Platypuses with their duckbills differ from other mammals as they lay eggs and produce venom, and researchers have sequenced the genomes of dozens of platypuses to give insight into their population history.
Researchers from the University of Oxford and the University of Sydney sequenced 57 platypuses from across their range in eastern Australia and Tasmania. As they report this week in Molecular Biology and Evolution, the researchers used those sequences to uncover strong population structure among the animals and note that about a half the platypuses had at least a third-degree relative among those sampled from the same river. Using a platypus family quartet, the researchers also estimated the de novo mutation rate among platypuses, finding it to be about average for mammals.
The researchers also traced back the last common ancestor of all platypuses to about 1 million years ago and found three deep branches on its phylogenetic tree. "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 [800,000 years ago]," the University of Sydney's Jaime Gongora says in a statement.