Population differentiation and phenotypic plasticity of wild and agrestal populations of the annual Anoda cristata (Malvaceae) growing in two contrasting habitats

Anoda cristata is a widely distributed annual weed in Mexico, which grows a s agrestal or naturally in disturbed and undisturbed vegetation, respective ly. Plants of this species are tolerated in orchards and corn-bean fields b y Mexican ethnic groups of Central Mexico. Leaves of the plants are used as a food source, and occasionally seeds are sown in orchards. Because Mexica ns have used Anoda cristata for a long time, it is possible that ecological and morphological characteristics of managed populations differ from those of wild populations. In this study, we analyzed phenotypic responses of tw o populations of A. cristata (wild and agrestal) growing in two habitats (f orest and cultivated field) comparing survivorship, and life history traits . Natural progenies from wild and agrestal populations of A. cristata were transplanted into a cultivated field and in the understory of a pine forest in a reciprocal transplant experiment. Results showed that the habitat of transplant and the origin of populations had significant effect on all plan t characters measured (growth, phenology, and biomass allocation), but the habitat x origin interaction was non-significant. In general, plants from t he agrestal population grew faster, reproduced earlier, and allocated more biomass to reproduction, than plants from the wild population. Similarly, s ignificant effects of habitat and origin on plant survivorship were detecte d, but the origin of populations explained the largest proportion of varian ce in plant survival. Most traits were phenotypically plastic but there wer e no differences in the magnitude or direction of the response between popu lations. In contrast both populations showed differentiation for most chara cter mean values. Population differentiation is possibly the result of gene tic differences driven by processes other than incipient domestication.