Data from: Niche partitioning and the role of intraspecific niche variation in structuring a guild of generalist anurans

Intra-population niche differences in generalist foragers have captured the interest of ecologists, because such individuality can have important ecological and evolutionary implications. Few researchers have investigated how these differences affect the relationships among ecologically similar, sympatric species. Using stable isotopes, stomach contents, morphology and habitat preference, we examined niche partitioning within a group of five anurans and determined whether variation within species could facilitate resource partitioning. Species partitioned their niches by trophic level and by foraging habitat. However, there was considerable intraspecific variation in trophic level, with larger individuals generally feeding at higher trophic levels. For species at intermediate trophic levels, smaller individuals overlapped in trophic level with individuals of smaller species and larger individuals overlapped with the smallest individuals from larger species. Species varied in carbon isotopes; species with enriched carbon isotope ratios foraged farther from ponds, whereas species with depleted carbon isotope values foraged closer to ponds. Our study shows that these species partition their niches by feeding at different trophic levels and foraging at different distances from ponds. The intraspecific variation in trophic level decreased the number of individuals from each species that overlapped in trophic level with individuals from other species, which can facilitate species coexistence.

广食性觅食者的种群内生态位差异已引起生态学家的广泛关注，因为此类个体差异具备重要的生态学与进化学效应。目前鲜有研究者探讨此类差异如何影响生态位相似的同域分布物种（sympatric species）间的相互关系。本研究借助稳定同位素（stable isotopes）、胃容物（stomach contents）、形态学（morphology）与栖息地偏好（habitat preference）数据，对五种无尾两栖类（anurans）类群的生态位分化展开分析，并明确了物种内部的变异是否有助于资源划分（resource partitioning）。研究结果显示，这些物种通过营养级（trophic level）与觅食栖息地实现生态位分化。但种群内部存在显著的种内营养级变异：个体体型越大，其所处的营养级通常越高。对于处于中间营养级的物种而言，体型较小的个体与小型物种的个体存在营养级重叠，而体型较大的个体则与大型物种中体型最小的个体存在营养级重叠。不同物种的碳同位素（carbon isotopes）比值存在差异：碳同位素比值富集的物种觅食地点距离池塘更远，而碳同位素比值贫化的物种觅食地点则更靠近池塘。本研究表明，这些物种通过在不同营养级觅食、以及在距离池塘不同远近的区域觅食来实现生态位分化。种内营养级变异降低了各物种种群内与其他物种种群个体存在营养级重叠的个体数量，这一现象有助于物种共存。