In addition, researchers found evidence of past population bottlenecks, particularly in North Queensland around 10,000 years ago, and identified modern populations (especially near the Carnarvon River) that would be aided by conservation efforts.
This could be consistent with it having evolved from the giant platypus species, O. "This finding does not necessarily contradict fossil evidence but suggests that the modern platypus extends back to the Early to Middle Pliocene. Donnelly commented: "Interestingly, the divergence times we have estimated predate the earliest fossil evidence for platypus." This implies that there has been extensive population structure in platypus samples across Australia over a long time period."ĭr. "The central Queensland samples likely shared an ancestral population with the North New South Wales samples about 300KYA. "We think it is most likely that there were three ancestral populations (Tasmania, North Queensland and North New South Wales/Central Queensland) which all coalesced around the same time, about 800KYA," said Dr. Jaime Gongora, from the University of Sydney, said the deepest branch on the population tree separated three separate groups: the samples from Tasmania (an island to the south of Australia that separated from the mainland around 12,000 years ago) those from north Queensland (in the far north) and the remaining samples, which are from central Queensland and New South Wales. "The relative ordering of the point estimates is consistent with the observation that mutation rates in mammals are negatively correlated with body mass and generation time," Dr.
They found it to be middle of the road for mammals, lower than humans and chimpanzees but higher than laboratory bred mice.
Hilary Martin, one of the lead authors of the study also from the University of Oxford said: "We estimated the de novo mutation rate in the platypus, the first estimate in a non-placental mammal." The research team was also able to estimate vital evolutionary forces at work including platypus mutation rates, divergence times, and population sizes throughout its history.ĭr. Additionally, there were 26 pairs of second- or third-degree relatives, in all cases from the same river or creek, or closely connected waterways, involving 28 of our 57 samples." "For example, we found that more than half of our samples had a least a third-degree relative amongst the other individuals sampled from the same river. "Our analyses provide insights into the population structure and levels of diversity in this species not previously possible and estimate the relatedness between individuals." "We have described the first population-scale, whole-genome sequencing study of the platypus," said Dr. They were able to establish a platypus family history and kinship in a level of detail not previously sampled.
The work was led by researchers at the Wellcome Centre for Human Genetics, University of Oxford and the Sydney School of Veterinary Science, University of Sydney, and published in the advanced online edition of Molecular Biology and Evolution. The platypus represents the earliest offshoot of the mammalian lineage, some 166 million years ago, from primitive ancestors that had features of both mammals and reptiles.Now, a greater effort to understand its ecological and population history has been made possible by the first, whole-scale genome sequencing efforts of 57 platypuses across Eastern Australia and Tasmania. “Comparing us with the platypus means that we can say something about our common ancestor, which was one of the earliest mammals, so that means that we can ask questions about what happened to make us mammals,” said Graves, after a briefing on the platypus genome, published in the journal Nature. “Its probably the most eagerly awaited genome since the chimp genome because platypuses are so weird,” said Jenny Graves, head the Comparative Genomics Group at the Australian National University. REUTERS/Mick TsikasĪ team of international scientists released the platypus genome on Thursday, saying its complex sequence would aid the study of human evolution - particularly the development of the immune, nervous and reproductive systems. An adult male platypus named Millsom is carried by his keeper at an animal sanctuary in Melbourne May 8, 2008.
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