Frozen and Scorched: Genomic Signatures of Adaptive Divergence and Hibernation in the Living Fossil Dromiciops

ABSTRACT

Adverse historical conditions shape biodiversity by driving demographic shifts and genomic divergence through evolutionary mechanisms. Selective pressures foster adaptive strategies in response to extreme environments, with hibernation as a key example. The expression of torpor and its various forms exemplify such adaptations. However, the genomic basis of these processes and the influence of evolutionary forces, particularly natural selection, remain largely unexplored. The Monito del Monte ( Dromiciops ), a small marsupial considered a living fossil, exhibits torpor, hibernation, and aestivation as key survival strategies. In this study, we investigated genomic adaptations in Dromiciops and their potential relationship with the physiological state of torpor and hibernation. Historical climate change, along with varying expansions and bottlenecks, appears to have shaped the genetic diversity and local adaptation of Dromiciops . At the ancestral Dromiciops node, positive selection was detected in PFKFB2, LAMP3, OTX1 , and RAPSN , alongside enrichment in the MAPK signaling and steroid hormone biosynthesis pathways—both previously implicated in hibernation physiology. Gene family expansions further converged on mitochondrial maintenance and redox regulation. At the species level, D. gliroides and D. bozinovici show no overlap in positively selected genes: D. gliroides presents additional signals in LSS and RASL11B, related to sterol and stress‐response metabolism, while D. bozinovici shows signatures of broad thermal stress tolerance through HSPA2. These findings underscore unique adaptations possibly linked to hibernation in Dromiciops and species‐specific differences.