Integrating Historical biogeography and Pliocene climate fluctuation to Unraveling the evolution of Tigris-Euphrates drainage basin through widespread freshwater Barbinae (Cypriniformes: Cyprinidae)

The formation history of the Tigris-Euphrates basins (TEB) and Karun River remains mostly unknown. To unravel the evolutionary history of the TEB and Karun River, we integrated the biogeography and climatic niche models of the freshwater fish with the largest natural distribution pattern. This study investigates 16 species of the Barbinae subfamily with wide distributions and high diversity. Mitochondrial <i>Cytb</i> and COI genes were obtained from various locations via GenBank and utilized to generate a dated phylogeny and reconstructed ancestral areas with the BioGeoBEARS model. We used the BAMM tools to estimate rates of diversification through time. Furthermore, by integrating potential geographic distribution with four spatial climate variables including max temperature of warmest month, min temperature of coldest month, temperature annual range and annual precipitation, we reconstruct ancestral predicted niche occupancy (PNO) profiles using ecological niche modeling (ENM) method. Based on the evolution of endemic TEB and Karun River Barbinae, we hypothesize that ancestral clades appeared in the TEB in the late Oligocene/early Miocene (∼23.12 Mya) and dispersed to the basin from the mid-Miocene onward (∼14.33 Mya). Our results suggest that the mid-Miocene uplift of the Zagros Mountains likely impacted Karun River flow in southwestern Iran, contributing to the observed diversification patterns in Barbinae. In addition, niche divergence was dominant in Barbinae diversification, alongside phylogenetic niche conservatism. The study introduces a method combining phylogenetic, biogeographic, and niche modeling data to explore freshwater fish evolution in the Tigris-Euphrates and Karun basins, highlighting geological impacts on biodiversity and diversification processes.