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Abstract BackgroundPollinators impose strong selection on floral traits, but other abiotic and biotic agents also drive the evolution of floral traits and influence plant reproduction. Global change is expected to have widespread effects on biotic and abiotic systems, resulting in novel selection on floral traits in future conditions. ScopeGlobal change has depressed pollinator abundance and altered abiotic conditions, thereby exposing flowering plant species to novel suites of selective pressures. Here, we consider how biotic and abiotic factors interact to shape the expression and evolution of floral characteristics (the targets of selection), including floral size, colour, physiology, reward quantity and quality, and longevity, amongst other traits. We examine cases in which selection imposed by climatic factors conflicts with pollinator-mediated selection. Additionally, we explore how floral traits respond to environmental changes through phenotypic plasticity and how that can alter plant fecundity. Throughout this review, we evaluate how global change might shift the expression and evolution of floral phenotypes. ConclusionsFloral traits evolve in response to multiple interacting agents of selection. Different agents can sometimes exert conflicting selection. For example, pollinators often prefer large flowers, but drought stress can favour the evolution of smaller flowers, and the size of floral organs can evolve as a trade-off between selection mediated by these opposing actors. Nevertheless, few studies have manipulated abiotic and biotic agents of selection factorially to disentangle their relative strengths and directions of selection. The literature has more often evaluated plastic responses of floral traits to stressors than it has considered how abiotic factors alter selection on these traits. Global change will likely alter the selective landscape through changes in the abundance and community composition of mutualists and antagonists and novel abiotic conditions. We encourage future work to consider the effects of abiotic and biotic agents of selection on floral evolution, which will enable more robust predictions about floral evolution and plant reproduction as global change progresses.
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Does pollination interact with the abiotic environment to affect plant reproduction?
Abstract Background and AimsAbiotic and biotic components of the environment both limit plant reproduction, but how they interact with one another in combination is less understood. Understanding these interactions is especially relevant because abiotic and biotic environmental components respond differently to various drivers of global change. Here, we aim to understand whether the effects of pollination (biotic component) on plant reproduction depend on soil moisture (abiotic component), two factors known to affect plant reproduction and that are changing with global change. MethodsWe conducted pollen supplementation experiments for two plant species, Delphinium nuttallianum and Hydrophyllum fendleri, in subalpine meadows in the Western USA across 4 years that varied in soil moisture. In a separate 1-year field experiment, we crossed water addition with pollen supplementation factorially. We measured the proportion of fruit set, seeds per fruit and seeds per plant, in addition to stomatal conductance, to determine whether plant physiology responded to watering. Key ResultsIn the 4-year study, only H. fendleri reproduction was pollen limited, and this occurred independently of soil moisture. Experimental water addition significantly increased soil moisture and stomatal conductance for both species. The effect of pollen addition on reproduction depended on the watering treatment only for H. fendleri fruit production. Reproduction in D. nuttallianum was not significantly affected by pollen addition or water addition, but it did respond to interannual variation in soil moisture. ConclusionsAlthough we found some evidence for the effect of a biotic interaction depending on abiotic conditions, it was only for one aspect of reproduction in one species, and it was in an unexpected direction. Our work highlights interactions between the abiotic and biotic components of the environment as an area of further research for improving our understanding of how plant reproduction responds to global change.
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- Award ID(s):
- 1754518
- PAR ID:
- 10570908
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Annals of Botany
- Volume:
- 135
- Issue:
- 1-2
- ISSN:
- 0305-7364
- Format(s):
- Medium: X Size: p. 141-152
- Size(s):
- p. 141-152
- Sponsoring Org:
- National Science Foundation
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