Network analysis reveals contrasting effects of intraspecific competition on individual vs. population diets
Network analysis reveals contrasting effects of intraspecific competition on individual vs. population diets
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DOI：
10.1890/07-0630.1
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发表时间：
2008-07-01
期刊：
影响因子：
4.8
通讯作者：
Bolnick, Daniel I.
中科院分区：
文献类型：
--
作者：
Araujo, Marcio S.;Guimaraes, Paulo R., Jr.;Bolnick, Daniel I.
最优觅食理论预测，当种内竞争激烈，首选资源稀缺时，个体应该变得更加机会主义。这种密度依赖的饮食变化应导致增加饮食宽度的个人，因为他们添加以前未使用的猎物，他们的剧目。因此，整个种群的生态位宽度应该增加。在最近的一项研究中，R. Svanback和D. I. Bolnick证实，种内竞争导致三棘鱼（Gasterosteus aculeatus）种群饮食宽度增加。然而，个人的饮食广度并没有扩大资源水平下降。在这里，我们提出了一种基于复杂网络理论的新方法，超越了简单的饮食宽度测量，我们使用该方法重新审视刺鱼实验。该方法揭示了随着棘鱼密度的增加，种群作为一个整体增加了新的猎物类型。然而，而觅食理论预测，生态位扩张是由个人接受新的猎物，除了以前的首选猎物，我们发现，一个子集的个人停止使用他们以前的首选猎物，即使他们的人口的其他成员继续专注于原来的猎物类型。其结果是，种群被细分为生态相似的个人，群体之间的饮食变化反映了捕食行为的表型依赖性变化，猎物密度下降。这些结果与觅食理论是一致的，如果我们假设消费者之间的数量性状变化影响猎物的偏好，如果认知约束阻止个人继续使用他们以前喜欢的猎物，同时增加新的猎物。
Optimal foraging theory predicts that individuals should become more opportunistic when intraspecific competition is high and preferred resources are scarce. This density-dependent diet shift should result in increased diet breadth for individuals as they add previously unused prey to their repertoire. As a result, the niche breadth of the population as a whole should increase. In a recent study, R. Svanback and D. I. Bolnick confirmed that intraspecific competition led to increased population diet breadth in threespine stickleback (Gasterosteus aculeatus). However, individual diet breadth did not expand as resource levels declined. Here, we present a new method based on complex network theory that moves beyond a simple measure of diet breadth, and we use the method to reexamine the stickleback experiment. This method reveals that the population as a whole added new types of prey as stickleback density was increased. However, whereas foraging theory predicts that niche expansion is achieved by individuals accepting new prey in addition to previously preferred prey, we found that a subset of individuals ceased to use their previously preferred prey, even though other members of their population continued to specialize on the original prey types. As a result, populations were subdivided into groups of ecologically similar individuals, with diet variation among groups reflecting phenotype-dependent changes in foraging behavior as prey density declined. These results are consistent with foraging theory if we assume that quantitative trait variation among consumers affects prey preferences, and if cognitive constraints prevent individuals from continuing to use their formerly preferred prey while adding new prey.