Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, SE-106 91, Sweden.
Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden.
Am J Bot. 2024 Oct;111(10):e16405. doi: 10.1002/ajb2.16405. Epub 2024 Sep 15.
In plants, within-individual trait variation might result from mechanisms related to ontogenetic contingency, i.e., to the position of a particular structure within the plant, previous developmental events, and/or the developmental environment. Flower position within inflorescences as well as inflorescence position within plants can influence resource provisioning, phenology, biotic interactions, and reproductive success. Despite the potential implications of within-individual variation in plant reproductive phenotypes, its causes and effects on reproductive success are still little explored.
We assessed how reproductive success, in terms of fruit and seed set, and seed predation of 5883 flowers in Lathyrus vernus were influenced by their position within and among racemes, to what extent relationships between flower position and reproductive success and seed predation were mediated by phenology, and if positional effects on reproductive success depended on the external environment.
In three years, basal flowers and racemes opened earlier and had higher fruit set than distal. Basal flowers also experienced higher seed predation. Differences among racemes in fruit and seed set were largely related to phenology, while differences in fruit set, seed set, and seed predation within racemes were not. In one year, differences in fruit set among flowers at different positions depended on flowering duration.
Our results highlight the important role of ontogenetic contingency for within-individual variation in phenology and reproductive success. As the spatial distribution of reproductive structures affects both within-plant trait distributions and fitness, it is a likely target for natural selection.
在植物中，个体内的性状变异可能是由与个体发育偶然性相关的机制引起的，即与特定结构在植物中的位置、先前的发育事件和/或发育环境有关。花序内花朵的位置以及植物内花序的位置可以影响资源供应、物候、生物相互作用和生殖成功。尽管植物生殖表型的个体内变异具有潜在影响，但它对生殖成功的原因和影响仍知之甚少。
我们评估了 5883 朵毛茛花的生殖成功，即果实和种子的设置以及种子捕食，这些花的位置在总状花序内和之间，以及花的位置与生殖成功和种子捕食之间的关系在多大程度上受到物候的影响，以及位置对生殖成功的影响是否取决于外部环境。
在三年中，基部花朵和总状花序比远端花朵更早开放，果实设置更高。基部花朵也经历了更高的种子捕食。果实和种子设置的种间差异主要与物候有关，而总状花序内果实设置、种子设置和种子捕食的差异则不是。在一年中，不同位置花朵的果实设置差异取决于开花持续时间。
我们的结果强调了个体发育偶然性在物候和生殖成功个体内变异中的重要作用。由于生殖结构的空间分布影响植物内的性状分布和适应性，因此它可能成为自然选择的目标。
