EXAMINING THE EFFECTS OF HABITAT FRAGMENTATION ON GENETIC DIVERSITY IN ENDANGERED AMPHIBIAN POPULATIONS

Abstract

Habitat fragmentation poses a critical threat to the genetic integrity of endangered amphibian populations by disrupting gene flow and reducing effective population sizes. In this study, we evaluated the relationship between landscape fragmentation and genetic diversity across six ecoregionally distinct sites using high‐resolution remote sensing metrics (patch density, edge density, mean patch size, isolation distance) and single nucleotide polymorphism (SNP) genotyping (~10,000 loci). Fragmentation varied from 7.4 to 15.3 patches/km² and 78.9 to 130.8 m/ha edge density, with mean patch sizes of 2.1–6.1 ha. Genetic analyses revealed observed heterozygosity (Ho) ranging from 0.38 to 0.60 and allelic richness from 3.8 to 6.0. Principal component analysis of SNP data explained 81.5% of variance within five components, while Mantel and partial Mantel tests confirmed strong correlations between genetic distance and fragmentation (r = 0.62, p = 0.001; r = 0.48, p = 0.005). Generalized linear models identified critical fragmentation thresholds—patch density >10.5 patches/km², edge density >95 m/ha, mean patch size <3.8 ha, and isolation distance >220 m—beyond which genetic diversity declines significantly (all p < 0.01). Our findings underscore the need to maintain contiguous habitat patches and functional corridors to preserve amphibian genetic resilience. We recommend that conservation planning incorporate these empirically derived thresholds into land‐use policies and restoration efforts. Future research should expand taxonomic breadth, integrate species‐specific dispersal data, and assess the efficacy of targeted interventions such as assisted gene flow. By delineating actionable fragmentation limits, this work provides a robust framework for safeguarding amphibian adaptive capacity in fragmented landscapes.