Evaluation of Genetic Structure and Connectivity among Populations of Macrozoobenthic Snail (Mutela rubens) from Freshwater Ecosystems in Kano State, Nigeria

Abstract

Macrozoobenthic snails are important bioindicators and fish food organisms in freshwater ecosystems, yet population genetic data for many Nigerian freshwater molluscs remain scarce. This study evaluated the genetic structure and connectivity among populations of the macrozoobenthic freshwater snail Mutela rubens from River Kano, River Bagwai and River Karaye in Kano State, Nigeria, using Random Amplified Polymorphic DNA (RAPD) markers. A total of 96 specimens were analyzed and genetic variation was assessed using five RAPD primers, which generated 82 reproducible loci. Genetic polymorphism ranged from 56.10% to 63.41%, with the highest variation recorded in River Kano (63.41%), followed by River Bagwai (59.76%) and River Karaye (56.10%). Genetic diversity indices revealed higher heterozygosity in River Kano (0.205), while River Karaye recorded the lowest value (0.182), indicating differences in genetic variability and population connectivity. Nei’s genetic distance analysis showed moderate genetic differentiation among populations, with values ranging from 0.082 to 0.136, while genetic identity ranged from 0.873 to 0.921. Molecular analysis of variance revealed that 72% of the total genetic variation occurred within populations, whereas 28% was attributed to differences among populations. UPGMA dendrogram grouped the three populations into closely related clusters without genetic outliers. The findings demonstrate that M. rubens populations in Kano State freshwater ecosystems possess considerable genetic diversity and connectivity, although localized environmental factors may influence their genetic structuring.