Intraspecific trait variation in generalist animals is widespread in nature, yet its effects on community ecology are not well understood. Newts are considered opportunistic feeders that may co-occur in different syntopic conditions and represent an excellent model for studying the role of individual feeding specialization in shaping the population dietary strategy. Here, we investigated the diet of three newt species from central Italy occurring in artificial habitats in different coexistence conditions to test the predictions of the niche width (NW) variation hypotheses. Population NW did not vary among species and between presence and absence of coexisting species. An overall positive relationship between individual specialization and population NW was observed. However, this pattern was disrupted by the condition of syntopy with newt populations showing an individual NW variation invariant with population NW in presence of coexisting species, whereas it was larger in populations occurring alone. The observed pattern of newt behavior was not consistent with any of the proposed scenarios. We found a consistent pattern with the degree of individual specialization being (1) size-dependent (specialized individuals increasing within larger sized species) and (2) assemblage-complexity-dependent (specialized individuals increasing in syntopic populations in comparison to singly populations).

中文翻译：

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跨条件条件下共生New物种的饲养策略：“种群内生态位变异”假说的检验

通才动物中的种内性状变异在自然界很普遍，但是对社区生态的影响尚不十分清楚。ts被认为是机会饲养者，可能在不同的条件下同时出现，并且代表了研究个体喂养专业化在制定种群饮食策略中的作用的极好的模型。在这里，我们调查了来自意大利中部的三种new物种在不同共存条件下的人工栖息地中的饮食，以测试生态位宽度（NW）变异假说的预测。不同物种之间以及存在和不存在共存物种之间的种群净重均没有变化。观察到个体专业化与人口西北地区之间的总体正相关关系。然而，这种模式被与with种群同位的条件所破坏，new种群在并存物种存在下个体净重变异随种群净重不变，而在单独发生的种群中则更大。观察到的of行为模式与所提出的任何方案均不一致。我们发现一个一致的模式，即个体专业化程度是（1）大小依赖性（大型个体内较大的特殊个体）和（2）组装复杂度依赖性（与单个种群相比，复合种群中的特殊个体）。观察到的of行为模式与所提出的任何方案均不一致。我们发现一个一致的模式，即个体专业化程度是（1）大小依赖性（大型个体内较大的特殊个体）和（2）组装复杂度依赖性（与单个种群相比，复合种群中的特殊个体）。观察到的of行为模式与所提出的任何方案均不一致。我们发现一个一致的模式，即个体专业化程度是（1）大小依赖性（大型个体内较大的特殊个体）和（2）组装复杂度依赖性（与单个种群相比，复合种群中的特殊个体）。