If the date is January 22nd and you happen to be a tammar wallaby, the chances are high that it will be your birthday – as well as the anniversary of your conception. In between these two events, you will have spent eleven months in suspended animation, followed by a short one month gestation (in which you only grew to the size of a kidney bean).
These quirks of tammar reproduction are just some of the many fascinating biological features whose underlying genetics may now be explained, thanks to the publication in Genome Biology of the tammar wallaby genome and transcriptome sequences.
The article, which is accompanied by a number of companion articles in BMC Genomics, BMC Molecular Biology, BMC Immunology, BMC Genetics, BMC Developmental Biology, BMC Evolutionary Biology and EvoDevo (with a Research Highilight in Genome Biology thrown in for good measure), represents the first kangaroo, second Australian marsupial and third marsupial published genome sequence.
Australian marsupial phylogeny (millions of years)
The tammar wallaby is well chosen as the subject of a genome sequencing project, as it is a model marsupial organism studied for insights into immunity, development and reproduction that may have parallels in human health. Its location in the mammalian phylogeny also renders it an invaluable organism for comparative genomics, affording scientists the luxury of asking the important human interest questions exploring what separates the evolutionary trail leading to Homo sapiens from those leading to other mammals.
The first kangaroo genome is a landmark in Australian science, and so it is fitting that the international consortium responsible for its sequencing has Australian researchers at its head. One of the project leaders, Marilyn Renfree (The University of Melbourne), summarizes the Genome Biology article as providing scientists "with many possibilities for understanding how marsupials are so different to us." She also underscores the potential of translating tammar strategies for survival to the treatment of human disease.
When reading BioMed Central's tammar wallaby genome and transcriptome article series, gems to look out for include innovations in the immune system, and a sex chromosome system likely to be more akin to that of the ancestral mammal than is the eutherian XY pair. Another highlight is the finding that the tammar's two thymuses do not have distinct transcriptomes. There may be many more yet to be discovered clues in the sequences and, as all datasets have been made publicly available, the kangaroo genome’s secrets are now ripe for the picking.
Kangaroo Island, South Australia: home to the individual tammar whose genome was sequenced