Department of Biology, University of Victoria, Victoria, BC, Canada.
Department of Natural Sciences, Biology Program, University of Alaska, Juneau, AK, United States.
Evolution. 2023 Apr 1;77(4):1101-1116. doi: 10.1093/evolut/qpad032.
The interaction between predation landscape and phenotypic variability within prey populations is of substantial significance in evolutionary biology. Extending from several decades of studies at a remote freshwater lake on Haida Gwaii, western Canada, we analyze the incidence of predator-induced sub-lethal injuries in 8,069 wild-captured threespine stickleback (Gasterosteus aculeatus) and using cohort analyses test whether the distribution of injuries informs the selective landscape influencing the bell-shaped frequency distribution of the traits. Our results indicate that (1) the incidence of injuries varies among phenotypes differing in the number and position of lateral plates, (2) these differences occur only among younger fish, (3) the incidence of injuries is inversely related to the estimated population frequencies of plate phenotypes, with the modal phenotype generally having the fewest injuries, (4) direct estimates of selective differentials and relative fitness based on analyses of 1,735 fish from 6 independent yearly cohorts indicates statistically informative elevated differentials in phenotypes with greater number of plates and elevated relative fitness of non-modal phenotypes, and (5) there are significant differences among yearly cohorts in strength and direction of selection, and an increased prevalence of diversifying versus stabilizing selection despite longer-term stasis (4 decades) in trait means. We conclude that the presence of multiple "optimal" phenotypes complements the renewed interests in quantifying short-term temporal or spatial variation in ecological processes in studies of fitness landscapes and intrapopulation variability.
捕食景观与猎物种群表型变异性之间的相互作用在进化生物学中具有重要意义。本研究扩展了加拿大西部海达瓜依偏远淡水湖中对几十年的研究，分析了 8069 只野生捕获的三刺鱼（Gasterosteus aculeatus）中捕食者诱导的亚致死伤害的发生率，并使用队列分析来检验伤害的分布是否能反映出选择性景观，从而影响这些性状的钟形频率分布。我们的结果表明：（1）损伤的发生率因侧鳍板数量和位置不同的表型而异；（2）这些差异仅发生在年轻的鱼中；（3）损伤的发生率与估计的种群中板表型的频率呈反比，其中典型表型的损伤通常最少；（4）根据对 6 个独立年度群体中 1735 条鱼的分析，直接估计选择差异和相对适合度表明，具有更多板的表型的选择差异具有统计学意义，非典型表型的相对适合度升高；（5）尽管性状均值在 4 个十年的时间里保持稳定，但年度群体之间的选择强度和方向存在显著差异，分化选择的流行度高于稳定选择。我们得出结论，存在多种“最佳”表型补充了在研究适合度景观和种群内变异性时对量化生态过程短期或空间变化的重新关注。
