Freshwater ecological decline in the southern Zagros Basins of Iran: Genetic, ecological, and morphological divergence of Potamon strouhali

Freshwater ecosystems are increasingly threatened by climate change and basin fragmentation, leading to significant biodiversity loss. To investigate these critical phenomena, scientists utilize specific animal species as effective ecological indicators, providing cost-effective assessments of ecosystems health and prompting strategies for environmental sustainability. We used Potamon strouhali populations as indicators to assess potential ecological changes in freshwater basins of the southern Zagros Mountains by employing integrative approaches. Haplotype network revealing nine distinct haplogroups, each characterized by unique haplotypes that do no overlap with others. An analysis of molecular variance (AMOVA) demonstrated significant genetic variation among populations (86.46%) compared to within-population variation (0.6%). Additionally, a time-calibrated phylogenetic tree based on COI and 16S sequences indicated that the divergence time of two distinct morphotype clades occurred approximately two million years ago, likely due to the emergence of Kazerun fault. We conducted an ecological identity test and variable importance analysis based on 80 presence localities across their distribution range, revealing minimal ecological overlap between the two morphological lineages. The limited haplotype diversity in P. strouhali populations suggests restricted gene flow, likely due to habitat fragmentation and harsh conditions, signaling ecosystem decline. Conservation efforts are urgently needed to protect biota and habitat diversity and integrity in the freshwater ecosystems, especially since regional extinctions have been observed.