Genes underlying adaptive physiological shifts among hibernating mammals

Hibernation has evolved independently in several mammalian lineages,
allowing animals to survive extreme environmental conditions through
profound physiological shifts, including reduced metabolic rate, heart
rate, respiration, and body temperature. These physiological shifts allow
hibernators to rely solely on fat reserves, simultaneously avoiding the
adverse effects of prolonged immobility seen in non-hibernating species.
Although research on individual species has highlighted key aspects of
these adaptations, the genetic basis of hibernation across mammals remains
poorly understood. Synthesizing both single species and comparative
approaches, we use metabolomic data from waking and hibernating black
bears (Ursus americanus) to guide bioinformatic analyses of genes using
tests of selection and evolutionary rate convergence across independent
lineages of hibernating mammals. Our analyses reveal significant changes
in carnitine levels between states. Using public databases we generate
candidate genes which may contribute to regulation of carnitine, and use
these to test for signatures of selection across several independent
lineages of hibernating mammals. We also utilize a dataset of 19k proteins
across 120 mammalian genomes to identify genes evolving at convergent
rates across hibernating mammals.  Using both approaches, we find
several novel genes likely to impact carnitine metabolism and related
functions vital to hibernation such as metabolic shifts, oxidative stress,
and tissue preservation. These findings provide new insights into the
genetic basis of hibernation and offer promising targets for translational
research, including the development of clinical therapies that mimic
hibernation-like states for applications in medicine and space
exploration.