Pollinator-mediated gender conflicting selection on corolla tube length in a specialized hawkmoth-pollinated species in the Brazilian Cerrado.

VEIGA, P.; AMORIM, F.W.; BENITEZ-VIEYRA, S.

Campo Grande

Simposio; Ecology and Evolution of Plant Reproduction; 2017

Universidade Federal de Matto Grosso do Sul - European Society of Evolutionary Biology

Tocoyena formosa (Rubiaceae) is a hawkmoth-pollinated species widely distributed in the Brazilian Cerrado. This species presents a remarkable intrapopulational variation in corolla tube length throughout its distribution, that suggests that this trait may be subject to natural selection imposed by pollinators. However, seed consumption by pre-dispersal seed predators may also influence the outcome of pollinator-mediated selection via the female fitness. In this study, we manipulated the effect of mutualists and antagonists by performing exclusion experiments and used path analysis combined with structural equation modeling to examine the simultaneous effect of mutualists and antagonists to the selection on corolla tube length. We found pollinator-mediated selection via female fitness for longer corolla tubes. Selection imposed by pollinators remained strong even after accounting for the negative effect of antagonists. The nature of the pollination mechanism, in which pollen is dispersed in discrete clumps attached to the hawkmoth?s tongue, favors pollen flow from shorter to longer-tubed flowers. Thus, shorter-tubed flowers act mainly as pollen donors being favored through the male component of fitness. Therefore, the net effect of pollinator-mediated selection on corolla tube length depends on the direction and magnitude of the selective pressure acting simultaneously through both female and male components of fitness.