title: Evidence for cryptic speciation in directly transmitted gyrodactylid parasites of Trinidadian guppies.
abstract: Cryptic species complexes are common among parasites, which tend to have large populations and are subject to rapid evolution. Such complexes may arise through host-parasite co-evolution and/or host switching. For parasites that reproduce directly on their host, there might be increased opportunities for sympatric speciation, either by exploiting different hosts or different micro-habitats within the same host. The genus Gyrodactylus is a specious group of viviparous monogeneans. These ectoparasites transfer between teleosts during social contact and cause significant host mortality. Their impact on the guppy (Poecilia reticulata), an iconic evolutionary and ecological model species, is well established and yet the population genetics and phylogenetics of these parasites remains understudied. Using mtDNA sequencing of the host and its parasites, we provide evidence of cryptic speciation in Gyrodactylus bullatarudis, G. poeciliae and G. turnbulli. For the COII gene, genetic divergence of lineages within each parasite species ranged between 5.7 and 17.2%, which is typical of the divergence observed between described species in this genus. Different lineages of G. turnbulli and G. poeciliae appear geographically isolated, which could imply allopatric speciation. In addition, for G. poeciliae, co-evolution with a different host species cannot be discarded due to its host range. This parasite was originally described on P. caucana, but for the first time here it is also recorded on the guppy. The two cryptic lineages of G. bullatarudis showed considerable geographic overlap. G. bullatarudis has a known wide host range and it can also utilize a killifish (Anablepsoides hartii) as a temporary host. This killifish is capable of migrating overland and it could act as a transmission vector between otherwise isolated populations. Additional genetic markers are needed to confirm the presence of these cryptic Gyrodactylus species complexes, potentially leading to more in-depth genetic, ecological and evolutionary analyses on this multi-host-parasite system.
authors.affiliation: School of Biological Sciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom; CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Xavier
authors.affiliation: School of Biological Sciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom.
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Faria
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Paladini
authors.affiliation: School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom.
authors.forename: Cock
authors.initials: C
authors.lastname: van Oosterhout
authors.affiliation: School of Biological Sciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom.
authors.forename: Mireille
authors.initials: M
authors.lastname: Johnson
authors.affiliation: School of Biological Sciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom.
authors.forename: Jo
authors.initials: J
authors.lastname: Cable
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D049810:Genetic Speciation; D006239:Haplotypes; D058507:Host Specificity; D006790:Host-Parasite Interactions; D008969:Molecular Sequence Data; D010802:Phylogeny; D010986:Platyhelminths / Q000145:classification* / Q000235:genetics*; D011036:Poecilia / Q000145:classification / Q000235:genetics* / Q000469:parasitology*; D017422:Sequence Analysis, DNA
chemical_list: D004247:DNA