Aussie animals: the fully-extinct Thylacine and also the endangered Tasmanian devil, which is now extinct on mainland Australia, they came up with a theory that Australian rodents were already experiencing a decline because of loss of genetic diversity and European colonization didn’t cause their extinction, but only accelerated it.
However, the study also found that this wasn’t the case for rodent extinction. There was no evidence for reduced genetic diversity in the extinct species before the late 19th or 20th century, which indicates that their populations were previously large and began to decline after the European colonization of Australia. Their fast decline following European colonization suggests genetic diversity doesn’t necessarily protect species from catastrophic extinction. “This shows how severe the impacts of European colonization are,” Roycroft added.
Additionally, comparative analyses suggested that extinction risk was elevated for larger-bodied rodents and varied among biomes, with larger species more likely to go extinct. Their results highlight the capacity of collections-based research to inform conservation and management of persisting species.
Conservation of surviving species
With unprecedented sampling across radiation of extinct and living species, they have unlocked a previously inaccessible historical perspective on extinction in Australia. Similarly, future genome sequencing projects may uncover other living species once thought to have vanished from the planet. Except, for now, we at least know the Gould’s mouse continues to be surviving around Shark Bay.
The continuous loss of native rodents from the Australian landscape has the potential to cause broader ecosystem collapse. Because, the native rodents are important ecosystem engineers (i.e.) they play an integral role in Australian environments as consumers of plants, fungi, and invertebrates, and as a prey source for other native species.
Their study stands as an example to learn about species that have become extinct using data from museum specimens. Similarly, we will learn more about the broader pattern and pace of extinction of most of Australia’s native species, if these sorts of data are accessed. Thus, understanding the genome of extinct species can help inform conservation efforts for surviving species.
Also read: Clofoctol: A potential Antibiotic against SARS-CoV-2
Source:
- “Extinct” Australian mouse discovered alive. (2021, July 5). Popular Science. https://www.popsci.com/animals/australian-extinct-mouse-discovered-alive/
- Roycroft, E., MacDonald, A. J., Moritz, C., Moussalli, A., Portela Miguez, R., & Rowe, K. C. (2021). Museum genomics reveals the rapid decline and extinction of Australian rodents since European settlement. Proceedings of the National Academy of Sciences, 118(27), e2021390118. https://doi.org/10.1073/pnas.2021390118
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About the author: Monika Raman is an undergraduate student pursuing her final year B. Tech in Biotechnology. She is an enthusiastic Biotech student aspiring for an opportunity to develop skills and grow professionally in the research field. Extremely motivated and possess strong interpersonal skills.
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