Summary• Although a major expectation of coevolutionary theory between plants and herbivores is the occurrence of reciprocal local adaptation, this has remained almost untested. Thus, we evaluated the presence and variation in the patterns of reciprocal local adaptation between an herbivorous insect and its host plant.• Two four-by-four cross-infestation experiments were performed under similar abiotic conditions. The first one was done under laboratory conditions to estimate herbivore individual performance while the second one was performed in a common garden to simultaneously estimate herbivore population growth rate as well as seed production and plant defenses (resistance and tolerance to herbivory).• The patterns of population differentiation for the herbivore and the plant were not independent of each other, showing all the possible outcomes from locally adapted to maladapted populations. These results indicate differences in the magnitude of local adaptation. While an association between resistance and herbivore performance was observed, there was no clear pattern between tolerance and herbivore local adaptation.• Our results demonstrated the occurrence of reciprocal local adaptation following the pattern expected by theory: when the herbivores or the plants were adapted, the other species was non-adapted or even maladapted.

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.

The cactus moth, Cactoblastis cactorum mainly distributed throughout central and northeastern Argentina was intentionally introduced in the Caribbean region in 1957 as a biological control agent of cacti species of the genus Opuntia. This moth invaded during the last 20–30 years the North American continent, threatening the major center of biodiversity of native Opuntia species. Although human induced and natural dispersal have been invocated to explain its expansion in the non-native distribution range, there is still no evidence to support natural dispersal. In particular, hurricanes are one of the major environmental factors affecting species dispersal in the region. In this study we used mitochondrial DNA to examine whether the spatial distribution of haplotype variation of C. cactorum is at least partially explained by hurricane trajectories within the Caribbean region. DNA sequences for the mitochondrial gene cytochrome oxidase I were obtained for a sample of 110 individuals from the Antillean islands. This information was combined with existing sequences in the GenBank for the same gene for the Caribbean and Florida (N = 132 sequences). Genetic diversity descriptors, a haplotypic network, a spatial analyses of molecular variance and a landscape genetic analysis of migration conditioned by hurricane tracks were conducted to test our hypothesis. Our results revealed a significant spatial grouping of haplotypes consistent with the more frequent hurricane trajectories in the Caribbean region. Significant isolation by distance conditioned by hurricane tracks was detected. Populations of Florida were genetically closer to those of Cuba than to the rest of the population sampled. Within the region, Cuba appears as a reservoir of genetic diversity increasing the risk of invasion to Mexico and the US. Despite commercial transportation of Opuntia promoted dispersal to Florida, our results support the hypothesis that natural disturbances such as hurricanes played a role dispersing this invasive insect. Future conservation programs of North American Opuntia species requires taking into account hurricane mediated dispersal events and permanent whole regional monitoring and international control policies to prevent future range expansions of C. cactorum.Fil: Andraca Gómez, Guadalupe. Universidad Nacional Autónoma de México; MéxicoFil: Ordano, Mariano Andrés. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Boege, Karina. Universidad Nacional Autónoma de México; MéxicoFil: Domínguez, César A.. Universidad Nacional Autónoma de México; MéxicoFil: Piñero, Daniel. Universidad Nacional Autónoma de México; MéxicoFil: Pérez Ishiwara, Rubén. Universidad Nacional Autónoma de México; MéxicoFil: Pérez Camacho, Jacqueline. Ministerio de Ciencia, Tecnología y Medio Ambiente. Instituto de Ecología y Sistemática; CubaFil: Cañizares, Maikel. Ministerio de Ciencia, Tecnología y Medio Ambiente. Instituto de Ecología y Sistemática; CubaFil: Fornoni, Juan. Universidad Nacional Autó...