The Genomic Basis of the Genetic Differentiation and Local Adaptive Evolution of Pampus Echinogaster based on SLAF-seq

Abstract

Background: Factors such as climate change (especially ocean warming) and overfishing have led to a decline in the supply of Pampus echinogaster and a trend of decreasing age. Exploring the genetic structure and local adaptive evolutionary mechanisms is crucial for the management of P. echinogaster. Results: This population genomic study of nine geographical populations of P. echinogaster in China was conducted by specific-locus amplified fragment sequencing (SLAF-seq). A total of 935,215 SLAF tags were obtained, and the average sequencing depth of the SLAF tags was 20.80×. After filtering, a total of 46,187 high-consistency genome-wide single nucleotide polymorphisms (SNPs) were detected. Based on all SNPs, the overall genetic diversity among the nine P. echinogaster populations was high. The Shantou population had the lowest genetic diversity, and the Tianjin population had the highest. Meanwhile, the population genetic structure based on all SNPs revealed significant gene exchange and insignificant genetic differentiation between the nine P. echinogaster populations. Based on pairwise genetic differentiation (FST), we further screened 1,852 outlier SNPs that might have been affected by habitat selection and annotated SLAF tags containing these 1,852 outlier SNPs using Blast2GO. The annotation results showed that the genomic sequences at the outlier SNPs were mainly related to material metabolism, ion transport, breeding, stress response, and inflammatory reactions, which may be related to the adaptation of P. echinogaster to different environmental conditions (such as water temperature and salinity) in different sea areas.Conclusions: The high genetic similarity of nine P. echinogaster populations may have been caused by the population expansion after the last glacial period, the lack of balance between migration and genetic drift, and the long-distance diffusion of eggs and larvae. We suspected that variation of these genes associated with material metabolism, ion transfer, breeding, stress reactions, and inflammatory reactions were critical for adaptation to spatially heterogeneous temperatures in natural P. echinogaster populations.