Pollinators and herbivores interactively shape selection on strawberry
defence and attraction
Abstract
Plant-herbivore-pollinator interactions are of ecological relevance for
most angiosperms. However little is known on how plants evolve in
response – and in particular how these tripartite interactions
influence phenotypic selection on traits that link pollination and
herbivory. We here conducted a common garden experiment with woodland
strawberry (Fragaria vesca L.) to quantify pollinator- and
herbivore-mediated selection on nine traits related to plant defence and
attraction. Our results showed that pollinators imposed stronger
selection than herbivores on both direct and indirect (i.e.,
tritrophic-related) defence traits – whereas conflicting selection was
imposed on inflorescence density. However, in all cases, selection
imposed by one agent was context-dependant on the other, suggesting that
dynamic patterns of selection are likely a prevalent feature of these
interactions. Our findings highlight the significance of
plant-herbivore-pollinator interactions as potential drivers of
evolutionary change, and reveal that pollinators may play a generally
underappreciated role as selective agents on plant defence.