title: Daphnia parasite dynamics across multiple Caullerya epidemics indicate selection against common parasite genotypes.
abstract: Studies of parasite population dynamics in natural systems are crucial for our understanding of host-parasite coevolutionary processes. Some field studies have reported that host genotype frequencies in natural populations change over time according to parasite-driven negative frequency-dependent selection. However, the temporal patterns of parasite genotypes have rarely been investigated. Moreover, parasite-driven negative frequency-dependent selection is contingent on the existence of genetic specificity between hosts and parasites. In the present study, the population dynamics and host-genotype specificity of the ichthyosporean Caullerya mesnili, a common endoparasite of Daphnia water fleas, were analysed based on the observed sequence variation in the first internal transcribed spacer (ITS1) of the ribosomal DNA. The Daphnia population of lake Greifensee (Switzerland) was sampled and subjected to parasite screening and host genotyping during C. mesnili epidemics of four consecutive years. The ITS1 of wild-caught C. mesnili-infected Daphnia was sequenced using the 454 pyrosequencing platform. The relative frequencies of C. mesnili ITS1 sequences differed significantly among years: the most abundant C. mesnili ITS1 sequence decreased and rare sequences increased over the course of the study, a pattern consistent with negative frequency-dependent selection. However, only a weak signal of host-genotype specificity between C. mesnili and Daphnia genotypes was detected. Use of cutting edge genomic techniques will allow further investigation of the underlying micro-evolutionary relationships within the Daphnia-C. mesnili system.
authors.affiliation: Department of Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, D-12587 Berlin, Germany; Berlin Centre for Genomics in Biodiversity Research (BeGenDiv), Königin-Luise-Straße 6-8, D-14195 Berlin, Germany; Department of Biology II, Ludwig Maximilians University, Großhaderner Straße 2, D-82512 Planegg-Martinsried, Germany. Electronic address: gonzalez@igb-berlin.de.
authors.forename: Enrique
authors.initials: E
authors.lastname: González-Tortuero
authors.affiliation: Department of Biology II, Ludwig Maximilians University, Großhaderner Straße 2, D-82512 Planegg-Martinsried, Germany.
authors.forename: Jakub
authors.initials: J
authors.lastname: Rusek
authors.affiliation: Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Überlandstrasse 133, CH-8600 Dübendorf, Switzerland; Institute of Integrative Biology, ETH Zurich, Universitätstrasse 16, CH-8092 Zurich, Switzerland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Turko
authors.affiliation: Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, CZ-12844 Prague, Czech Republic.
authors.forename: Adam
authors.initials: A
authors.lastname: Petrusek
authors.affiliation: Department of Biology II, Ludwig Maximilians University, Großhaderner Straße 2, D-82512 Planegg-Martinsried, Germany.
authors.forename: Inbar
authors.initials: I
authors.lastname: Maayan
authors.affiliation: Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, CZ-12844 Prague, Czech Republic; Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.
authors.forename: Lubomír
authors.initials: L
authors.lastname: Piálek
authors.affiliation: Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Überlandstrasse 133, CH-8600 Dübendorf, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Tellenbach
authors.affiliation: Department of Biology II, Ludwig Maximilians University, Großhaderner Straße 2, D-82512 Planegg-Martinsried, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Gießler
authors.affiliation: Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Überlandstrasse 133, CH-8600 Dübendorf, Switzerland; Institute of Integrative Biology, ETH Zurich, Universitätstrasse 16, CH-8092 Zurich, Switzerland.
authors.forename: Piet
authors.initials: P
authors.lastname: Spaak
authors.affiliation: Department of Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, D-12587 Berlin, Germany; Department of Biology, Chemistry and Pharmacy, Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, D-14195 Berlin, Germany.
authors.forename: Justyna
authors.initials: J
authors.lastname: Wolinska
mesh_terms: D000818:Animals; D021903:DNA, Ribosomal Spacer; D003621:Daphnia / Q000235:genetics / Q000469:parasitology*; D005838:Genotype; D058507:Host Specificity; D006790:Host-Parasite Interactions / Q000235:genetics / Q000276:immunology; D050298:Mesomycetozoea / Q000235:genetics / Q000502:physiology*; D012641:Selection, Genetic; D013997:Time Factors
chemical_list: D021903:DNA, Ribosomal Spacer
keywords: Caullerya mesnili; Host-genotype specificity; Negative frequency-dependent selection; Parasite population dynamics