title: Genetic population structure of Gyrodactylus thymalli (Monogenea) in a large Norwegian river system.
abstract: The extent of geographic genetic variation is the result of several processes such as mutation, gene flow, selection and drift. Processes that structure the populations of parasite species are often directly linked to the processes that influence the host. Here, we investigate the genetic population structure of the ectoparasite Gyrodactylus thymalli Žitňan, 1960 (Monogenea) collected from grayling (Thymallus thymallus L.) throughout the river Glomma, the largest watercourse in Norway. Parts of the mitochondrial dehydrogenase subunit 5 (NADH 5) and cytochrome oxidase I (COI) genes from 309 G. thymalli were analysed to study the genetic variation and investigated the geographical distribution of parasite haplotypes. Three main clusters of haplotypes dominated the three distinct geographic parts of the river system; one cluster dominated in the western main stem of the river, one in the eastern and one in the lower part. There was a positive correlation between pairwise genetic distance and hydrographic distance. The results indicate restricted gene flow between sub-populations of G. thymalli, most likely due to barriers that limit upstream migration of infected grayling. More than 80% of the populations had private haplotypes, also indicating long-time isolation of sub-populations. According to a molecular clock calibration, much of the haplotype diversity of G. thymalli in the river Glomma has developed after the last glaciation.
authors.affiliation: Department of Biosciences,Center for Ecological and Evolutionary Synthesis,University of Oslo,P. O. Box 1066 Blindern,0316 Oslo,Norway.
authors.forename: Ruben Alexander
authors.initials: RA
authors.lastname: Pettersen
authors.affiliation: Norwegian Veterinary Institute,P.O. Box 750 Sentrum,0106 Oslo,Norway.
authors.forename: Tor Atle
authors.initials: TA
authors.lastname: Mo
authors.affiliation: Norwegian Veterinary Institute,P.O. Box 750 Sentrum,0106 Oslo,Norway.
authors.forename: Haakon
authors.initials: H
authors.lastname: Hansen
authors.affiliation: Department of Biosciences,Center for Ecological and Evolutionary Synthesis,University of Oslo,P. O. Box 1066 Blindern,0316 Oslo,Norway.
authors.forename: Leif Asbjørn
authors.initials: LA
authors.lastname: Vøllestad
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D025041:Animal Migration / Q000502:physiology; D000818:Animals; D016000:Cluster Analysis; D018509:DNA, Helminth / Q000737:chemistry / Q000302:isolation & purification; D004272:DNA, Mitochondrial / Q000737:chemistry; D004478:Ectoparasitic Infestations / Q000469:parasitology / Q000662:veterinary*; D003576:Electron Transport Complex IV / Q000235:genetics; D005393:Fish Diseases / Q000469:parasitology*; D051456:Gene Flow; D014644:Genetic Variation; D006239:Haplotypes; D015999:Multivariate Analysis; D009243:NAD / Q000235:genetics; D009664:Norway; D010802:Phylogeny; D010986:Platyhelminths / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D011157:Population Dynamics; D045483:Rivers / Q000469:parasitology*; D012487:Salmonidae / Q000469:parasitology*
chemical_list: D018509:DNA, Helminth; D004272:DNA, Mitochondrial; D009243:NAD; D003576:Electron Transport Complex IV
keywords: Population structure; Salmonid fish; ectoparasite; gene flow; isolation by distance; networks