J Plant Ecol ›› 2023, Vol. 16 ›› Issue (3): rtac109.DOI: 10.1093/jpe/rtac109

• Research Articles •    

The nonlinear change in pollinator assemblages and self-mating syndromes of Primula atrodentata along elevation gradients

Yin-Mei Ma, Yong-Peng Cha, Zhao-Li Tong, Jie Zhang, Qing-Jun Li*   

  1. Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China
  • Received:2022-05-07 Revised:2022-10-08 Accepted:2022-12-20 Online:2022-12-29 Published:2023-06-01
  • Contact: E-mail: qingjun.li@ynu.edu.cn


Abstract: The reproductive strategies of alpine plants are often altered by environmental changes caused by changes in the spatial distribution of the gradient. However, few studies have investigated whether reproductive patterns of the same species vary with elevation. Three natural populations of Primula atrodentata, which are distributed in the eastern Himalayas and have a long flowering period, were selected along the elevation gradients in Shergyla Mountain, Tibet, China. Morph ratio investigation, floral trait measurement, pollinator observation and manipulated pollination experiments were conducted to explore the changes in self-compatibility and floral traits associated with the selfing syndrome along elevation gradients. We found that the breeding system of the S-morph is facultative outcrossing, and that of the L-morph is obligatory outcrossing. We further found that with increasing elevation, the number of pollen and ovules, anther-stigma distance, and inbreeding depression index first increased and then decreased, whereas the seeds per fruit and seed-setting rate under hand self-pollination, pollen limitation and self-incompatibility index tended to decrease first, but then increased. In addition, pollinator diversity and visiting frequency were the highest at the middle elevation (4050 population), which can better explain the nonlinear change in self-fertility with elevation. Our findings provide insights into the evolutionary pattern of self-compatibility in alpine plants along elevational gradients.

Key words: breeding system, herkogamy, inbreeding depression, morph ratio, self-compatibility

高山植物的繁殖策略往往随分布海拔的增加逐渐向自交转变。然而,同一植物在不同种群的繁殖模式是否随海拔梯度的差异而发生变化,还未得到充分的研究。本研究以二型花柱植物白心球花报春(Primula atrodentata)为研究对象,通过对其在西藏自治区林芝市色季拉山广分布的低(3400 m)、中(4050 m)和高(4500 m) 3个自然居群进行表型比调查、花特征测量、传粉者观察和授粉操控实验,以探究自交亲和性和与自交综合征相关的花特征沿海拔梯度的变化。研究结果表明,白心球花报春长柱型植株繁育系统为专性异交,而短柱型植株繁育系统为兼性异交。随海拔的升高,短柱型自交的结籽数、百粒重、萌发率和自交不亲和指数具有先下降后升高趋势,而花粉数、胚珠数、雌雄异位程度和近交衰退指数具有先升高后下降的趋势。此外,在3个居群中,中间海拔居群的传粉昆虫种类丰富度、访花频率也最高,相应地其授粉限制程度低,这可以很好地解释白心球花报春自交随海拔的非线性变化。本研究为高山植物自交亲和性沿海拔梯度的进化模式提供了不同的见解。

关键词: 繁育系统, 雌雄异位, 近交衰退, 表型比, 自交亲和性