Population genomics of a predatory mammal reveals patterns of decline and impacts of exposure to toxic toads

Mammal declines across northern Australia are one of the major biodiversity loss events occurring globally. There has been no regional assessment of the implications of these species declines for genomic diversity. To address this, we conducted a species-wide assessment of genomic diversity in the northern quoll (Dasyurus hallucatus), an Endangered marsupial carnivore. We used next generation sequencing methods to genotype 10,191 single nucleotide polymorphisms (SNPs) in 352 individuals from across a 3220-km length of the continent, investigating patterns of population genomic structure and diversity, and identifying loci showing signals of putative selection. We found strong heterogeneity in the distribution of genomic diversity across the continent, characterized by (i) biogeographical barriers driving hierarchical population structure through long-term isolation, and (ii) severe reductions in diversity resulting from population declines, exacerbated by the spread of introduced toxic cane toads (Rhinella marina). These results warn of a large ongoing loss of genomic diversity and associated adaptive capacity as mammals decline across northern Australia. Encouragingly, populations of the northern quoll established on toad-free islands by translocations appear to have maintained most of the initial genomic diversity after 16 years. By mapping patterns of genomic diversity within and among populations, and investigating these patterns in the context of population declines, we can provide conservation managers with data critical to informed decision-making. This includes the identification of populations that are candidates for genetic management, the importance of remnant island and insurance/translocated populations for the conservation of genetic diversity, and the characterization of putative evolutionarily significant units

Genetic analysis of three remnant populations of the rufous hare-wallaby (Lagorchestes hirsutus) in arid Australia

The rufous hare-wallaby (Lagorchestes hirsutus) is now extinct in the wild on mainland Australia, but survives in captivity. However, endemic populations persist on Bernier and Dorre Islands, Western Australia. This study aimed to compare the genetic diversity and differentiation amongst three remaining rufous hare-wallaby populations using mitochondrial DNA (mtDNA) (cytochrome b, control region) sequence data and nuclear (microsatellite) markers. Levels of microsatellite diversity were low in both island populations but high in the captive mainland population. Levels of mtDNA diversity were low in all three populations. The mainland and island populations of L. hirsutus were found to be significantly differentiated for both microsatellite and mtDNA data, but the two island populations were significantly differentiated only for the microsatellite data. This pattern of differentiation is not consistent with the recognition of two separate island subspecies, but we recommend that the mainland and island populations be regarded as separate subspecies. The low diversity of the island populations and differentiation between island and mainland populations presents both challenges and opportunities for future management

Population structure of the brush-tailed rock-wallaby

1 page(s

Mapping the distribution of the telomeric sequence (T2AG3) in the red-necked pademelon, Thylogale thetis and the swamp wallaby, Wallabia bicolor

1 page(s

Phylogeographic structure within Phascogale (Marsupialia: Dasyuridae) based on partial cytochrome b sequence

The brush-tailed phascogale (Phascogale tapoatafa) is considered locally rare and vulnerable, despite being found in all mainland states of Australia. It is rarely detected in faunal surveys and the two most immediate conservation requirements are a determination of its current range and clarification of its taxonomic status. Measures of genetic differentiation amongst Phascogale tapoatafa populations in eastern, western and northern Australia were estimated using a partial (348 bp) sequence of mitochondrial DNA (cytochrome b gene). Observed sequence divergence within P. tapoatafa was substantial, with an average of 13% separating the allopatric populations in south-eastern, south-western and northern Australia. In comparison, an average of 16% sequence divergence separated the two currently recognised Phascogale species (P. tapoatafa and P. calura). Thus, Phascogale comprises four highly divergent lineages, suggesting that the genus is more diverse than previously thought. These data indicate that further taxonomic research is warranted

Revelations from a microsatellite DNA study of a curious anomaly amongst Thylogale stigmatica stigmatica and T. S. wilcoxi

1 page(s

First record of quadruplets in the Musky Rat-Kangaroo Hypsiprymnodon moschatus

3 page(s

Low levels of genetic diversity in island populations of the black-footed rock-wallaby, Petrogale lateralis

2 page(s