Parallel signatures of selection in temporally-isolated lineages of pink salmon

Studying the effect of similar environments on diverse genetic backgrounds has long been a goal of evolutionary biologists with studies typically relying on experimental approaches. Pink salmon, a highly-abundant and widely-ranging salmonid, provide a naturally-occurring opportunity to study the effects of similar environments on divergent genetic backgrounds due to a strict two-year semelparous life-history. The species is composed of two reproductively-isolated lineages with overlapping ranges that share the same spawning and rearing environments in alternate years. We used restriction site-associated DNA (RAD) sequencing to discover and genotype approximately 8,000 SNP loci in three population pairs of even- and odd-year pink salmon along a latitudinal gradient in North America. We found greater differentiation within the odd-year than the even-year lineage and greater differentiation in the southern pair from Puget Sound than in the northern Alaskan population pairs. We identified 1...

长期以来，探究相似环境对多样化遗传背景的影响始终是进化生物学家的核心研究目标之一，过往相关研究多依托实验手段开展。粉鲑（pink salmon）是一类数量庞大、分布范围极广的鲑科鱼类，其严格遵循两年周期、终生仅繁殖一次的生活史。该物种包含两个生殖隔离的谱系，二者分布范围重叠，且会在交替年份共享完全一致的产卵与育幼环境，这为探究相似环境对分化型遗传背景的影响提供了天然的研究契机。本研究采用限制性酶切位点相关DNA（restriction site-associated DNA，RAD）测序技术，对北美沿纬度梯度分布的3对偶数年份与奇数年份粉鲑种群配对样本，开展了单核苷酸多态性（single nucleotide polymorphism，SNP）位点的发掘与基因分型工作，共鉴定得到约8000个SNP位点。研究结果显示，奇数年份谱系内的遗传分化程度显著高于偶数年份谱系；同时，来自普吉特湾的南部种群配对的遗传分化程度，也高于阿拉斯加北部的两组种群配对。我们共鉴定出1……