Department of Biology, Southern Arkansas University, Magnolia, USA.
Department of Biology, University of Arkansas at Little Rock, Little Rock, USA.
Oecologia. 2024 Oct;206(1-2):163-173. doi: 10.1007/s00442-024-05623-x. Epub 2024 Sep 20.
Environmental variables, such as resource quality, shape growth in organisms, dictating body size, an important correlate of fitness. Variation in prey characteristics among populations is frequently associated with similar variation in predator body sizes. Anthropogenic alterations to prey landscapes impose novel ecological pressures on predators that may shift predator phenotypes. Research has focused on determining the adaptability of the phenotypic response by testing its genetic heritability. Here, we asked if anthropogenic shifts in prey size across the landscape correlate with juvenile growth rates among populations of watersnakes with divergent life-history phenotypes. We sought to determine if growth rate variation is the product of genetic adaptation or a non-heritable phenotypic response. Using a common-garden design, we measured growth of neonate snakes from fish farms varying in prey size. We found juvenile growth rates are faster for snakes with larger initial body sizes and from populations with larger average prey sizes. Our data suggest variability in juvenile grow rates within and among populations are not the product of genetic adaptation, but the indirect consequence of initial offspring size variation and prey consumption. We propose larger offspring sizes may favor increased juvenile growth rates, mediated through a larger morphological capacity to consume and process energy resources relative to smaller individuals. This experiment provides evidence supporting the growing body of literature that non-heritable responses may be significant drivers of rapid phenotypic divergence among populations across a landscape. This mechanism may explain the stability and colonization of populations in response to rapid, human-mediated, landscape changes.
环境变量，如资源质量，塑造了生物体的生长，决定了体型，这是适应度的一个重要相关因素。种群之间猎物特征的变化通常与捕食者体型的相似变化有关。人为改变猎物的栖息地会给捕食者带来新的生态压力，从而可能改变捕食者的表型。研究集中于通过测试其遗传遗传性来确定表型反应的适应性。在这里，我们询问了景观中猎物大小的人为变化是否与具有不同生活史表型的水蛇种群的幼体生长率相关。我们试图确定生长率的变化是遗传适应性的产物还是非遗传性表型反应的产物。使用共同养殖设计，我们测量了来自猎物大小不同的鱼类养殖场的新生蛇的生长情况。我们发现，初始体型较大的蛇和平均猎物体型较大的种群的幼体生长速度较快。我们的数据表明，种群内和种群间的幼体生长速度的变异性不是遗传适应性的产物，而是初始后代大小变异和猎物消耗的间接结果。我们提出，较大的后代大小可能有利于增加幼体的生长速度，这是通过相对于较小个体更大的形态学能力来消耗和处理能量资源来介导的。这项实验提供了证据，支持了越来越多的文献，即非遗传性反应可能是景观中种群快速表型分化的重要驱动因素。这种机制可以解释种群对快速的人为景观变化的稳定性和殖民化。
