title: The potential for arms race and Red Queen coevolution in a protist host-parasite system.
abstract: The dynamics and consequences of host-parasite coevolution depend on the nature of host genotype-by-parasite genotype interactions (G × G) for host and parasite fitness. G × G with crossing reaction norms can yield cyclic dynamics of allele frequencies ("Red Queen" dynamics) while G × G where the variance among host genotypes differs between parasite genotypes results in selective sweeps ("arms race" dynamics). Here, we investigate the relative potential for arms race and Red Queen coevolution in a protist host-parasite system, the dinoflagellate Alexandrium minutum and its parasite Parvilucifera sinerae. We challenged nine different clones of A. minutum with 10 clones of P. sinerae in a fully factorial design and measured infection success and host and parasite fitness. Each host genotype was successfully infected by four to ten of the parasite genotypes. There were strong G × Gs for infection success, as well as both host and parasite fitness. About three quarters of the G × G variance components for host and parasite fitness were due to crossing reaction norms. There were no general costs of resistance or infectivity. We conclude that there is high potential for Red Queen dynamics in this host-parasite system.
authors.affiliation: Department of Biology, Lund University Ecology Building, SE-22362, Lund, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Råberg
authors.affiliation: Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC Pg. Marítim de la Barceloneta, 37-49, E08003, Barcelona, Spain.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Alacid
authors.affiliation: Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC Pg. Marítim de la Barceloneta, 37-49, E08003, Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Garces
authors.affiliation: Department of Biology, Lund University Ecology Building, SE-22362, Lund, Sweden ; Centro Oceanográfico de Vigo, IEO (Instituto Español de Oceanografía) Subida a Radio Faro 50, 36390, Vigo, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Figueroa
keywords: Alexandrium minutum; Parvilucifera sinerae; dinoflagellate; fluctuating selection; frequency-dependent selection