Unveiling population dynamics and diversity in two European brown bear (Ursus arctos) populations through non-invasive SNP genotyping

Non-invasive genetic analyses enable monitoring and understanding of population dynamics without disturbing wild animals. We present a non-invasive genetic method to identify and characterize the brown bear populations of Cantabrian and Pyrenean (of Slovenian origin). We selected an efficient 61-SNP panel to genotype more than 2,000 non-invasive samples from both populations. Results showed successful genotyping of 1,639 bear samples, revealing 400 distinct individuals. Genetic diversity was similar in both populations, and differentiation between populations was highly significant. The Pyrenean population did not show genetic substructuring despite the influence of the breeding male “Pyros”. In contrast, two subpopulations were observed in the Cantabrian population. Furthermore, analyses indicated a sex ratio bias in the Cantabrian population, potentially influenced by male dispersal and landscape features. Overall, the study demonstrates the utility of non-invasive genetic methods for monitoring and understanding bear populations, highlighting differences between the Pyrenean and Cantabrian populations, and providing insights into their genetic diversity, structure, and demographic trends.