The genetic population structure of Lake Tanganyika's Lates species flock, an endemic radiation of pelagic top predators

Life history traits are important factors in shaping gene flow within species, and these traits can thus be determinants of whether a species exhibits genetic homogeneity across its range, or considerable population structure. Furthermore, understanding genetic connectivity plays crucially into species conservation decisions, and genetic connectivity is an important component of modern fisheries management in fishes exploited for human consumption. In this study, we investigated the four endemic Lates species of Lake Tanganyika (Lates stappersii, L. microlepis, L. mariae and L. angustifrons), sampled along the Tanzanian shoreline, using reduced-representation genomic sequencing methods. Based on previous studies, we predicted little genetic population structure in the entirely pelagic L. stappersii and the predominantly pelagic L. microlepis. In contrast, we expected the highest genetic differentiation in populations of L. mariae, which is the most resident and for which females aggregate over spawning grounds. We predicted that L. angustifrons would show intermediate structure. We indeed find the most strongly differentiated genetic clusters in L. mariae. However, contrary to our predictions, we find evidence for genetically distinct (albeit weakly differentiated) groups within the pelagic L. stappersii and L. microlepis, and no genetic structure in L. angustifrons. We call for management approaches accounting for genetically differentiated populations of L. stappersii, L. microlepis, and L. mariae, which are commercially important species in the region.