title: Local adaptation drives thermal tolerance among parasite populations: a common garden experiment.
abstract: Understanding the evolutionary responses of organisms to thermal regimes is of prime importance to better predict their ability to cope with ongoing climate change. Although this question has attracted interest in free-living organisms, whether or not infectious diseases have evolved heterogeneous responses to climate is still an open question. Here, we ran a common garden experiment using the fish ectoparasite Tracheliastes polycolpus, (i) to test whether parasites living in thermally heterogeneous rivers respond differently to an experimental thermal gradient and (ii) to determine the evolutionary processes (natural selection or genetic drift) underlying these responses. We demonstrated that the reaction norms involving the survival rate of the parasite larvae (i.e. the infective stage) across a temperature gradient significantly varied among six parasite populations. Using a Qst/Fst approach and phenotype-environment associations, we further showed that the evolution of survival rate partly depended upon temperature regimes experienced in situ, and was mostly underlined by diversifying selection, but also-to some extent-by stabilizing selection and genetic drift. This evolutionary response led to population divergences in thermal tolerance across the landscape, which has implications for predicting the effects of future climate change.
authors.affiliation: Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France nelize35@gmail.com.
authors.forename: Elise
authors.initials: E
authors.lastname: Mazé-Guilmo
authors.affiliation: Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France CNRS, UPS, École Nationale de Formation Agronomique (ENFA); UMR5174 EDB (Laboratoire Évolution and Diversité Biologique), 118 route de Narbonne, Toulouse cedex 4 31062, France.
authors.forename: Simon
authors.identifier: 0000-0002-3843-589X
authors.initials: S
authors.lastname: Blanchet
authors.affiliation: Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France Department of Biosciences, College of Science, University of Swansea, Swansea SA2 8PP, UK.
authors.forename: Olivier
authors.initials: O
authors.lastname: Rey
authors.affiliation: Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Canto
authors.affiliation: CNRS, UPS, École Nationale de Formation Agronomique (ENFA); UMR5174 EDB (Laboratoire Évolution and Diversité Biologique), 118 route de Narbonne, Toulouse cedex 4 31062, France Université de Toulouse, UPS, UMR 5174 (EDB), 118 route de Narbonne, Toulouse cedex 4 31062, France geraldine.loot@univ-tlse3.fr.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Loot
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000818:Animals; D033342:Copepoda / Q000235:genetics / Q000502:physiology*; D003530:Cyprinidae / Q000469:parasitology*; D005260:Female; D005602:France; D006790:Host-Parasite Interactions; D007814:Larva; D019655:Quantitative Trait, Heritable; D015996:Survival Rate; D013696:Temperature
keywords: Qst/Fst; common garden experiment; ectoparasites; generalism; pre-adaptation; thermal reaction norms