A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia.
J.F. Blumenbach Institute of Zoology and Anthropology, University of Göttingen, Göttingen, Germany.
J Anim Ecol. 2021 Aug;90(8):1919-1933. doi: 10.1111/1365-2656.13511. Epub 2021 May 31.
Trophic niche differentiation may explain coexistence and shape functional roles of species. In complex natural food webs, however, trophic niche parameters depicted by single and isolated methods may simplify the multidimensional nature of consumer trophic niches, which includes feeding processes such as food choice, ingestion, digestion, assimilation and retention. Here we explore the correlation and complementarity of trophic niche parameters tackled by four complementary methodological approaches, that is, visual gut content, digestive enzyme, fatty acid and stable isotope analyses-each assessing one or few feeding processes, and demonstrate the power of method combination. Focusing on soil ecosystems, where many omnivore species with cryptic feeding habits coexist, we chose Collembola as an example. We compiled 15 key trophic niche parameters for 125 species from 40 studies. We assessed correlations among trophic niche parameters and described variation of these parameters in different Collembola species, families and across life-forms, which represent microhabitat specialisation. Correlation between trophic niche parameters was weak in 45 out of 64 pairwise comparisons, pointing at complementarity of the four methods. Jointly, the results indicated that fungal- and plant-feeding Collembola assimilate storage, rather than structural polysaccharides, and suggested bacterial feeding as a potential alternative feeding strategy. Gut content and fatty acid analyses suggested alignment between ingestion and assimilation/retention processes in fungal- and plant-feeding Collembola. From the 15 trophic niche parameters, six were related to Collembola family identity, suggesting that not all trophic niche dimensions are phylogenetically structured. Only three parameters were related to the life-forms, suggesting that species use various feeding strategies when living in the same microenvironments. Consumers can meet their nutritional needs by varying their food choices, ingestion and digestion strategies, with the connection among different feeding processes being dependent on the consumed resource and consumer adaptations. Multiple methods reveal different dimensions, together drawing a comprehensive picture of the trophic niche. Future studies applying the multidimensional trophic niche approach will allow us to trace trophic complexity and reveal niche partitioning of omnivorous species and their functional roles, especially in cryptic environments such as soils, caves, deep ocean or benthic ecosystems.
营养生态位分化可以解释物种共存和功能角色形成。然而，在复杂的自然食物网中，单一和孤立的方法所描绘的营养生态位参数可能会简化消费者营养生态位的多维性质，其中包括食物选择、摄取、消化、同化和保留等进食过程。在这里，我们通过四种互补方法探讨了营养生态位参数的相关性和互补性，即视觉肠道内容物、消化酶、脂肪酸和稳定同位素分析——每种方法都评估一个或几个进食过程，并展示了方法组合的力量。我们专注于土壤生态系统，其中许多具有隐匿性进食习惯的杂食物种共存，选择跳虫作为一个例子。我们为 40 项研究中的 125 个物种编制了 15 个关键营养生态位参数。我们评估了营养生态位参数之间的相关性，并描述了这些参数在不同跳虫物种、科和生命形式中的变化，这些变化代表了微生境的专业化。在 64 对成对比较中的 45 对中，营养生态位参数之间的相关性较弱，这表明这四种方法具有互补性。综合结果表明，真菌和植物食性跳虫同化储存物，而不是结构性多糖，并表明细菌摄食可能是一种潜在的替代摄食策略。肠道内容物和脂肪酸分析表明真菌和植物食性跳虫的摄取和同化/保留过程一致。在 15 个营养生态位参数中，有 6 个与跳虫科的身份有关，这表明并非所有营养生态位维度都具有系统发育结构。只有三个参数与生命形式有关，这表明当生活在相同的微环境中时，物种会使用各种摄食策略。消费者可以通过改变食物选择、摄取和消化策略来满足其营养需求，不同进食过程之间的联系取决于所消耗的资源和消费者的适应能力。多种方法揭示了不同的维度，共同描绘了营养生态位的全貌。未来应用多维营养生态位方法的研究将使我们能够追踪营养复杂性，并揭示杂食性物种的生态位划分及其功能角色，特别是在土壤、洞穴、深海或底栖生态系统等隐匿环境中。
