Allgeier Jacob E, Adam Thomas C, Burkepile Deron E
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
Marine Science Institute, University of California, Santa Barbara, Santa Barbara, CA, USA.
Proc Biol Sci. 2017 Jun 14;284(1856). doi: 10.1098/rspb.2017.0307.
Resolving how species compete and coexist within ecological communities represents a long-standing challenge in ecology. Research efforts have focused on two predominant mechanisms of species coexistence: complementarity and redundancy. But findings also support an alternative hypothesis that within-species variation may be critical for coexistence. Our study focuses on nine closely related and ecologically similar coral reef fish species to test the importance of individual- versus species-level traits in determining the size of dietary, foraging substrate, and behavioural interaction niches. Specifically, we asked: (i) what level of biological organization best describes individual-level niches? and (ii) how are herbivore community niches partitioned among species, and are niche widths driven by species- or individual-level traits? Dietary and foraging substrate niche widths were best described by species identity, but no level of taxonomy explained behavioural interactions. All three niches were dominated by only a few species, contrasting expectations of niche complementarity. Species- and individual-level traits strongly drove foraging substrate and behavioural niches, respectively, whereas the dietary niche was described by both. Our findings underscored the importance of species-level traits for community-level niches, but highlight that individual-level trait variation within a select few species may be a key driver of the overall size of niches.
解析物种如何在生态群落中竞争与共存是生态学中一个长期存在的挑战。研究工作主要集中在物种共存的两种主要机制：互补性和冗余性。但研究结果也支持另一种假说，即物种内变异可能对共存至关重要。我们的研究聚焦于9种亲缘关系密切且生态习性相似的珊瑚礁鱼类，以测试个体水平与物种水平的性状在决定食性、觅食基质及行为相互作用生态位大小方面的重要性。具体而言，我们提出以下问题：（i）何种生物组织水平能最好地描述个体水平的生态位？以及（ii）草食动物群落生态位在物种间是如何划分的，生态位宽度是由物种水平还是个体水平的性状驱动？食性和觅食基质生态位宽度最好由物种身份来描述，但没有任何分类学水平能解释行为相互作用。所有这三种生态位都仅由少数物种主导，这与生态位互补性的预期相反。物种水平和个体水平的性状分别强烈驱动觅食基质和行为生态位，而食性生态位则由两者共同描述。我们的研究结果强调了物种水平性状对群落水平生态位的重要性，但也突出表明，少数物种内的个体水平性状变异可能是生态位总体大小的关键驱动因素。
