Genetic Diversity and Phylogeography of the African Softshell Turtle (Trionyx triunguis) in Nigerian River Systems, South South and South East Nigeria

This study investigates the genetic diversity and phylogeographic structure of the African softshell turtle Trionyx triunguis across four major river systems in South South and South East Nigeria. Trionyx triunguis is subject to intense hunting pressure for bushmeat and traditional medicine, yet its population genetic structure in Nigerian rivers is entirely uncharacterised, making it impossible to define conservation management units. Blood and tissue samples were collected from 94 individuals across the Cross, Imo, Anambra, and Benue Rivers using trap and artisanal fisher sampling. Mitochondrial DNA (cytochrome b, ND4, and control region) was sequenced to assess haplotype diversity, and 14 microsatellite loci were genotyped to assess nuclear genetic diversity and differentiation. Phylogenetic analysis using maximum likelihood and Bayesian approaches was conducted against GenBank reference sequences. Results revealed moderate mitochondrial haplotype diversity but low nuclear heterozygosity, consistent with the effects of sustained harvesting on effective population size. Significant genetic differentiation (FST = 0.14) was detected between Cross River and Niger drainage populations, indicating limited gene flow across the watershed divide and supporting recognition of these as distinct management units. No evidence of recent population bottleneck was detected in haplotype distributions. The study provides the first molecular conservation genetics dataset for Trionyx triunguis in Nigeria and recommends separate management of Cross River and Niger drainage populations with harvest quotas calibrated to genetic effective population size. Keywords: Trionyx triunguis, genetic diversity, phylogeography, conservation genetics, Nigerian river systems.