BACKGROUND AND AIMS Sexual dimorphism for floral traits is common in dioecious plant species. Beyond its significance for understanding how selection acts on plant traits through male versus female reproductive function, sexual dimorphism has also been proposed as a possible risky characteristic for insect pollinated plants, as it could drive pollinators to forage mostly on male plants. However, even though most flowering plant species spread their flowering across several weeks or months, the temporal variation of floral phenotypes and sexual dimorphism are rarely investigated. METHODS We performed a survey of male and female plants from the dioecious generalist-pollinated Silenedioica (Caryophyllaceae) in a common garden experiment, over two consecutive flowering seasons. Flower number and floral size were measured each week, as well as pollen quantity and viability in male plants. KEY RESULTS Sexual dimorphism was found for all investigated floral traits, with males showing an overall higher investment in flower production and flower size. Males and females show a similar temporal decline in flower size. The temporal dynamics of daily flower number differed between sexes, with males showing a peak in the middle of their flowering season, whereas flower production by females was rather stable over time. At the scale of the experimental population, both individual and floral sex ratios appeared to vary across the flowering season. Moreover, because the onset of flowering varied among plants, the magnitude of sexual dimorphism in floral size also strongly fluctuated through time. CONCLUSIONS Capturing male / females differences with only one temporal measurement per population may not be informative. This opens stimulating questions about how pollinator behaviour and resulting pollination efficiency may vary across the flowering season.

中文翻译：

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雌雄异体物种中性二态性的时间动态


背景和目的花性状的两性二态性在雌雄异株的植物物种中很常见。除了对于理解选择如何通过雄性和雌性生殖功能对植物性状产生影响外，性二态性也被认为是昆虫授粉植物的一个可能的危险特征，因为它可能促使授粉媒介主要以雄性植物为食。然而，尽管大多数开花植物物种的开花期持续数周或数月，但花表型和性二态性的时间变化却很少被研究。方法我们在一个普通的花园实验中，对连续两个开花季节的雌雄异体、通才授粉的石竹科（石竹科）的雄性和雌性植物进行了调查。每周测量花数和花的大小，以及雄性植物的花粉数量和活力。主要结果 所有研究的花性状都发现了性别二态性，雄性在花卉产量和花朵大小方面表现出总体较高的投资。雄性和雌性在花大小方面表现出类似的时间下降。每日花朵数量的时间动态在性别之间有所不同，雄性在花季中期出现峰值，而雌性的花朵产量随着时间的推移相当稳定。在实验群体的规模上，个体和花朵的性别比例似乎在整个开花季节都有所不同。此外，由于植物之间开花的开始时间不同，花大小的两性异形程度也随着时间的推移而剧烈波动。结论 对于每个群体仅进行一次时间测量来捕捉男性/女性差异可能无法提供信息。 这就提出了一些令人兴奋的问题，即传粉媒介的行为和由此产生的授粉效率在整个开花季节可能会如何变化。