Nikola Tkáčová, Faculty of Science, Charles University

Population status is often communicated as census size, but long-term persistence depends on evolutionary capacity and human-driven mortality. By integrating spatial demography with genetic monitoring, we address the mismatch between perceived bear abundance and actual population viability in the Western Carpathians. We analysed the brown bear population across Slovakia using non-invasive genetic detections collected in two seasons (2019–2021; >2,100 samples; 614 identified individuals). We fitted sex-explicit spatial capture–recapture models with habitat-dependent inhomogeneous density, using a habitat suitability surface to map density and propagate uncertainty across the range. Spatial models yielded census size (Nc) on the order of ~1,000 bears, while revealing strong concentration of density in high-suitability cores and spatial heterogeneity that is invisible to non-spatial summaries. To quantify evolutionary resilience, we estimated effective population size with linkage-disequilibrium and sibship methods; both indicated Ne consistently < 200 (Ne/Nc < 0.2). These findings highlight a mismatch between abundance and genetic diversity, suggesting limited adaptive capacity consistent with geographic isolation and reduced gene flow. Population viability analysis (PVA) over 100 years projects declines in genetic diversity and high sensitivity of population trajectories to modest parameter shifts. Finally, we contrasted these findings with national mortality records (2007–2025), documenting a sharp recent rise in anthropogenic mortality, reaching a peak in the most recent year. Spatial demography, low Ne, and accelerating mortality, together with the increasing likelihood of black swan events in the Great Acceleration era, suggest that a seemingly abundant population may be closer to a viability threshold than census size alone implies, motivating management to jointly monitor spatial distribution, genetic diversity and mortality trends.