Experimental reduction in interaction intensity strongly affects biotic selection. Issue 11 (November 2016)

• Record Type: Journal Article
• Authors: Sletvold, Nina; Ågren, Jon
• Is Part Of: Ecology. Volume 97:Issue 11(2016)
• Page Start: 3091
• Page End: 3098
• Publication Date: 2016-11
• Subjects: floral evolution -- Gymnadenia conopsea -- natural selection -- opportunity for selection -- plant–animal interactions -- pollen limitation -- pollinator‐mediated selection -- selection intensity -- trait–fitness covariance; Ecology -- Periodicals; Ecology -- Periodicals; Écologie -- Périodiques; Ecologie; Écologie; Écologie animale; Écologie végétale; Ecology; Periodicals; 577.05
• DOI: 10.1002/ecy.1554
• Languages: English
• ISSNs: 0012-9658

Abstract

Abstract: The link between biotic interaction intensity and strength of selection is of fundamental interest for understanding biotically driven diversification and predicting the consequences of environmental change. The strength of selection resulting from biotic interactions is determined by the strength of the interaction and by the covariance between fitness and the trait under selection. When the relationship between trait and absolute fitness is constant, selection strength should be a direct function of mean population interaction intensity. To test this prediction, we excluded pollinators for intervals of different length to induce five levels of pollination intensity within a single plant population. Pollen limitation (PL) increased from 0 to 0.77 across treatments, accompanied by a fivefold increase in the opportunity for selection. Trait–fitness covariance declined with PL for number of flowers, but varied little for other traits. Pollinator‐mediated selection on plant height, corolla size, and spur length increased by 91%, 34%, and 330%, respectively, in the most severely pollen‐limited treatment compared to open‐pollinated plants. The results indicate that realized biotic selection can be predicted from mean population interaction intensity when variation in trait–fitness covariance is limited, and that declines in pollination intensity will strongly increase selection on traits involved in the interaction.