Frozen and Scorched: Genomic Signatures of Adaptive Divergence and Hibernation in the Living Fossil
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
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 (), a small marsupial considered a living fossil, exhibits torpor, hibernation, and aestivation as key survival strategies. In this study, we investigated genomic adaptations inand 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. At the ancestralnode, positive selection was detected in, and, 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,andshow no overlap in positively selected genes:presents additional signals in LSS and RASL11B, related to sterol and stress‐response metabolism, whileshows signatures of broad thermal stress tolerance through HSPA2. These findings underscore unique adaptations possibl
Abstract
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 (), a small marsupial considered a living fossil, exhibits torpor, hibernation, and aestivation as key survival strategies. In this study, we investigated genomic adaptations inand 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. At the ancestralnode, positive selection was detected in, and, 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,andshow no overlap in positively selected genes:presents additional signals in LSS and RASL11B, related to sterol and stress‐response metabolism, whileshows signatures of broad thermal stress tolerance through HSPA2. These findings underscore unique adaptations possibly linked to hibernation inand species‐specific differences. We evaluated adaptation to torpor and hibernation in the genusby comparing it with both torpid and non‐torpid marsupials, and investigated divergent selection signals between its two species. For the ancestral node, we identified positive selection in the genes PFKFB2, LAMP3, OTX1, and RAPSN, alongside an enrichment of pathways potentially linked to hibernation, which aligns with our gene family expansion findings. No overlap of genes under selection was found between species; specific signals were identified in LSS and RASL11B for, and in HSPA2 for. graphical