Adaptive evolution of different geographical populations of Culter alburnus

Geographically separated populations of Culter alburnus in China exhibit marked physiological and behavioral characteristics, particularly between populations inhabiting the northern and southern part of Huai River (HR), indicating their adaptation to local environments. In this study, the morphological characteristics of C. alburnus were measured, and restriction site associated DNA (RAD) sequencing was used for C. alburnus to investigate the genomic features of the Xingkai Lake (XKL) population from the northern part and HR, Yangtze River (YR), and Dianshan Lake (DSL) populations from the southern part of China. Analyses results revealed significant morphological differences and population genetic structure among these populations, with pronounced genetic differentiation between the northern and the southern part. Notably, the northern (XKL) population exhibited significantly lower genetic diversity than the other three southern populations. Furthermore, genes involved in synaptic vesicle transmission regulation, androgen receptor signaling, and behavior regulation pathways, including oligophrenin 1, ch25h13, androgen receptor, and Rho kinase genes, showed selection signals with high genetic differentiation indices (Fst), significant nucleotide diversity (Pi) differences, and significantly differential expression values in the northern (XKL) population compared with southern populations. These findings indicate that these genes may influence the different adaptive reflex behavioral responses of northern and southern C. alburnus populations. This study highlights the genetic structure and adaptations of C. alburnus, providing important resources for its management and aquaculture.