Huang Xiaojuan, Chen Minyu, Wang Linlin, Yang Mingliu, Yang Nacai, Li Zhonghu, Duan Yuanwen
Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an 710069, China.
The Germplasm Bank of Wild Species, Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
Plants (Basel). 2022 May 31;11(11):1488. doi: 10.3390/plants11111488.
The transition from outcrossing to selfing is a common evolutionary trend in flowering plants, and floral traits change significantly with the evolution of selfing. Whether or not plant traits are subjected to selection remains an open question in species with mixed mating systems. We examined phenotypic selection in two populations of with different selfing rates. We found that the pollen-ovule ratio, seed size, plant height, spur length, and pollinator visitation rate in the population with the higher selfing rate were lower than those in the population with the lower selfing rate. Selfing provides reproductive assurance for populations when pollinator service is low, and the floral traits that are associated with selfing syndrome are evident in populations with a higher selfing rate but are subjected to weak selection in each of the two populations with different selfing rates. Directional selection for an early flowering time indicated that late blooming flowers could experience a risk of seed development in alpine environments, and for large plants, selection indicated that seed production could be limited by the available resources. The floral traits that are associated with pollinator attraction and specialization could be subjected to weak selection at the plant level as selfing evolves, and the selective pressures that are independent of pollinators might not change significantly; highlighting the selective biotic and abiotic pressures that shape the morphological traits of plant species and their independence from the mating system.
从异交向自交的转变是开花植物中常见的进化趋势，并且花部性状会随着自交的进化而发生显著变化。在具有混合交配系统的物种中，植物性状是否受到选择仍然是一个悬而未决的问题。我们研究了两个自交率不同的种群中的表型选择。我们发现，自交率较高的种群中的花粉 - 胚珠比、种子大小、株高、距长和传粉者访花率均低于自交率较低的种群。当传粉者服务水平较低时，自交为种群提供了繁殖保障，与自交综合征相关的花部性状在自交率较高的种群中很明显，但在两个自交率不同的种群中各自受到的选择都较弱。对早花时间的定向选择表明，在高山环境中，晚开花的花朵可能会面临种子发育的风险，而对于大型植株，选择表明种子产量可能受到可用资源的限制。随着自交的进化，与传粉者吸引和特化相关的花部性状在植物水平上可能受到较弱的选择，并且与传粉者无关的选择压力可能不会有显著变化；这突出了塑造植物物种形态性状的选择性生物和非生物压力以及它们与交配系统的独立性。
