Data from: Testing for local adaptation to spawning habitat in sympatric subpopulations of pike by reciprocal translocation of embryos

We tested for local adaption in early life-history traits by performing a reciprocal translocation experiment with approximately 2,500 embryos of pike (Esox lucius) divided in paired split-family batches. The experiment indicated local adaptation in one of the two subpopulations manifested as enhanced hatching success of eggs in the native habitat, both when compared to siblings transferred to a non-native habitat, and when compared to immigrant genotypes from the other subpopulation. Gene-by-environment effects on viability of eggs and larvae were evident in both subpopulations, showing that there existed genetic variation allowing for evolutionary responses to divergent selection, and indicating a capacity for plastic responses to environmental change. Next, we tested for differences in female life-history traits. Results uncovered that females from one population invested more resources into reproduction and also produced more (but smaller) eggs in relation to their body size compared to females from the other population. We suggest that these females have adjusted their reproductive strategies as a counter-adaptation because a high amount of sedimentation on the eggs in that subpopulations spawning habitat might benefit smaller eggs. Collectively, our findings point to adaptive divergence among sympatric subpopulations that are physically separated only for a short period during reproduction and early development—which is rare. These results illustrate how combinations of translocation experiments and field studies of life-history traits might infer about local adaptation and evolutionary divergence among populations. Local adaptations in subdivided populations are important to consider in management and conservation of biodiversity, because they may otherwise be negatively affected by harvesting, supplementation, and reintroduction efforts targeted at endangered populations.

本研究以约2500枚白斑狗鱼（*Esox lucius*）胚胎为实验材料，将其按配对拆分家系分组，通过相互易地移植实验验证早期生活史性状（early life-history traits）的本地适应性（local adaption）。实验结果显示，两个亚种群中的其中一个存在本地适应性：相较于被转移至非原生境的同胞胚胎，以及来自另一亚种群的迁入基因型胚胎，该亚种群的卵在原生境中的孵化成功率显著更高。两个亚种群中均观察到基因-环境互作效应（gene-by-environment effects）对卵和幼体存活力的显著影响，这表明种群中存在可响应歧化选择（divergent selection）的遗传变异，同时也证明种群具备对环境变化做出塑性响应（plastic responses）的能力。随后，本研究检测了雌性个体的生活史性状差异。结果发现，相较于另一种群的雌性个体，某一种群的雌性个体在繁殖上投入的资源更多，且相对于自身体型而言，其产卵量更高（但卵粒更小）。我们推测，该种群雌性的繁殖策略已通过反适应（counter-adaptation）进行了调整，原因在于该亚种群产卵生境中卵表面的大量沉积物可能更利于小型卵粒存活。综合来看，本研究结果证实了同域分布亚种群（sympatric subpopulations）间存在适应性分化——这类亚种群仅在繁殖和早期发育阶段存在短暂的物理隔离，此类案例较为罕见。本研究结果阐明了，结合易地移植实验与生活史性状野外研究，可如何推断种群间的本地适应性与进化分化模式。在生物多样性管理与保护工作中，需重点关注具有亚种群结构的种群的本地适应性：若忽视这一点，针对濒危种群的捕捞、补充放养及再引入措施可能会对其产生负面影响。