The mysterious marsupial

The southern marsupial mole (Notoryctes typhlops), also known as the itjaritjari or itjari-itjari, is a mole-like marsupial found in the western central deserts of Australia. It spends the majority of its life tunneling beneath Australia’s vast red deserts. Survival in this unforgiving habitat requires a whole array of specialized traits. For example, the marsupial mole has vestigial eyes that lack both a lens and a pupil hidden beneath delicate, round eyelids with fused lids. To find their way in the perpetual darkness, the mysterious marsupials instead rely on a keen sense of smell and acute hearing.

Southern marsupial mole (Notoryctes typhlops) Photo Credits & acknowledgements – Photograph by Mike Gillam ©2019 California Academy of Sciences

A number of other adaptations like fused neck vertebrae with bulldozer-like rigidity, bony armor protecting the snout and Lobster-like claws on the forelimbs make this ground dweller a powerful digging machine. When doing what it does best, this energetic digger virtually swims through the sand in search of ants and juicy beetle larvae.


Like so many Australian mammals, female marsupial moles have a pouch in which their young complete their development. Interestingly the mole’s pouch opens toward the back, an adaptation that protects young moles from being inundated with sand as the mother burrows.


Despite the physical similarities between marsupial moles and true moles, the two lineages are only very distantly related, having likely diverged during the Mesozoic Era (~160 million years ago). Further, molecular data suggests that Notoryctemorphia separated from other marsupials around 64 million years ago (1). The resemblance between true and marsupial moles is a classic example of convergent evolution, a process by which two distantly related species, or groups, evolve similar traits in response to a similar set of environmental conditions.


DNA Zoo has been working with Prof. Andrew Pask and Dr. Stephen Frankenberg from the University of Melbourne, Australia to develop genomic resources for the species. We combined 3,530,386 Nanopore reads (~9x coverage) provided by the Pask lab, University of Melbourne with 239,676,293 PE Illumina WGS reads and 681,381,650 PE Hi-C reads generated by the DNA Zoo labs to generate a chromosome-length assembly, shared today! The genome was generated using wtdbg2, 3D-DNA (Dudchenko et al., 2017) and Juicebox Assembly Tools (Dudchenko et al., 2018). See our Methods page for more details!


This effort has been supported by Oz Mammals Genomics initiative, a Bioplatforms Australia framework initiative, building genomic resources for conservation through a thorough understanding of the evolution of Australia’s unique mammals that are now under threat, through climate, disease or habitat modifications.


The Hi-C work was supported by resources provided by DNA Zoo Australia, The University of Western Australia (UWA) and DNA Zoo, Aiden Lab at Baylor College of Medicine (BCM) with additional computational resources and support from the Pawsey Supercomputing Centre with funding from the Australian Government, the Government of Western Australia. The team thanks Zhenzhen Yang from ShanghaiTech, DNA Zoo China, for her help with the contigging of this genome assembly.


Check out the interactive contact map of the southern marsupial mole-rat below, and don't forget to visit the assembly page for more information.


Citations

1. Kirsch, J,A.W.; Springer, Mark S.; Lapointe, François-Joseph (1997). "DNA-hybridization studies of marsupials and their implications for metatherian classification". Australian Journal of Zoology. 45 (3): 211–80. doi:10.1071/ZO96030.

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