Dynamic body size evolution during speciation of predatory cichlid fishes in the Lake Malawi superradiation

endemic to Lake Kingiri, a small (600 m diameter) crater lake geographically isolated from the main body of Lake Malawi but within the catchment. We show that these two ecomorphologically divergent sympatric species-one small-bodied, the other larger-bodied-share a unique common ancestor and diverged from one another ∼2000 years ago. We demonstrate strong directional selection focused on the larger-bodied Kingiri species, specifically on genetic variants connected to genes with anatomical development and nervous system function. Collectively, these results are supportive of body size-associated speciation taking place rapidly in the Lake Malawi cichlid fish superradiation. We conclude that body size-associated genetic variants have been important targets of selection during large-scale cichlid fish diversification, including in a crater lake sympatric speciation context.