Evolution of stenophagy in spiders (Araneae): evidence based on the comparative analysis of spider diets

Stenophagy (narrow diet breadth) represents an extreme of trophic specialization in carnivores, but little is known about the forces driving its evolution. We used spiders, the most diversified group of terrestrial predators, to investigate whether stenophagy 1) promoted diversification, 2) was phylogenetically conserved and evolutionarily derived state, and 3) was determined either by geographical distribution and foraging guild. We utilized published data on the prey of almost 600 species. Six categories of stenophagy were found: myrmecophagy, araneophagy, lepidopterophagy, termitophagy, dipterophagy and crustaceophagy. We found that the species diversity of euryphagous genera and families was similar to stenophagous genera and families. At the family level, stenophagy evolved repeatedly and independently. Within families, the basal condition was oligophagy or euryphagy. Most types of stenophagy were clearly derived: myrmecophagy in Zodariidae; lepidopterophagy in Araneidae; dipteroph...狭食性（stenophagy）指食幅狭窄，是食肉动物营养特化的极端表现形式，但目前学界对驱动其演化的潜在机制仍知之甚少。本研究以陆生捕食类群中物种多样性最高的蜘蛛为研究对象，旨在探究狭食性是否具备以下特征：1）可推动物种演化多样化；2）具有系统发育保守性且属于演化衍生状态；3）由地理分布与觅食功能群（foraging guild）决定。本研究使用了已发表的近600个蜘蛛物种的猎物捕食数据，共识别出6类狭食性类型：蚁食性（myrmecophagy）、蛛食性（araneophagy）、鳞翅目食性（lepidopterophagy）、白蚁食性（termitophagy）、双翅目食性（dipterophagy）以及甲壳动物食性（crustaceophagy）。研究发现，广食性（euryphagy）属与科的物种多样性与狭食性类群并无显著差异。在科分类阶元上，狭食性经历了多次独立的演化起源。在科内，祖先类群的食性通常为寡食性（oligophagy）或广食性。多数狭食性类型均为明确的演化衍生状态：如Zodariidae的蚁食性、Araneidae的鳞翅目食性、双翅目食性……