Evolutionary divergence of adult body size and juvenile growth in sympatric subpopulations of a top predator in aquatic ecosystems

Evolutionary theory predicts that different selective regimes may contribute to divergent evolution of body size and growth rate among populations, but most studies have focused on allopatric populations. Here, we studied five sympatric subpopulations of anadromous northern pike (Esox lucius) in the Baltic Sea subjected to allopatric habitats for a short period of their life cycle due to homing behavior. We report differences in adult body size among subpopulations that were in part due to variation in growth rate. Body size of emigrating juveniles also differed among subpopulations, and differences remained when individuals were reared in a common environment, thus indicating evolutionary divergence among subpopulations. Furthermore, a QST-FST comparison indicated that differences had evolved due to divergent selection rather than genetic drift, possibly in response to differences in selective mortality among spawning habitats during the allopatric life stage. Adult and juvenile size w...

进化论预测，不同的选择机制（selective regime）可能会导致不同种群在体型与生长速率上产生趋异演化，但现有多数研究均聚焦于异域种群（allopatric population）。本研究针对波罗的海海域内5个溯河洄游型白斑狗鱼（Esox lucius）的同域亚种群（sympatric subpopulation）展开分析：由于归巢行为（homing behavior），这些亚种群的个体在生命周期的短暂阶段会经历异域栖息环境。研究发现，不同亚种群间的成体体型存在差异，该差异部分源于生长速率的变异；洄游幼体的体型在各亚种群间同样存在差异，将个体置于共同环境（common environment）中饲养时，该差异依然存在，这表明各亚种群间已发生演化趋异。此外，QST-FST比对（QST-FST comparison）结果显示，亚种群间的体型差异是由趋异选择（divergent selection）而非遗传漂变（genetic drift）演化而来，这或是对异域生活阶段中不同产卵栖息地间选择死亡率差异的适应。成体与幼体体型……