Keppeler Friedrich W, Winemiller Kirk O
Department of Ecology and Conservation Biology Texas A&M University College Station TX USA.
Ecol Evol. 2020 Jun 3;10(13):6562-6578. doi: 10.1002/ece3.6390. eCollection 2020 Jul.
Species interactions are difficult to quantify, and, consequently, many studies have used species traits and phylogeny as proxies under an assumption of niche conservatism (i.e., closely related and morphologically similar species should have similar niches). However, few studies have investigated whether niches actually are conserved within and across diverse communities Here, we tested the degree to which phylogenetic relatedness and morphological similarity predict diets and stable isotopic ratios ( N and C), two common descriptors of the trophic niche, in fish assemblages of two small streams in the Neotropics. We also tested the strength of the association between isotopic ratios and diet composition and found significant correlations implying that isotopic signals reveal trophic structure despite error associated with estimates of trophic enrichment and variation associated with tissue preservation, metabolism, and other factors affecting isotopic ratios. Morphological traits yielded a significant phylogenetic signal, and both morphological traits and phylogeny were correlated with diet composition, with morphological traits being a stronger predictor. We infer that functionally relevant morphological traits of fish can be used to infer trophic niches for certain kinds of questions and analyses when trophic data are lacking. However, we highlight that using phylogenetic and morphological data in combination with dietary and/or isotopic data can improve resolution of assemblage trophic structure and niche diversification.
物种间的相互作用难以量化，因此，许多研究在生态位保守性的假设下（即亲缘关系相近且形态相似的物种应具有相似的生态位），将物种特征和系统发育作为替代指标。然而，很少有研究调查生态位在不同群落内部以及不同群落之间是否真的保守。在此，我们测试了系统发育相关性和形态相似性在多大程度上能够预测新热带地区两条小河流鱼类群落的食物组成和稳定同位素比率（氮和碳），这是营养生态位的两个常见描述指标。我们还测试了同位素比率与食物组成之间关联的强度，发现了显著的相关性，这意味着尽管存在与营养富集估计相关的误差以及与组织保存、新陈代谢和其他影响同位素比率的因素相关的变化，但同位素信号仍能揭示营养结构。形态特征产生了显著的系统发育信号，并且形态特征和系统发育都与食物组成相关，其中形态特征是更强的预测指标。我们推断，当缺乏营养数据时，鱼类功能相关的形态特征可用于推断某些类型问题和分析中的营养生态位。然而，我们强调，将系统发育和形态数据与饮食和/或同位素数据结合使用，可以提高群落营养结构和生态位多样化的分辨率。
