The additive effects of pollinators and herbivores on the vine Bomarea salsilla (Alstroemeriaceae), remain spatially consistent in a fragmented forest

Abstract

Modifications in plant-mutualistic and plant-antagonistic interactions driven by habitat fragmentation may have far reaching consequences by affecting plant reproductive success and their microevolutionary dynamics. Mutualists (e.g., pollinators) and antagonists (e.g., herbivores) can exert non-additive effects on plant fitness, which is interpreted as evidence of a pathway for correlated evolution on mutualist- and antagonist-linked traits, respectively. We suggest that a decrease in pollination and herbivory due to habitat fragmentation and proximity to edges may lead plants to face non-correlated fitness effects (i.e., additivity) exerted by pollinators and herbivores. We assessed the effects of pollinators and herbivores on Bomarea salsilla seed set by separately and simultaneously excluding pollinators and herbivores in a fully factorial design. The exclusions were performed in the core and edge of a continuous forest, and in the core and edge of forest fragments. At all sites studied, pollinators, but not herbivores, affected plant fitness, exerting non-correlated fitness effects. Consequently, forest fragmentation and the creation of edge habitats seemed not to affect the pollinator- and herbivore-mediated selection pressures on B. salsilla .