Reproductive isolation is mediated by pollen incompatibility in sympatric populations of two Arnebia species

Ecology and Evolution

Lin-Lin Wang²  Chan Zhang³  Bin Tian²  Xu-Dong Sun²  Wen Guo²  Ting-Feng Zhang¹  Yong-Ping Yang² 

[1] College of Agriculture and Biotechnology, Hexi University, Zhangye, Gansu, China;Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China;College of Life Sciences, Henan Normal University, Xinxiang, Henan, China

关键词: Floral traits;    natural selection;    pollen export;    pollinator preference;    seed set;   

DOI  :  10.1002/ece3.1849

来源: Wiley

【 摘 要 】

Abstract

To explore uncertain aspects of the processes that maintain species boundaries, we evaluated contributions of pre- and postpollination reproductive isolation mechanisms in sympatric populations of Arnebia guttata and A. szechenyi. For this, we investigated their phylogenetic relationships, traits, microenvironments, pollinator visits, action of natural selection on floral traits, and the outcome of hand pollination between the two species. Phylogenetic analysis indicates that A. szechenyi is a derived species that could be closely related to A. guttata, and both could be diploid species. Arnebia guttata flowers have larger parts than A. szechenyi flowers, but smaller nectar guides. Soil supporting A. szechenyi had higher water contents than soil supporting neighboring populations of A. guttata (in accordance with their geographical distributions). The pollinators shared by the two species preferred A. szechenyi flowers, but interspecific visitations were frequent. We found evidence of conflicting selection pressures on floral tube length, flower diameter and nectar guide size mediated via male fitness, and on flower diameter and floral tube diameter via female fitness. Hand-pollination experiments indicate complete pollen incompatibility between the two species. Our results suggest that postpollination prezygotic mechanisms are largely responsible for reproductive isolation of sympatric populations of the two Arnebia species.

【 授权许可】

CC BY   
© 2015 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.