Data from: Heterospecific aggression and dominance in a guild of coral-feeding fishes: the roles of dietary ecology and phylogeny

Interspecific competition mediates biodiversity maintenance and is an important selective pressure for evolution. Competition is often conceptualized as being exploitative (indirect) or involving direct interference. However, most empirical studies are phenomenological, focusing on quantifying effects of density manipulations, and most competition theory has characterized exploitation competition systems. The effects on resource use of traits associated with direct, interference competition has received far less attention. Here we examine the relationships of dietary ecology and phylogeny to heterospecific aggression in a guild of corallivorous reef fishes. We find that, among chaetodontids (butterflyfishes), heterospecific aggression depends on a synergistic interaction of dietary overlap and specialization: aggression increases with dietary overlap for interactions between specialists but not for interactions involving generalists. Moreover, behavioral dominance is a monotonically increasing function of dietary specialization. The strong, positive relationship of dominance to specialization suggests that heterospecific aggression may contribute to the maintenance of biodiversity where it promotes resource partitioning. Additionally, we find strong phylogenetic signals in dietary overlap and specialization but not behavioral dominance. Our results support the use of phylogeny as a proxy for ecological similarity among butterflyfishes, but we find that direct measures of dietary overlap and specialization predict heterospecific agression much better than phylogeny.

种间竞争（interspecific competition）介导生物多样性维持，同时也是演化进程中的重要选择压力。竞争通常被划分为利用性竞争（exploitative competition，即间接竞争）与干扰性竞争（interference competition，即直接竞争）两类。然而，当前多数实证研究仅停留在现象描述层面，聚焦于量化密度操控（density manipulations）产生的效应，且绝大多数竞争理论均以利用性竞争系统为研究对象。与直接干扰性竞争相关的性状对资源利用的影响，至今尚未得到足够关注。本研究针对食珊瑚礁鱼类同资源种团（guild of corallivorous reef fishes），探讨了饮食生态学（dietary ecology）与系统发育（phylogeny）和异种攻击（heterospecific aggression）之间的关联。研究结果显示，在蝴蝶鱼科（Chaetodontidae）物种中，异种攻击强度取决于饮食重叠（dietary overlap）与饮食特化（dietary specialization）的协同互作：仅在特化物种间的相互作用中，攻击强度随饮食重叠程度升高而增强，而涉及广食性物种的互作则无此规律。此外，行为优势度随饮食特化程度呈单调递增关系。这种优势度与特化程度间显著的正相关关系表明，异种攻击可通过促进资源划分（resource partitioning），进而助力生物多样性维持。另外，本研究发现饮食重叠与饮食特化存在显著的系统发育信号（phylogenetic signal），但行为优势度并无此类信号。研究结果支持将系统发育作为蝴蝶鱼科物种间生态相似性的替代指标，但同时发现，直接测量的饮食重叠与特化程度，对异种攻击行为的预测效果远优于系统发育指标。