Lineages to landscapes: Mitogenomic insights and climate refugia informing proactive conservation of the Endangered Tricarinate Hill Turtle (Melanochelys tricarinata) in the Indian Subcontinent

The Tricarinate Hill Turtle Melanochelys tricarinata , endemic to the Indian subcontinent, is classified as ‘Endangered’ due to anthropogenic pressures and climate change. The present study adopts a parallel approach by characterizing the complete mitogenome and evaluating current and future habitat suitability. The mitogenome, spanning 16,745 bp, comprises 37 genes, with most protein-coding genes beginning with the canonical ATG start codon. The codon usage analysis revealed that arginine, leucine, and serine are the most frequently used amino acids. The control region contains key regulatory elements, including a termination-associated sequence, four conserved sequence blocks, and two distinct tandem repeat motifs. The phylogenetic assessment using both Bayesian inference and Maximum-likelihood methods consistently placed M. tricarinata in a distinct clade, separate from other geoemydid taxa, and identified it as an ancestral lineage to Sacalia , Notochelys , Heosemys , and Cyclemys . The ensemble model identified suitable habitats under both current and future climate scenarios. Under present scenario, approximately 374,657 km² of suitable habitat was delineated within the training extent with a mean corridor connectivity of 0.377, which was reduced to 238,039 km² when restricted to existing forest cover. The future projections indicate a potential loss of up to 40% in suitable habitat area due to climate change, accompanied by increased fragmentation, reduced patch size, and decreased connectivity. Thus, this study provides comprehensive insights into the evolutionary history and ecological requirements of M. tricarinata , offering a critical scientific foundation to guide effective conservation and management strategies for this imperiled species across its native range.