Mechanisms of individual variation in large herbivore diets: Roles of spatial heterogeneity and state-dependent foraging.
Mechanisms of individual variation in large herbivore diets: Roles of spatial heterogeneity and state-dependent foraging.
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许多消费者群体由相对专业的个体组成，他们只吃大众消费的食物的一部分。尽管个体水平饮食差异的生态意义已得到认可，但这种差异很难记录，其潜在机制也知之甚少。最佳觅食理论为预测个体如何选择不同的饮食提供了一个有用的框架，该理论假设动物会平衡停止吃现有食物的“机会成本”与寻找更有营养的食物的成本；饮食结构应取决于食物的分配，当个体觅食者有更多的能量储备来投资寻找高质量食物时，他们应该更有选择性。我们通过量化非洲洪泛区稀树草原生态系统中广泛吃食的羚羊（bushbuck，Tragelaphus sylvaticus）饮食的环境（资源异质性）和有机（营养状况）决定因素，测试了个体生态位分化的预测机制。我们使用从 15 只佩戴 GPS 项圈的动物（每只动物 6-14 个样本，中位数 12）中重复收集的粪便样本进行 DNA 元条形码编码，量化了个体实现的饮食生态位（分类丰富度和组成）。羚羊的饮食结构是由空间异质性构成的，并受到个体条件的限制。我们观察到两种相邻栖息地类型（洪泛区和林地）内部和之间的羚羊对食用植物的显着个体水平划分。居住范围更近和/或具有相似植被结构（使用激光雷达测量）的个体饮食更相似，支持异质资源分布促进个体分化的预测。与营养状况不佳的个体相比，营养状况良好的个体的饮食范围明显更窄（植物类群更少），更密集地搜索它们的栖息地（使用强度指数），并且饮食质量更高（可消化蛋白质百分比），这支持了这样的预测：内源储备更大的动物的实现利基范围更窄，因为它们可以投入更多时间来寻找营养食物。我们的结果支持了最佳觅食理论关于个体水平饮食变化的能量基础的预测，并提供了一个潜在的通用框架，用于理解个体实现的生态位宽度如何受到异质景观中动物行为和生理学的控制。
Many populations of consumers consist of relatively specialized individuals that eat only a subset of the foods consumed by the population at large. Although the ecological significance of individual‐level diet variation is recognized, such variation is difficult to document, and its underlying mechanisms are poorly understood. Optimal foraging theory provides a useful framework for predicting how individuals might select different diets, positing that animals balance the “opportunity cost” of stopping to eat an available food item against the cost of searching for something more nutritious; diet composition should be contingent on the distribution of food, and individual foragers should be more selective when they have greater energy reserves to invest in searching for high‐quality foods. We tested these predicted mechanisms of individual niche differentiation by quantifying environmental (resource heterogeneity) and organismal (nutritional condition) determinants of diet in a widespread browsing antelope (bushbuck, Tragelaphus sylvaticus) in an African floodplain‐savanna ecosystem. We quantified individuals' realized dietary niches (taxonomic richness and composition) using DNA metabarcoding of fecal samples collected repeatedly from 15 GPS‐collared animals (range 6–14 samples per individual, median 12). Bushbuck diets were structured by spatial heterogeneity and constrained by individual condition. We observed significant individual‐level partitioning of food plants by bushbuck both within and between two adjacent habitat types (floodplain and woodland). Individuals with home ranges that were closer together and/or had similar vegetation structure (measured using LiDAR) ate more similar diets, supporting the prediction that heterogeneous resource distribution promotes individual differentiation. Individuals in good nutritional condition had significantly narrower diets (fewer plant taxa), searched their home ranges more intensively (intensity‐of‐use index), and had higher‐quality diets (percent digestible protein) than those in poor condition, supporting the prediction that animals with greater endogenous reserves have narrower realized niches because they can invest more time in searching for nutritious foods. Our results support predictions from optimal foraging theory about the energetic basis of individual‐level dietary variation and provide a potentially generalizable framework for understanding how individuals' realized niche width is governed by animal behavior and physiology in heterogeneous landscapes.
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影响因子：
2.3
作者：
Cook, Rachel C.;Cook, John G.;Miller, Patrick J.
通讯作者：
Miller, Patrick J.
影响因子：
4.9
作者：
Deagle BE;Thomas AC;McInnes JC;Clarke LJ;Vesterinen EJ;Clare EL;Kartzinel TR;Eveson JP
通讯作者：
Eveson JP
DOI：
10.1590/s1984-46702010000500002
发表时间：
2010-10-01
期刊：
Zoologia (Curitiba)
影响因子：
--
作者：
Almeida, Paulo J. A. L.;Vieira, Marcus V.;Cerqueira, Rui
通讯作者：
Cerqueira, Rui
影响因子：
2.9
作者：
EMLEN, JM
通讯作者：
EMLEN, JM
影响因子：
16.6
作者：
Carlson BS;Rotics S;Nathan R;Wikelski M;Jetz W
通讯作者：
Jetz W