Microevolution and adaptive divergence in relict bear populations

All cells in a living organism contain essentially the same DNA. However, cells can use the information contained in the genetic code differently, depending on the functions they need to perform. This modulation of gene expression occurs through epigenetic modifications, which, at least in part, can be influenced by the environment. These modifications regulate the expression of genes without altering their DNA sequence.

In contrast, the study of epigenomics, which has been widely established in biomedical fields and in model species, represents an innovative research frontier for wild animal populations. There is strong evidence to suggest that information derived from the epigenome is critical to fully understanding the processes of adaptation and resilience in populations. As a result, epigenomics could prove to be a crucial tool for the conservation and management of many animal species.

The PRIN project “Epigenetics and conservation of small populations: microevolution and adaptive divergence in relict bear populations” carried out in collaboration with the University of Rome La Sapienza and the University of Isubria, aims to deepen our knowledge of epigenomic variation and its relationship to phenotypic plasticity in mammals, with a particular focus on small relict populations characterized by low genetic variability and of conservation significance.

An emblematic example is the Marsican brown bear, an isolated population of about 50 individuals, which has a high rate of inbreeding, low genetic diversity, and an accumulation of deleterious mutations. Despite this, these bears show unique morphological and behavioral characteristics, which may reflect local adaptations mediated by the epigenome. Understanding the origin and evolution of these adaptations is crucial for the management and conservation of this population.

This research aims to compare the genomic and epigenomic profiles of brown bears to identify possible correlations with phenotypic variation. The goal is to test whether epimutations can compensate for genetic erosion by promoting phenotypic plasticity and adaptability. The results of this study could reveal how phenotypic plasticity persists even in genetically depleted populations, offering new information useful for planning strategies to conserve vulnerable species.

Integration of genomic, epigenomic and transcriptomic profiles will be used to describe adaptive and evolutionary pathways and to assess how current phenotypic variants have emerged, become established and are maintained in bear populations. The results will provide new insights into functional and nonneutral variation in small and highly consanguineous populations, thus enabling robust inferences about adaptive processes and the additive effects of consanguinity in populations that have suffered demographic bottlenecks.