Genome-wide evidence of environmentally mediated secondary contact of European green crab (Carcinus maenas) lineages in eastern North America

Genetic-environment associations are increasingly revealed through population genomic data and can occur through a number of processes, including secondary contact, divergent natural selection, or isolation-by-distance. Here we investigate the influence of the environment, including seasonal temperature and salinity, on the population structure of the invasive European green crab (Carcinus maenas) in eastern North America. Green crab populations in eastern North America are associated with two independent invasions, previously shown to consist of distinct northern and southern ecotypes, with a contact zone in southern Nova Scotia, Canada. Using a RAD-seq panel of 9137 genome-wide SNPs, we detected 41 SNPs (0.49%) whose allele frequencies were highly correlated with environmental data. A principal components analysis of 25 environmental variables differentiated populations into northern, southern, and admixed sites in concordance with the observed genomic spatial structure. Furthermore, ...

遗传-环境关联正日益通过群体基因组数据得以揭示，其形成可经由次生接触、歧化自然选择、距离隔离等多种演化过程。本研究以北美东部的入侵物种欧洲绿蟹（*Carcinus maenas*）为研究对象，探讨包括季节性温度与盐度在内的环境因子对其种群结构的影响。北美东部的绿蟹种群与两次独立入侵事件相关，此前研究已证实该种群存在分化显著的北方与南方生态型，二者的接触带位于加拿大新斯科舍省南部区域。本研究利用包含9137个全基因组单核苷酸多态性（Single Nucleotide Polymorphism, SNP）位点的限制性位点关联DNA测序（Restriction-site Associated DNA sequencing, RAD-seq）基因分型面板，检测到41个SNP位点（占总位点数的0.49%）的等位基因频率与环境数据呈高度相关。对25项环境变量开展主成分分析后，可将采样种群划分为北方、南方以及混合遗传背景的类群，该结果与观测到的基因组空间结构高度一致。此外，……