Predicting community outcomes from pairwise interactions: integrating density- and trait-mediated effects
Predicting community outcomes from pairwise interactions: integrating density- and trait-mediated effects
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DOI：
10.1007/s00442-002-0910-z
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发表时间：
2002-05-01
期刊：
影响因子：
2.7
通讯作者：
Yurewicz, KL
中科院分区：
文献类型：
--
作者：
Relyea, RA;Yurewicz, KL
对生态学家来说，理解基于两两比较的物种相互作用是如何塑造生态群落结构的是一项艰巨的任务，因为重新组合的群落的影响可能与简单的密度介导的相互作用所暗示的不同。这种复杂性的部分原因是，许多物种在面对不同的捕食者和竞争对手时改变了它们的行为和形态，从而改变了它们的人均相互作用率（即性状介导的相互作用）。我们的目标是利用一个由两种捕食者（蜻蜓幼虫和蝾螈幼虫）、两种猎物（绿蛙幼虫和牛蛙幼虫）和一个共享的猎物资源组成的简单实验群落，来确定我们是否可以通过结合我们对密度和特征介导的相互作用的了解来预测重新组合的群落中的相互作用。我们将捕食率和捕食者诱导行为的两两实验室实验与中观实验相结合，以检验密度和性状介导的效应。我们采用了无捕食者、笼养Anax（在不改变猎物密度的情况下诱导抗捕食者性状）和与无捕食者、笼养Ambystoma和致死Amkystoina杂交的致命Anax的因子组合。基于两两实验，对重组群落中物种间的相互作用进行了定性预测。致命的Anax捕食Ambystoma和绿蛙，而致命的Ambystoma只捕食绿蛙。Anax还减少了绿蛙的活动；这导致蝾螈对绿蛙的捕食减少，绿蛙对资源的获取减少，牛蛙对资源的获取增加。壶口对绿蛙的活动没有影响，对绿蛙的资源获取没有影响，对牛蛙的资源获取没有影响。这些结果表明，如果我们对性状介导机制有更详细的了解，我们可以更好地了解物种在自然群落中的相互作用。然而，如果预测大型群落的结构需要确定每个物种如何在所有其他物种存在的情况下改变其特征以及改变密度，那么提高我们的预测能力可能是一项艰巨的任务。
Understanding how species interactions shape the structure of ecological communities based on pairwise comparisons has been a difficult undertaking for ecologists because effects in reassembled communities can be different than simple density-mediated interactions would suggest. Part of this complexity occurs because many species change their behavior and morphology with different predators and competitors and, thus, change their per-capita interaction rates (i.e. trait-mediated interactions). Our objective was to use a simple experimental community of two predators (larval dragonflies, Anax longipes, and larval salamanders, Ambystoma tigrinum), two prey (larval green frogs, Rana clamitans, and larval bullfrogs, R. catesbeiana), and a shared prey resource to determine whether we can predict interactions in a reassembled community by combining our knowledge of density- and trait-mediated interactions,. We combined pairwise laboratory experiments on predation rates and predator-induced behaviors with a mesocosm experiment to examine density- and trait-mediated effects. We used a factorial combination of no predators, caged Anax (to induce anti-predator traits without changing prey density), and lethal Anax crossed with no predators, caged Ambystoma, and lethal Amkystoina. The species interactions in the reassembled community were qualitatively predictable based on the pairwise experiments. Lethal Anax preyed upon Ambystoma and green frogs while lethal Ambystoma only preyed upon green frogs. Anax also reduced the activity of the green frogs; this caused a decrease in salamander predation on green frogs, a decrease in green frog acquisition of resources, and an increase in bullfrog acquisition of resources. Ambystoma had no effect on green frog activity, no effect on resource acquisition by green frogs, and no effect on resource acquisition by bullfrogs. These results suggest that we can better understand how species interact in natural communities if we have a more detailed understanding of trait-mediated mechanisms. However, if predicting the structure of large communities requires identifying how each species alters its traits in the presence of all other species along with altering density, improving our predictive ability may be a prohibitively large undertaking.