背景:授粉媒介对花性状施加强烈的选择。的确,传粉者综合征是这些强大的选择力量的结果,但是其他非生物和生物因子也驱动花卉性状的进化并影响植物的繁殖。预计全球变化将对生物和非生物系统产生广泛影响,从而在未来条件下对花卉性状进行新的选择。
方法:全球变化降低了传粉媒介的丰度,改变了非生物条件,从而使开花植物物种暴露于新颖的选择压力套件。在这里,我们考虑生物和非生物因素如何相互作用以塑造各种花卉特征(选择目标)的表达和进化,包括花卉大小,颜色,生理学,奖励数量和质量,和长寿以及其他特征。我们研究了由气候因素施加的选择与传粉者介导的选择相冲突的情况。此外,我们探索花卉性状如何通过表型可塑性对环境变化做出反应,以及如何改变植物的繁殖力。在这次审查中,我们评估了全球变化如何改变花卉表型的表达和进化。
结论:花卉性状在多种相互作用的选择作用下进化。不同的代理人有时会产生相互冲突的选择。例如,传粉者通常喜欢大花,但是干旱胁迫有利于小花的进化,花器官的大小可以在这些对立的参与者介导的选择之间进行权衡。然而,很少有研究对选择的非生物和生物因子进行因素操纵,以解开它们的相对优势和选择方向。与考虑非生物因素如何改变这些性状的选择相比,文献更经常评估花性状对应激源的可塑性反应。此外,全球变化可能会通过改变互惠主义者和拮抗剂的丰度和社区组成以及新的非生物条件来改变选择性景观。我们鼓励未来的工作考虑一个更全面的花卉进化模型,随着全球变化的进展,这将对花卉进化和植物繁殖进行更有力的预测。
BACKGROUND: Pollinators impose strong selection on floral traits. Indeed, pollinator syndromes are the result of these strong selective forces, 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 under future conditions.
METHODS: Global 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 various floral characteristics (the targets of selection), including floral size, color, 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. In this review, we evaluate how global change may shift the expression and evolution of floral phenotypes.
CONCLUSIONS: Floral 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 favor 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 factorially manipulated abiotic and biotic agents of selection 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. Furthermore, global change will likely alter the selective landscape through changes in the abundance and community compositions of mutualists and antagonists and novel abiotic conditions. We encourage future work to consider a more holistic model of floral evolution, which will enable more robust predictions about floral evolution and plant reproduction as global change progresses.