The mode and extent of rapid evolution and genomic change in response to human harvesting are key conservation issues. Although experiments and models have shown a high potential for both genetic and phenotypic change in response to fishing, empirical examples of genetic responses in wild populations are rare. Here, we compare whole-genome sequence data of Atlantic cod (Gadus morhua) that were collected before (early 20th century) and after (early 21st century) periods of intensive exploitation and rapid decline in the age of maturation from two geographically distinct populations in Newfoundland, Canada, and the northeast Arctic, Norway. Our temporal, genome-wide analyses of 346,290 loci show no substantial loss of genetic diversity and high effective population sizes. Moreover, we do not find distinct signals of strong selective sweeps anywhere in the genome, although we cannot rule out the possibility of highly polygenic evolution. Our observations suggest that phenotypic change in these populations is not constrained by irreversible loss of genomic variation and thus imply that former traits could be reestablished with demographic recovery.

响应人类收获的快速进化和基因组变化的模式和程度是关键的保护问题。尽管实验和模型显示了对捕鱼的遗传和表型变化的巨大潜力，但野生种群遗传反应的经验例子很少见。在这里，我们比较了大西洋鳕鱼的全基因组序列数据（Gadus morhua) 从加拿大纽芬兰和挪威北极东北部的两个地理上不同的种群中收集到的（20 世纪初）和之后（21 世纪初）密集开发和成熟年龄迅速下降的时期。我们对 346,290 个基因座的时间、全基因组分析表明，遗传多样性和高效种群规模没有实质性损失。此外，我们在基因组的任何地方都没有发现强选择性扫描的明显信号，尽管我们不能排除高度多基因进化的可能性。我们的观察表明，这些种群的表型变化不受基因组变异不可逆转丧失的限制，因此意味着可以通过人口恢复重建以前的特征。