title: Host specialist clownfishes are environmental niche generalists.
abstract: Why generalist and specialist species coexist in nature is a question that has interested evolutionary biologists for a long time. While the coexistence of specialists and generalists exploiting resources on a single ecological dimension has been theoretically and empirically explored, biological systems with multiple resource dimensions (e.g. trophic, ecological) are less well understood. Yet, such systems may provide an alternative to the classical theory of stable evolutionary coexistence of generalist and specialist species on a single resource dimension. We explore such systems and the potential trade-offs between different resource dimensions in clownfishes. All species of this iconic clade are obligate mutualists with sea anemones yet show interspecific variation in anemone host specificity. Moreover, clownfishes developed variable environmental specialization across their distribution. In this study, we test for the existence of a relationship between host-specificity (number of anemones associated with a clownfish species) and environmental-specificity (expressed as the size of the ecological niche breadth across climatic gradients). We find a negative correlation between host range and environmental specificities in temperature, salinity and pH, probably indicating a trade-off between both types of specialization forcing species to specialize only in a single direction. Trade-offs in a multi-dimensional resource space could be a novel way of explaining the coexistence of generalist and specialists.
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, Quartier Sorge, 1015 Lausanne, Switzerland.
authors.forename: Glenn
authors.initials: G
authors.lastname: Litsios
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, Quartier Sorge, 1015 Lausanne, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kostikova
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, Quartier Sorge, 1015 Lausanne, Switzerland nicolas.salamin@unil.ch.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Salamin
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017753:Ecosystem; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D012615:Sea Anemones / Q000502:physiology*; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D029941:Fish Proteins
keywords: anemone; anemonefish; intraspecific variation; mutualism; trade-off