The koala, the only extant species of the marsupial family Phascolarctidae, is classified as 'vulnerable' due to habitat loss and widespread disease. We sequenced the koala genome, producing a complete and contiguous marsupial reference genome, including centromeres. We reveal that the koala's ability to detoxify eucalypt foliage may be due to expansions within a cytochrome P450 gene family, and its ability to smell, taste and moderate ingestion of plant secondary metabolites may be due to expansions in the vomeronasal and taste receptors. We characterized novel lactation proteins that protect young in the pouch and annotated immune genes important for response to chlamydial disease. Historical demography showed a substantial population crash coincident with the decline of Australian megafauna, while contemporary populations had biogeographic boundaries and increased inbreeding in populations affected by historic translocations. We identified genetically diverse populations that require habitat corridors and instituting of translocation programs to aid the koala's survival in the wild.

Fungi are a large, complex group, increasingly recognized as emerging threats. Their roles as modifiers of health mandate accurate portrayals of fungal communities in humans. As an entry point into the airways and gastrointestinal tract, fungi in the mouth are relevant to several biocompartments. We have revised current practices in sequence-based taxonomy assignments and employed the improvements to address the question of the fungal genera present in the healthy human mouth. The human oral mycobiome was surveyed using massively parallel, high throughput sequencing of internal transcribed spacer 1 (ITS1) amplicons from saliva following robust extraction methods. Taxonomy was assigned by comparison to a curated reference dataset, followed by filtering with an empirically determined BLAST E-value match statistic (10−42). Nomenclature corrections further refined results by conjoining redundant names for a single fungal genus. Following these curation steps, about two-thirds of the initially identified genera were eliminated. In comparison with the one similar metagenomic study and several earlier culture-based ones, our findings change the current conception of the oral mycobiome, especially with the discovery of the high prevalence and abundance of the genus Malassezia. Previously identified as an important pathogen of the skin, and recently reported as the predominant fungal genus at the nostril and backs of the head and ear, this is the first account of Malassezia in the human mouth. Findings from this study were in good agreement with others on the existence of many consensus members of the core mycobiome, and on unique patterns for individual subjects. This research offered a cautionary note about unconditional acceptance of lengthy lists of community members produced by automated assignments, provided a roadmap for enhancing the likely biological relevance of sequence-based fungal surveys, and built the foundation for understanding the role of fungi in health and disease of the oral cavity.

BackgroundWe present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development.ResultsThe genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements.ConclusionsAnalyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution.

The Tasmanian tiger or thylacine (Thylacinus cynocephalus) was the largest carnivorous Australian marsupial to survive into the modern era. Despite last sharing a common ancestor with the eutherian canids ~160 million years ago, their phenotypic resemblance is considered the most striking example of convergent evolution in mammals. The last known thylacine died in captivity in 1936 and many aspects of the evolutionary history of this unique marsupial apex predator remain unknown. Here we have sequenced the genome of a preserved thylacine pouch young specimen to clarify the phylogenetic position of the thylacine within the carnivorous marsupials, reconstruct its historical demography and examine the genetic basis of its convergence with canids. Retroposon insertion patterns placed the thylacine as the basal lineage in Dasyuromorphia and suggest incomplete lineage sorting in early dasyuromorphs. Demographic analysis indicated a long-term decline in genetic diversity starting well before the arrival of humans in Australia. In spite of their extraordinary phenotypic convergence, comparative genomic analyses demonstrated that amino acid homoplasies between the thylacine and canids are largely consistent with neutral evolution. Furthermore, the genes and pathways targeted by positive selection differ markedly between these species. Together, these findings support models of adaptive convergence driven primarily by cis-regulatory evolution.