Genetic Diversity and Population Dynamics in Bear Species

Genetic diversity in bear species reflects a complex interplay of evolutionary history, ecological adaptation and human influence. From polar ice sheets to tropical montane forests, bears occupy a broad range of habitats that have shifted dramatically during Quaternary climatic cycles. These shifts drove repeated range expansions and contractions, leaving genetic imprints detectable in both nuclear and mitochondrial genomes. Contemporary fragmentation, hunting pressure and conservation interventions further modulate gene flow and demographic trajectories. Autosomal genome surveys often mirror recent connectivity, whereas mitochondrial and Y-chromosomal markers retain deeper phylogeographic signals owing to sex-biased dispersal and lineage sorting. Hybridisation between sympatric species can introduce adaptive variants but also complicates taxonomic boundaries. Microsatellite panels remain valuable for resolving fine-scale population structure, while whole-genome approaches identify loci under selection for environmental resilience. Integrating these genomic insights is crucial for designing management strategies that maintain genetic variation, promote connectivity and safeguard bear populations in a rapidly changing world.

Research from Nature Portfolio

Recent genome-wide analyses of brown bears have fundamentally revised interpretations of population structure. By comparing autosomal, X-chromosomal and uniparental markers across the species’ circumpolar range, studies show that contemporary genetic clustering largely reflects recent male-mediated dispersal rather than solely postglacial recolonisation pathways. Forward-in-time simulations reveal that ongoing gene flow can erase ancient autosomal signals more rapidly than those in mitochondrial or Y-chromosomal regions, explaining discordances among marker classes. In South America, targeted surveys of Andean bears combining mitochondrial sequences with species-specific microsatellites uncovered previously unrecognised genetic subdivisions and higher levels of diversity in Ecuadorian populations. These findings underscore the importance of using appropriate marker systems to delineate conservation units and guide habitat connectivity initiatives.

Genetic Diversity and Population Dynamics in Bear Species publication trend

The graph below shows the total number of articles in genetic diversity and population dynamics in bear species across all publications each year (not limited to Nature Index journals).

Technical terms

Autosomal: Chromosomes inherited from both parents, comprising the majority of the nuclear genome.

Mitochondrial DNA (mtDNA): Organellar genetic material passed maternally, used to trace maternal lineages and historical demography.

Microsatellite markers: Short tandem repeats in nuclear DNA that are highly polymorphic and useful for assessing population structure.

Introgression: Incorporation of genetic material from one species into another through hybridisation and backcrossing.

Phylogeography: The study of the geographic distribution of genetic lineages and the historical processes shaping them.

References

1. Range-wide whole-genome resequencing of the brown bear reveals drivers of intraspecies divergence. Communications Biology (2023).
2. Evidence of population genetic structure in Ecuadorian Andean bears. Scientific Reports (2024).
3. Phylogeography of introgression: Spatial and temporal analyses identify two introgression events between brown and American black bears. Heredity (2025).
4. Late Pleistocene polar bear genomes reveal the timing of allele fixation in key genes associated with Arctic adaptation. BMC Genomics (2024).
5. Genetic and demographic recovery of an isolated population of brown bear Ursus arctos L., 1758. PeerJ (2016).