title: Different rates of defense evolution and niche preferences in clonal and nonclonal milkweeds (Asclepias spp.).
abstract: Given the dual role of many plant traits to tolerate both herbivore attack and abiotic stress, the climatic niche of a species should be integrated into the study of plant defense strategies. Here we investigate the impact of plant reproductive strategy and components of species' climatic niche on the rate of chemical defense evolution in the milkweeds using a common garden experiment of 49 species. We found that across Asclepias species, clonal reproduction repeatedly evolved in lower temperature conditions, in species generally producing low concentrations of a toxic defense (cardenolides). Additionally, we found that rates of cardenolide evolution were lower for clonal than for nonclonal species. We thus conclude that because the clonal strategy is based on survival, long generation times, and is associated with tolerance of herbivory, it may be an alternative to toxicity in colder ecosystems. Taken together, these results indicate that the rate of chemical defense evolution is influenced by the intersection of life-history strategy and climatic niches into which plants radiate.
authors.affiliation: Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland.|Landscape Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland.
authors.forename: Loïc
authors.initials: L
authors.lastname: Pellissier
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.|Swiss Institute of Bioinformatics, Génopode Building, 1015, Lausanne, Switzerland.
authors.forename: Glenn
authors.initials: G
authors.lastname: Litsios
authors.affiliation: Department of Botany, Oklahoma State University, Stillwater, OK, 74078-3013, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Fishbein
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.|Swiss Institute of Bioinformatics, Génopode Building, 1015, Lausanne, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Salamin
authors.affiliation: Department of Ecology and Evolutionary Biology, and Department of Entomology, Cornell University, 215 Tower Road, Ithaca, NY, 14853, USA.
authors.forename: Anurag A
authors.initials: AA
authors.lastname: Agrawal
authors.affiliation: Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
authors.forename: Sergio
authors.initials: S
authors.lastname: Rasmann
mesh_terms: D031108:Asclepias / Q000502:physiology*; D005075:Biological Evolution; D018533:Biomass; D017753:Ecosystem; D010802:Phylogeny; D018517:Plant Roots / Q000502:physiology; D025341:Principal Component Analysis; D019655:Quantitative Trait, Heritable; D013045:Species Specificity
keywords: cardenolides; climatic niche; clonality; resistance; tolerance; trait evolution