Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907.
Proc Natl Acad Sci U S A. 2023 Nov 28;120(48):e2306723120. doi: 10.1073/pnas.2306723120. Epub 2023 Nov 13.
Anthropogenic climate change has significantly altered the flowering times (i.e., phenology) of plants worldwide, affecting their reproduction, survival, and interactions. Recent studies utilizing herbarium specimens have uncovered significant intra- and inter-specific variation in flowering phenology and its response to changes in climate but have mostly been limited to animal-pollinated species. Thus, despite their economic and ecological importance, variation in phenological responses to climate remain largely unexplored among and within wind-pollinated dioecious species and across their sexes. Using both herbarium specimens and volunteer observations of cottonwood () species, we examined how phenological sensitivity to climate varies across species, their ranges, sexes, and phenophases. The timing of flowering varied significantly across and within species, as did their sensitivity to spring temperature. In particular, male flowering generally happened earlier in the season and was more sensitive to warming than female flowering. Further, the onset of flowering was more sensitive to changes in temperature than leaf out. Increased temporal gaps between male and female flowering time and between the first open flower date and leaf out date were predicted for the future under two climate change scenarios. These shifts will impact the efficacy of sexual reproduction and gene flow among species. Our study demonstrates significant inter- and intra-specific variation in phenology and its responses to environmental cues, across species' ranges, phenophases, and sex, in wind-pollinated species. These variations need to be considered to predict accurately the effects of climate change and assess their ecological and evolutionary consequences.
人为气候变化显著改变了全球植物的开花时间（即物候），影响了它们的繁殖、生存和相互作用。最近利用植物标本馆标本的研究揭示了开花物候及其对气候变化响应的显著种内和种间变异，但主要局限于动物授粉物种。因此，尽管它们具有经济和生态重要性，但风媒雌雄异株物种及其性别之间以及跨性别对气候的物候响应的变异在很大程度上仍未得到探索。本研究使用植物标本馆标本和志愿者对棉白杨（）物种的观测，研究了物候对气候的敏感性如何在物种、它们的分布范围、性别和物候阶段之间变化。开花时间在物种间和种内差异显著，对春季温度的敏感性也不同。特别是，雄性花通常在季节早期开放，对变暖比雌性花更敏感。此外，开花的开始比叶子的展开对温度变化更敏感。在两种气候变化情景下，未来雄性和雌性开花时间之间以及第一朵花开放日期和叶子展开日期之间的时间间隔预计会增加。这些变化将影响物种间有性繁殖和基因流动的效率。我们的研究表明，在风媒物种中，物候及其对环境线索的响应存在显著的种间和种内变异，跨越物种分布范围、物候阶段和性别。需要考虑这些变异，以准确预测气候变化的影响，并评估其生态和进化后果。
