Domestication traits and adaptive evolution in blunt snout bream (Megalobrama amblycephala) by artificial selection pressure

Abstract

Megalobrama amblycephala, a herbivorous freshwater fish species native to China, has become an important aquaculture species in Chinese freshwater polyculture systems due to its high economic value. How morphological traits and gene expression of cultured populations are influenced by different artificial selection pressures compared to wild populations is still poorly understood. In the current study, a combination of morphological analysis, cytochrome b sequence characterization, and whole genome re-sequencing methods was employed to investigate the genetic differences caused by artificial selection, including the genetic diversity and differentiation of wild and cultured populations. The genetic diversity of the population was classified based on the cytochrome b gene as follows: wild population (WP) > common breeding population (CP) > artificially created strain (AS). Morphological traits showed that the values of head length, body depth, dorsal fin length and pelvic fin length were the largest in the WP, smaller in the CP and the smallest in the AS. But the largest body width was in the AS, smaller in the CP, and the smallest in the WP. A significant finding was the identification of several candidate genes involved in carbohydrate metabolism, including Adcy9, Eif4ebp1, Gnai2b, Ppp1r3b, Ptprfa, Ptprfb and Slc8a2b. The data generated by this research not only contribute to a deeper understanding of the molecular-level characteristics but also provide crucial scientific foundations for the conservation and genetic improvement of this species.