Seed production and autonomous self-pollination ability differ between the narrowly distributed Ipomoea rubriflora and its widespread congener I purpurea (Convolvulaceae).

ASTEGIANO J, GALETTO L, FUNES G & MUSICANTE M.

Morelia, México

Congreso; Annual Meeting of the Association for Tropical biology and Conservation; 2007

Association for Tropical Biology and Conservation

Features that determine the persistence and colonization ability of species may influence regional distribution patterns. Therefore, narrowly distributed plants may show less reproductive success than their widespread congeners, because of less pollinator visitation rates or less autonomous self-pollination ability. The objective of this study is to examine whether the individual reproductive success, levels of autonomous self-pollination, pollinator richness and visitation rates differ between the narrowly distributed annual vine Ipomoea rubriflora (Convolvulaceae) and its widespread congener I. purpurea. Data were obtained from two sites of Bosque Chaqueño Serrano, a subtropical dry forest from central Argentina. Sites were located at the distributional boundaries of both species where they grow sympatrically. We obtained three measures of individual reproductive success in five randomly marked individuals in each population: fruit set, seed set and total individual seed production. Pollinator richness and visitation rates were obtained from floral censuses. Autonomous self-pollination fruit and seed set were evaluated in five individuals from one population. We obtained a relative measure of autonomous self-pollination ability by comparing autonomous self-pollinated and natural levels of fruit and seed set. Natural individual fruit and seed set did not differ between species. However, total individual seed production was lower in I rubriflora. This species was pollinated by one species of hummingbird, whereas I. purpurea was pollinated by several Hymenoptera and Lepidoptera species. However, visitation rates did not differ between species. Relative autonomous self-pollination fruit set was lower in I. rubriflora, but seed set did not differ between species. The lower total individual seed production of the annual vine I. rubriflora may determine its lower current abundance at the populations studied and limit the colonization of new sites. Indeed, its lower autonomous self-pollination ability may determine more dependence on pollinators to produce seeds and therefore, less ability to buffer adverse years in pollinator service.