Pre- and post- zygotic reproductive isolation between co- occurring Mussaenda pubescens var. alba and M. shikokiana ( Rubiaceae)
Pre- and post- zygotic reproductive isolation between co- occurring Mussaenda pubescens var. alba and M. shikokiana ( Rubiaceae)
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DOI：
10.1111/jipb.12140
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发表时间：
2014-04-01
影响因子：
11.4
通讯作者：
Zhang, Dianxiang
中科院分区：
文献类型：
--
作者：
Chen, Shi;Luo, Zhonglai;Zhang, Dianxiang
生殖隔离是物种形成的基本要求，包括几个连续的阶段。很少有研究已经确定的相对贡献的前和后合子生殖隔离在植物中，特别是在花的形式有明显分化的相关物种之间。探讨同域分布的玉叶金花生殖隔离的机制。对广西产的白花玉叶金花（Mussaenda alba）和四季玉叶金花（Mussaenda shikokiana）的开花物候、昆虫访花规律进行了观察，并进行了授粉试验和人工杂交。这两个物种有重叠的开花时间，并由重叠的传粉者授粉，但它们的相对重要性与M。pubescens是蜜蜂和M. shikokiana更常见于蝴蝶。使用营养和花的字符和基于核核糖体内部和外部转录间隔区的分子证据，我们检测到7个自然发生的杂交种之间的样本约125个人。杂种的特点是形态，最接近他们的母本的叶绿体证据的基础上。人工合成和自然杂交的研究表明，杂交种子发芽率很低，自然发生的杂交表现出花粉不育。合子后的生殖隔离机制在限制共生物种之间的基因交换和维持同域地区物种的完整性方面发挥着重要作用。
Reproductive isolation is a fundamental requirement for speciation and includes several sequential stages. Few studies have determined the relative contributions of pre- and post-zygotic reproductive isolation in plants, especially between relative species with clear differentiation in flower form. To investigate the mechanisms responsible for reproductive isolation in sympatric Mussaenda pubescens var. alba and Mussaenda shikokiana (Rubiaceae) in Guangxi Province, China, we made observations of flowering phenology, patterns of insect visitation, and conducted pollination experiments, including artificial hybridization. The two species had overlapping flowering times and were pollinated by overlapping pollinators; however, their relative importance differed significantly with M. pubescens visited more commonly by bees and M. shikokiana more frequently by butterflies. Using vegetative and floral characters and molecular evidence based on nuclear ribosomal internal and external transcribed spacer regions we detected seven naturally occurring hybrids among a sample of approximately 125 individuals. Hybrids were characterized by morphologies that most closely resembled their maternal parents based on chloroplast evidence. Studies of artificially synthesized and natural hybrids demonstrated that hybrid seed had very low germination rates and naturally occurring hybrids exhibited pollen sterility. Post-zygotic reproductive isolating mechanisms play a primary role in limiting gene exchange between co-occurring species and maintaining species integrity in areas of sympatry.