CHALCOFF Vanina Ruth
congresos y reuniones científicas
Increasing pollination erosion towards an environmentally-determined distribution boundary in a South-Andean Proteaceae
CHALCOFF VANINA RUTH; EZCURRA CECILIA; AIZEN MARCELO ADRIÁN
San Carlos de Bariloche
Congreso; VI Southern Connection Congress; 2010
Variation in pollinator guild composition over the distribution of the geographic range of a plant species can generate a geographically structured mosaic of evolution, so that the degree of overlap with effective pollinators will generate evolutionary hot-spots or cold-spots. The objective of this study was to asses if the geographical distribution of plants can not only be imposed by environmental-driven limits, but also by the effect of reproductive collapse mediated by the absence of effective pollinators. Embothrium coccineum is a red flowered species from southern South America with a generalist pollination system. Whereas the western limit of its longitudinal distribution is physically determined by the Pacific Ocean, the eastern range appears environmentally limited by the arid Patagonian steppe. We determined its most effective pollinator and we evaluated the effect of environment and pollinator in its reproductive success. Despite being a generalist species, E. coccineum has one hummingbird species (Sephanoides sephaniodes) as its most efficient pollinator, and its reproductive success depends on its visitation frequency and the pollen deposited on stigmas, rather than on precipitation. Contrary to the sites where the most efficient pollinator is present (hot-spots), in populations where the pollinator is rare or absent (cold-spots) we recorded a reproductive collapse. These results strengthen the importance of pollinators as biotic controls of plant distributions.