Cloyed Carl S, Eason Perri K
National Great Rivers Research and Education Center, East Alton, IL 62024, USA; Department of Biology, Washington University in St Louis, St Louis, MO 63130, USA.
Department of Biology , University of Louisville , Louisville, KY 40292 , USA.
R Soc Open Sci. 2017 Mar 15;4(3):170060. doi: 10.1098/rsos.170060. eCollection 2017 Mar.
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.
广食性觅食者种群内部的生态位差异引起了生态学家的兴趣，因为这种个体差异可能具有重要的生态和进化意义。很少有研究人员调查这些差异如何影响生态相似的同域物种之间的关系。我们使用稳定同位素、胃内容物、形态学和栖息地偏好，研究了一组五种蛙类的生态位划分，并确定物种内的变异是否有助于资源分配。物种通过营养级和觅食栖息地来划分它们的生态位。然而，营养级存在相当大的种内变异，较大个体通常在较高营养级觅食。对于处于中等营养级的物种，较小个体在营养级上与较小物种的个体重叠，而较大个体与较大物种中最小的个体重叠。物种在碳同位素方面存在差异；碳同位素比率富集的物种在离池塘较远的地方觅食，而碳同位素值贫化的物种在离池塘较近的地方觅食。我们的研究表明，这些物种通过在不同营养级觅食和在离池塘不同距离处觅食来划分它们的生态位。营养级的种内变异减少了每个物种中与其他物种个体在营养级上重叠的个体数量，这有助于物种共存。
