Cladistic Relationships and Landscape Genetics of the Endangered Indian Peacock Softshell Turtle Nilssonia hurum (Gray, 1830): Implications for Strategic Conservation Planning.

The endangered Peacock Softshell Turtle Nilssonia hurum (Gray, 1830) has undergone a steep population decline in recent decades because of habitat loss and anthropogenic pressures, highlighting the urgent need for scientific intervention to ensure its protection in the wild. Thus, the present study integrates mitogenomic and ecological data to guide proactive conservation strategies for this species. The study reports the first mitogenome (16,788 bp) of N. hurum from the upper Ganges region, which exhibits a typical gene composition and strong A + T bias. The mitogenome-based phylogenetic analyses reveal the monophyly of the genus Nilssonia Gray, 1872 and a close evolutionary relationship between N. hurum and N. nigricans (Anderson, 1875). The genetic distance and haplotype network analyses on the basis of the CYTB gene reveal substantial intraspecific diversity and spatial genetic structuring among populations across river basins within the easternmost range. Using species distribution modeling, the study identified 123,699 km2 (6.81% of IUCN range) as presently suitable for N. hurum. However, future climate projections indicate drastic reductions in suitable habitat, with losses of up to 85% due to climate change. The landscape genetic analyses revealed that the Meghna basin exhibits the highest mean functional connectivity (0.603), whereas the Brahmaputra basin shows the lowest connectivity (0.198) despite containing suitable habitat patches, consistent with its high genetic diversity. Moreover, projections under future climate scenarios, driven by anticipated losses in habitat suitability, indicate widespread declines in functional connectivity across all basins and sub-basins. The landscape geometry assessments further reveal increasing habitat fragmentation due to climate change. Therefore, populations persisting within suitable habitat patches across different river basins in the eastern range should be prioritized as distinct conservation units for future management. Overall, this study provides a critical foundation for site-specific conservation planning through landscape genetics to address habitat loss, fragmentation, and mitigating inbreeding depression for ensuring the long-term endurance of this threatened freshwater turtle in South Asia.