Host-parasite interactions in perpetual darkness: Macroparasite diversity in the cavefish <i>Astyanax mexicanus</i>
Ana Santacruz, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, México City CP 04510, México, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, México City CP 04510, México, David I. Hernández-Mena, Ramsés Miranda‐Gamboa, Gerardo Pérez‐Ponce de León, Claudia Patricia Ornelas‐García, Departamento de Sistemas y Procesos Naturales, Escuela Nacional de Estudios Superiores Unidad Mérida, Ucú, Yucatán CP 97357, México, Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos CP 62580, México, Colección Nacional de Peces, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, México City CP 04510, México, Departamento de Sistemas y Procesos Naturales, Escuela Nacional de Estudios Superiores Unidad Mérida, Ucú, Yucatán CP 97357, México, Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos CP 62580, México, Colección Nacional de Peces, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, México City CP 04510, México
Abstract
<i>Astyanax mexicanus</i> 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 <i>A. mexicanus</i> 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.