Through the lynx’s lens: Genetic insights from the Eurasian lynx (Lynx lynx) in France

After its extinction in France in the early 20th century, the Eurasian lynx (Lynx lynx) was reintroduced in the Swiss Jura in the 1970s from a small number of Carpathian founders and later recolonised the French Jura and the Northern Alps through natural dispersal. Despite this recovery, this population remains small, isolated and threatened, making updated genetic information essential for conservation. Here, we present an up-to-date and fine-scale assessment of its genetic diversity, structure and gene flow, using 227 non-invasive lynx scat samples collected between 2019 and 2025 through a citizen science network. Our analyses combined samples previously used within a PhD framework with newly genotyped scats, providing an expanded dataset for robust interpretation.
Based on mitochondrial DNA and two sets of microsatellite markers, our results revealed a complex genetic pattern. While genetic structuring suggests ongoing gene flow across the study area, and genetic diversity (allelic richness = 3.18, Ho = 0.38, He = 0.42) aligns with levels observed in other reintroduced Eurasian lynx populations, the absence of mitochondrial diversity, a positive inbreeding coefficient (FIS = 0.19, 95% CI: 0.14-0.26), and the population’s geographic isolation, collectively point to a persistent founder effect.
These findings support recent scientific recommendations, informed by extensive modelling, that call for genetic reinforcement. Such an intervention should be combined with efforts to improve habitat connectivity, reduce human-induced mortality, strengthen transboundary cooperation, and enhance social acceptance, to prevent further genetic erosion and ensure the species’ long-term conservation.