Isolation to Extinction: Landscape Fragmentation and Connectivity in Sloth Bears of the Indian Terai

Abstract

Habitat fragmentation is a major global threat to biodiversity, leading to small and isolated populations. Fragmented landscapes can reduce connectivity, erode genetic diversity, and increase inbreeding risk, potentially contributing to local extinction. Using a landscape genetics approach, we investigated sloth bear (Melursus ursinus) populations in Indian Central Terai landscape - a human-dominated, multi-use region that exemplifies the challenges of conserving wildlife populations in highly fragmented landscapes. Using non-invasively collected faecal samples (n=209), we identified 66 individuals from 964 genome-wide SNPs generated via ddRAD sequencing. Spatial genetic structuring was not strictly congruent to the protected areas and genetic clusters showed low genetic diversity (mean HE = 0.156 ; mean HO = 0.079) with a heterozygote deficit (mean FIS = 0.323). Further, landscape genetic analyses revealed agriculture as the primary barrier to gene flow across the landscape, followed by proximity to water. Our findings establish the first genetic baseline for sloth bears in this region and suggest that historical population structure and contemporary fragmentation may jointly influence genetic connectivity and diversity across the landscape. We demonstrate the unique utility of non-invasive samples and genome-wide SNP based analyses for poorly studied species of conservation concern, despite experimental and bioinformatic challenges. Our novel insights underscores the importance of such genetic monitoring in fragmented landscapes.