Repeated evolution of a reproductive polyphenism in plants is strongly associated with bilateral flower symmetry

第一作者：Simon Joly

第一单位：加拿大蒙特利尔植物园

通讯作者：Daniel J. Schoen

 Abstract 

非遗传多型性：Polyphenisms are a special type of phenotypic plasticity in which the products of development are not continuous but instead are separate and distinct phenotypes produced in the same genetic background.

闭花受精-概念：One of the most widespread polyphenisms in the flowering plants is cleistogamy, in which the same individual plant produces both open, cross-pollinated flowers as well as highly reduced and closed, self-pollinated (cleistogamous) flowers.

闭花受精-演化：Cleistogamy is not a rare evolutionary phenomenon. It has evolved independently at least 41 times. But what favors the evolution of cleistogamy is still largely unknown.

达尔文的假设-1：Darwin proposed a hypothesis that has never been properly tested. He observed that cleistogamy is more common in taxa with bilaterally symmetric (zygomorphic) flowers than in those with radially symmetric (actinomorphic) flowers.

达尔文的假设-2：Moreover, Darwin suggested that cleistogamous flowers help to ensure pollination, which he postulated is less certain in zygomorphic taxa that rely on more specialized groups of pollinators.

结果-1：Here, we combined the largest datasets on floral symmetry and cleistogamy and used phylogenetic approaches to show that cleistogamy is indeed disproportionately associated with zygomorphic flowers and that zygomorphic species are more likely to evolve cleistogamy than actinomorphic species.

结果-2：We also show that zygomorphic species are less capable of autonomous open-flower self-pollination (lower autofertility), suggesting that selection of cleistogamy via reproductive assurance in zygomorphic taxa could help account for Darwin’s observation.

结论：Our results provide support for the hypothesis that polyphenisms are favored when organisms encounter contrasting environments.

doi: https://doi.org/10.1016/j.cub.2021.01.009

Journal: Current Biology

Published date: Feb 03, 2021