title: Selection mosaic exerted by specialist and generalist herbivores on chemical and physical defense of Datura stramonium.
abstract: Selection exerted by herbivores is a major force driving the evolution of plant defensive characters such as leaf trichomes or secondary metabolites. However, plant defense expression is highly variable among populations and identifying the sources of this variation remains a major challenge. Plant populations are often distributed across broad geographic ranges and are exposed to different herbivore communities, ranging from generalists (that feed on diverse plant species) to specialists (that feed on a restricted group of plants). We studied eight populations of the plant Datura stramonium usually eaten by specialist or generalist herbivores, in order to examine whether the pattern of phenotypic selection on secondary compounds (atropine and scopolamine) and a physical defense (trichome density) can explain geographic variation in these traits. Following co-evolutionary theory, we evaluated whether a more derived alkaloid (scopolamine) confers higher fitness benefits than its precursor (atropine), and whether this effect differs between specialist and generalist herbivores. Our results showed consistent directional selection in almost all populations and herbivores to reduce the concentration of atropine. The most derived alkaloid (scopolamine) was favored in only one of the populations, which is dominated by a generalist herbivore. In general, the patterns of selection support the existence of a selection mosaic and accounts for the positive correlation observed between atropine concentration and plant damage by herbivores recorded in previous studies.
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Guillermo
authors: G
authors: Castillo
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Laura L
authors: LL
authors: Cruz
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Rosalinda
authors: R
authors: Tapia-López
authors: Erika
authors: E
authors: Olmedo-Vicente
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Eika
authors: E
authors: Olmedo-Vicente
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Diego
authors: D
authors: Carmona
authors: Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Ana Luisa
authors: AL
authors: Anaya-Lang
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Juan
authors: J
authors: Fornoni
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Guadalupe
authors: G
authors: Andraca-Gómez
authors: Departamento de Biología, Universidad Autónoma Metropolitana Iztapalapa, México City, Distrito Federal, México.
authors: Pedro L
authors: PL
authors: Valverde
authors: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Distrito Federal, México.
authors: Juan
authors: J
authors: Núñez-Farfán
mesh_terms: D000818:Animals; D001285:Atropine / Q000378:metabolism; D013286:Datura stramonium / Q000033:anatomy & histology / Q000502:physiology*; D060434:Herbivory; D008800:Mexico; D010641:Phenotype; D063148:Plant Dispersal; D012641:Selection, Genetic; D064201:Trichomes / Q000033:anatomy & histology / Q000502:physiology
chemical_list: D001285:Atropine