Zhang Hai-Ping, Tao Zhi-Bin, Trunschke Judith, Shrestha Mani, Scaccabarozzi Daniela, Wang Hong, Ren Zong-Xin
CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2022 Jun 22;13:908852. doi: 10.3389/fpls.2022.908852. eCollection 2022.
Comparison and quantification of multiple pre- and post-pollination barriers to interspecific hybridization are important to understand the factors promoting reproductive isolation. Such isolating factors have been studied recently in many flowering plant species which seek after the general roles and relative strengths of different pre- and post-pollination barriers. In this study, we quantified six isolating factors (ecogeographic isolation, phenological isolation, pollinator isolation, pollinia-pistil interactions, fruit production, and seed development) that could possibly be acting as reproductive barriers at different stages among three sympatric species (, , and ). These three species overlap geographically but occupy different microhabitats varying in soil water content. They were isolated through pollinator interactions both ethologically (pollinator preference) and mechanically (pollinia attachment site), but to a variable degree for different species pairs. Interspecific crosses between and result in high fruit set, and embryo development suggested weak post-pollination barriers, whereas bidirectional crosses of with either of the other two species fail to produce fruits. Our results revealed that pollinators were the most important isolating barrier including both ethological and mechanical mechanisms, to maintain the boundaries among these three sympatric species. Our study also highlights the importance of a combination of pre-and post-pollination barriers for species co-existence in Orchidaceae.
比较和量化种间杂交授粉前后的多种障碍对于理解促进生殖隔离的因素很重要。最近，在许多开花植物物种中对这类隔离因素进行了研究，这些研究旨在探寻不同授粉前后障碍的一般作用和相对强度。在本研究中，我们量化了六个可能在三个同域分布物种（、和）不同阶段充当生殖障碍的隔离因素（生态地理隔离、物候隔离、传粉者隔离、花粉块与雌蕊相互作用、果实形成和种子发育）。这三个物种在地理上有重叠，但占据不同的微生境，土壤含水量各不相同。它们通过传粉者相互作用在行为学上（传粉者偏好）和机械学上（花粉块附着部位）被隔离，但不同物种对的隔离程度有所不同。与之间的种间杂交产生了较高的坐果率，胚胎发育表明授粉后障碍较弱，而与其他两个物种中的任何一个进行的双向杂交均未产生果实。我们的结果表明，传粉者是包括行为学和机械学机制在内的维持这三个同域分布物种界限的最重要隔离障碍。我们的研究还强调了授粉前后障碍的组合对于兰科植物物种共存的重要性。
