Davenport Jon M, Babineau Alan M, Sloan Reese K, Groesbeck Autumn, Montazeri Ali J, Ramey Maxwell
Department of Biology, Appalachian State University, Boone, North Carolina, USA.
Ecology. 2025 Jan;106(1):e4530. doi: 10.1002/ecy.4530.
The importance of trait variation has long been recognized in ecological and evolutionary research. The divergence of sexually dimorphic traits (e.g., body size, morphology, behavior, etc.) is primarily attributed to sexual selection, and sexual dimorphism can have consequences for diets and habitat use. Recent evidence for one aquatic predator species (adult newts; Notophthalmus viridescens) suggests that trait differences and habitat partitioning between the sexes may be important in structuring zooplankton communities. However, newts are known to increase amphibian diversity within pond communities via keystone predation. Yet, no data are available on differentiating potentially sexually dimorphic effects of newts on larval amphibian communities. Thus, we conducted a series of mesocosm experiments to determine the effects of sexual dimorphism of adult newts on larval amphibian communities. Based on previous work with newts and zooplankton, we hypothesized that male and female newts would have differing effects on prey communities. We found that female newts consumed one prey species more than male newts did and no newt treatments. There were no differences between the sexes in prey consumption of another prey species. Size at metamorphosis was greater in the presence of newts (either male or female) for wood frogs and in the presence of female newts for spotted salamanders in comparison with no newt treatments. Our findings indicate that sexual dimorphism within a known keystone predator can have differential effects on prey. Indeed, our results indicate that while the effects of predators on one response (survival) can differ between sexes, the impacts on another response (prey fitness; measured as size at metamorphosis) were similar. Our research to understand the effects of sexual dimorphism is timely as sex ratios of predators may become skewed in nature due to anthropogenic change. If intraspecific differences exist via top-down effects, then downstream impacts on prey communities may go unnoticed.
性状变异的重要性在生态学和进化研究中早已得到认可。两性异形性状（如体型、形态、行为等）的差异主要归因于性选择，而两性异形可能会对饮食和栖息地利用产生影响。最近关于一种水生捕食者物种（成年蝾螈；绿红东美螈）的证据表明，两性之间的性状差异和栖息地划分可能在构建浮游动物群落中起着重要作用。然而，蝾螈通过关键捕食作用增加了池塘群落中的两栖动物多样性。然而，目前尚无关于区分蝾螈对幼体两栖动物群落潜在两性异形影响的数据。因此，我们进行了一系列中宇宙实验，以确定成年蝾螈的两性异形对幼体两栖动物群落的影响。基于之前对蝾螈和浮游动物的研究，我们假设雄性和雌性蝾螈对猎物群落的影响会有所不同。我们发现雌性蝾螈比雄性蝾螈多捕食一种猎物，且不存在无蝾螈处理的情况。在另一种猎物的捕食量上，两性之间没有差异。与无蝾螈处理相比，在有蝾螈（雄性或雌性）存在的情况下，林蛙的变态时体型更大，在有雌性蝾螈存在的情况下，黄斑蝾螈的变态时体型更大。我们的研究结果表明，已知的关键捕食者内部的两性异形可能对猎物产生不同的影响。事实上，我们的结果表明，虽然捕食者对一种反应（生存）的影响在两性之间可能不同，但对另一种反应（猎物适合度；以变态时的体型衡量）的影响是相似的。我们旨在了解两性异形影响的研究很及时，因为由于人为变化，捕食者的性别比例在自然界中可能会失衡。如果通过自上而下的效应存在种内差异，那么对猎物群落的下游影响可能会被忽视。
