GENETIC SIGNATURES OF SOCIAL BEHAVIOR EVOLUTION IN TANGANYIKA CICHLIDS

The molecular mechanisms underlying social behavior in vertebrates remain largely unresolved, despite numerous candidate genes and pathways being implicated. Understanding how genetic variation contributes to social phenotypes is critical for uncovering the evolutionary processes shaping complex behaviors. Here, we investigate the genetic basis of social traits across the cichlid radiation of Lake Tanganyika, a system characterized by repeated evolutionary transitions in pair-bonding – as a proxy for social recognition – , group size, and the sex of the caregiver.
We analyzed coding sequence evolution of genes involved in social behavior, including candidates from KEGG pathways and other genes suggested to regulate social traits. Over 100 genes show gene-wide signatures of positive selection, with many evolving faster in species exhibiting pair-bonding. Notably, Notch3 exhibits strong evidence of positive selection, and functional validation supports its involvement in social recognition.
Although gene expression analyses are still ongoing, preliminary results indicate that multiple genes contribute to variation in the three social phenotypes, highlighting potential regulatory mechanisms underlying social behavior. Together, these findings integrate coding and regulatory evolution to identify molecular pathways involved in social trait diversity and provide a foundation for future functional studies linking genetic variation to behavioral phenotypes.