Death, Disease, and DNA Down Under: exploring the genetic interplay of marsupials and their diseases

Abstract

Wildlife diseases present a major threat to biodiversity, often worsened by climate change, habitat loss, and genetic bottlenecks, leading to species declines and ecosystem disruption. Marsupials face two major diseases: chlamydiosis in koalas, causing blindness and infertility, and devil facial tumour disease (DFTD), a contagious cancer that has reduced Tasmanian devil populations by up to 80%. Other dasyurids, like quolls and kowaris, also show high cancer susceptibility. Genomics now enables detailed immunogenetic studies, moving beyond microsatellites to whole-genome analyses. Using multi-omics data, this research explores immunogenetic diversity at three scales: across marsupial species, within species, and within disease. Comparative genomics revealed rapid expansions of Ras oncogenes in dasyurids and bandicoots, likely linked to reproductive biology and cancer risk. In koalas, analysis of 418 genomes uncovered antimicrobial peptide diversity, including CNVs of PhciCATH5, potentially driven by chlamydia pressure. For DFTD, transcriptomes from four genotypic clades showed similar expression profiles, suggesting a single therapeutic approach could be broadly effective. Overall, this work demonstrates how genomic tools illuminate host–disease interactions, informing conservation and management strategies for threatened marsupials.