Natural selection on floral traits of Lobelia siphilitica by pollinators and a specialist pre-dispersal seed predator.

摘要

Pre-dispersal seed predators which oviposit within buds or flowers of outcrossing, animal-pollinated plants depend on pollinators for seed production. Therefore seed predators are expected to choose flowers that are attractive to pollinators, providing a mechanism by which seed predators could impose selection on floral traits. However to date, few studies have measured the agents of selection. Survey data of pre-dispersal seed predation of Lobelia siphilitica by its specialist seed predator Cleopmiarus hispidulus suggests floral phenology as a target of selection. I manipulated pollination and phenology in a field experiment and measured natural selection on floral traits of L. siphilitica to determine the relative strength of selection by both pollinators and seed predators and whether phenology was a target of selection. I found pre-dispersal seed predators, not pollinators, were selecting floral traits. However, selection on some traits could not be attributed to either organism, suggesting the importance of other ecological factors.