Cytochrome b Mitochondrial Gene Revealed a Strong Genetic Differentiation between Two Populations of the Endemic Freshwater Fish Moroccan Loach Cobitis maroccana Pellegrin, 1929

Cobitis maroccana, also known as the Moroccan loach, is an endemic freshwater fish found in the rivers of the Loukkos and Sebou basins in Morocco. In order to gain a better understanding of the genetic differentiation within C. maroccana from the Loukkos and Sebou populations, a comprehensive study was conducted, focusing on the mitochondrial cytochrome b gene. A total of 30 sequences of the complete cytochrome b (1140 bp) were obtained from C. maroccana specimens. Through a combination of phylogenetic analysis, phylogeographic assessments, as well as the estimation of the Fst index, the research outcomes revealed significant genetic differentiation between the two juxtaposed basin populations. Notably, each of these basins displayed unique and distinct haplotype groups within the C. maroccana specimens. These intriguing findings strongly suppose that the populations in the Loukkos and Sebou basins have become reproductively isolated from each other over time, indicating limited or no interbreeding between them.