title: Reproductive efficiency and shade avoidance plasticity under simulated competition.
abstract: Plant strategy and life-history theories make different predictions about reproductive efficiency under competition. While strategy theory suggests under intense competition iteroparous perennial plants delay reproduction and semelparous annuals reproduce quickly, life-history theory predicts both annual and perennial plants increase resource allocation to reproduction under intense competition. We tested (1) how simulated competition influences reproductive efficiency and competitive ability (CA) of different plant life histories and growth forms; (2) whether life history or growth form is associated with CA; (3) whether shade avoidance plasticity is connected to reproductive efficiency under simulated competition. We examined plastic responses of 11 herbaceous species representing different life histories and growth forms to simulated competition (spectral shade). We found that both annual and perennial plants invested more to reproduction under simulated competition in accordance with life-history theory predictions. There was no significant difference between competitive abilities of different life histories, but across growth forms, erect species expressed greater CA (in terms of leaf number) than other growth forms. We also found that shade avoidance plasticity can increase the reproductive efficiency by capitalizing on the early life resource acquisition and conversion of these resources into reproduction. Therefore, we suggest that a reassessment of the interpretation of shade avoidance plasticity is necessary by revealing its role in reproduction, not only in competition of plants.
authors.affiliation: Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences UNSW Australia Sydney New South Wales 2052 Australia.
authors.forename: Fatih
authors.identifier: 0000-0002-4723-3640
authors.initials: F
authors.lastname: Fazlioglu
authors.affiliation: Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences UNSW Australia Sydney New South Wales 2052 Australia.
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Namazi
authors.affiliation: Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences UNSW Australia Sydney New South Wales 2052 Australia.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Bonser
keywords: Phenotypic plasticity; plant reproduction; shade avoidance; simulated competition