Phoretic Poecilochirus mites specialise on their burying beetle hosts

Recurring species interactions can cause species to adapt to each other. Specialization will increase the fitness of symbionts in the coevolved association but may reduce the flexibility of symbiont choice as it will often decrease fitness in interactions with other than the main symbiont species. We analyzed the fitness interactions between a complex of two cryptic mite species and their sympatric burying beetle hosts in a European population. Poecilochirus mites (Mesostigmata, Parasitidae) are phoretic on burying beetles and reproduce alongside beetles, while these care for their offspring at vertebrate carcasses. While Poecilochirus carabi is typically found on Nicrophorus vespilloides beetles, P. necrophori is associated with N. vespillo. It has long been known that the mites discriminate between the two beetle species, but the fitness consequences of this choice remained unknown. We experimentally associated both mite species with both beetle species and found that mite fitness suf...反复发生的物种间相互作用可促使物种间产生相互适应。宿主选择特化可提升共生体（symbiont）在共进化关联中的适合度（fitness），但会降低共生体的宿主选择灵活性——因为相较于主要宿主物种，与其他宿主物种互动时，共生体的适合度往往会下降。我们针对欧洲种群中的两种隐蔽螨类及其同域分布的埋葬甲宿主之间的适合度相互作用展开了研究。寄螨属（Poecilochirus）螨类（隶属于中气门亚目Mesostigmata、寄螨科Parasitidae）以埋葬甲为携播（phoretic）宿主，并与埋葬甲同步繁殖；埋葬甲会在脊椎动物尸体上抚育自身后代。通常穴居寄螨（Poecilochirus carabi）仅见于埋葬甲（Nicrophorus vespilloides）体表，而尸食寄螨（P. necrophori）则与埋葬甲（N. vespillo）形成稳定关联。长期以来学界已知该类螨类可区分两种埋葬甲物种，但该宿主选择行为所带来的适合度后果却始终未被探明。我们通过实验将两种螨类分别与两种埋葬甲进行配对，并发现螨类的适合度会出现显著下降（原文后续内容截断）。