Astyanax mexicanus has repeatedly colonized cave environments, displaying evolutionary parallelisms in many troglobitic traits. Despite being a model system for the study of adaptation to life in perpetual darkness, the parasites that infect cavefish are practically unknown. In this study, we investigated the macroparasite communities in 18 cavefish populations from independent lineages and compared them with the parasite diversity found in their sister surface fish populations, with the aim of better understanding the role that parasites play in the colonization of new environments. Within the cavefish populations, we identified 13 parasite taxa, including a subset of 10 of the 27 parasite taxa known for the surface populations. Parasites infecting the cavefish belong to five taxonomic groups, including trematodes, monogeneans, nematodes, copepods, and acari. Monogeneans are the most dominant group, found in 14 caves. The macroparasites include species with direct life cycles and trophic transmission, including invasive species. Surprisingly, paired comparisons indicate higher parasite richness in the cavefish than in the surface fish. Spatial variation in parasite composition across the caves suggests historical and geographical contingencies in the host-parasite colonization process and potential evolution of local adaptations. This base-line data on parasite diversity in cavefish populations of A. mexicanus provides a foundation to explore the role of divergent parasite infections under contrasting ecological pressures (cave vs. surface environments) in the evolution of cave adaptive traits.
墨西哥脂鲤多次在洞穴环境中定居，在许多穴居性状上表现出进化的相似性。尽管洞穴鱼是研究适应永久黑暗生活的模式系统，但目前对感染洞穴鱼的寄生虫知之甚少。为更好地了解寄生虫在宿主适应新环境过程中所起的作用，该研究调查了18个独立谱系的洞穴鱼种群的大型寄生虫群落，并将它们与在其姐妹表层鱼类种群中发现的寄生虫多样性进行了比较。在洞穴鱼种群中，我们发现了13个寄生虫类群，包括已知的表层种群27个寄生虫类群中10个类群的子集。感染洞穴鱼的寄生虫可分为五类：吸虫、单殖吸虫、线虫、桡足类和蜱螨。共在14个洞穴中发现了单殖吸虫，是最主要的类群。大型寄生虫包括具有直接生命周期和营养传播的物种，包含入侵物种。令人惊讶的是，配对比较表明洞穴鱼的寄生虫丰富度高于表层鱼类。洞穴种群间间寄生虫组成的空间变化表明宿主-寄生虫适应新环境过程中的历史和地理偶然性以及当地适应的潜在进化。该研究为探讨不同生态压力(洞穴与地表环境)下不同寄生虫感染在洞穴适应性状进化中的作用提供了基础。.
Keywords: Adaptation; Metazoan parasites; Niche change; Parasite assemblage; Prevalence.