Local adaptation of Dromiciops marsupials (Microbiotheriidae) from southern South America: Implications for species management facing climate change

The two species of the microbiotheriid marsupial genus Dromiciops (Dromiciops bozinovici: “Panchos's monito del monte” and Dromiciops gliroides: “monito del monte”) exhibit a marked latitudinal genetic differentiation. Nevertheless, it is unclear whether this differentiation results from neutral processes or can be explained, to some extent, by local adaptation to different environmental conditions. Here, we used an SNP panel gathered by Rad-seq and searched for footprints of local adaptation (putative loci under selection) by exploring genetic associations with environmental variables in the two species of Dromiciops in Chilean and Argentinean populations. We applied three methods for detecting outlier SNPs and two genotype–environment associations approaches to quantify associations between allelic frequencies and environmental variables. Both species display strong genetic structure. D. bozinovici exhibited three distinct genetic groups, marking the first report of such structuring in this species using SNPs. In contrast, D. gliroides displayed four genetic clusters, consistent with previous studies. Both species exhibited an association of their genetic structure with environmental variables. D. bozinovici exhibited significant associations of allelic frequencies with elevation, precipitation during the warmest periods, and seasonality in the thermal regime. For D. gliroides, genetic variation appeared to be associated with more variables than D. bozinovici, including precipitation and temperature-related variables, isothermality, and elevation. All the outlier SNPs were mapped to the D. gliroides reference genome to explore if they fell within functionally known genes. These results represent a necessary first step toward identifying the genome regions that harbor genes associated with climate adaptations in Dromiciops. Notably, we identified genes involved in various functions, including carbohydrate synthesis (ALG8), muscle and neuronal regulation (MEF2D), and stress responses (PTGES3). Ultimately, this study contributes valuable insights that can inform targeted conservation strategies aimed at preserving the genetic diversity of Dromiciops in the face of environmental challenges.