A migration-associated supergene reveals loss of biocomplexity in Atlantic cod

Chromosome structural variation may underpin ecologically-important intraspecific diversity by reducing recombination within supergenes containing linked, co-adapted alleles. Here, we confirm that an ancient chromosomal rearrangement is strongly associated with migratory phenotype and individual genetic structure in Atlantic cod (Gadus morhua) across the Northwest Atlantic. We reconstruct trends in effective population size over the last century, and for the first time reveal declines in effective population size matching onset of industrialized harvest (post 1950). We find different demographic trajectories between individuals homozygous for the chromosomal rearrangement relative to heterozygous or homozygous individuals for the non-inverted haplotype, suggesting different selective histories across the last 150 years. These results illustrate how chromosomal structural diversity can mediate fine-scale genetic, phenotypic and demographic variation in a highly connected marine species, ...染色体结构变异（Chromosome structural variation）或可通过降低携带连锁共适应等位基因的超基因（supergenes）内的重组率，调控具有生态重要性的种内多样性。本研究证实，在西北大西洋海域的大西洋鳕（Gadus morhua）中，一处古老的染色体重排与洄游表型及个体遗传结构显著相关。我们重构了近一个世纪以来的有效种群大小（effective population size）变化趋势，并首次揭示了有效种群大小的下降与1950年后工业化捕捞（industrialized harvest）的启动时间相吻合。相较于携带非倒位单倍型（non-inverted haplotype）的杂合（heterozygous）或纯合（homozygous）个体，携带该染色体重排纯合子的个体呈现出不同的种群动态轨迹（demographic trajectories），这表明二者在过去150年中经历了不同的选择历史（selective histories）。这些结果阐明了染色体结构多样性如何在高度连通的海洋物种中介导精细尺度的遗传、表型及种群动态变异……