¿Las plantas exóticas leñosas dependen de los polinizadores para reproducirse? Un estudio de caso en las Sierras de la Ventana (Argentina)

Abstract

Most of the flowering plants depend on pollinators, in different degrees, for their reproduction. The degree of pollinator dependence is especially important in exotic plants because it could determine their colonization success in new locations. The objective of this study was to determine the degree of pollinator dependence in five exotic entomophilous plant species in a Pampean grassland located in Sierra de Ventana. It was determined if the differences in dependency are related to the geographic location and the phylogeny of plant species. The plants species were Spartium junceum, Genista monspessulana, Prunus mahaleb, Rosa rubiginosa and Rubus ulmifolius. Sampling was carried out in the Ernesto Tornquist Provincial Park and in surrounding areas (Buenos Aires Province). During the flowering peak of each species and in different sites, two treatments were undertaken in pre-bagged flowers: self-pollination and cross-pollination. Also, others pre-bagged flowers were left without pollination as control. Later, the probability of fruit develop and seed set under the two treatments and the control were assessed. Finally, the results of this study were compared with studies carried out in other regions (except for R. ulmifolius). The studied plant species showed a varied response to pollinator dependence, from very dependent species, such as S. junceum, G. monspessulana and P. mahaleb, to low dependent species such as R. rubiginosa y R. ulmifolius. Our results indicate that pollinator dependence can be variable in plants species that are colonizing non-native habitats. Furthermore, there are variations in the degree of pollinator dependency according to the geographical area, except for R. rubiginosa, showing that the geographical location can influence the dependence on pollinators for woody plants.