克隆植物中的同步雌雄异熟现象研究进展

A Review of Synchronous Dichogamy in Clonal Plants

很多植物具有克隆生长的习性,克隆生长对植物的交配格局和长期进化具有重要意义。克隆生长通常伴随有较多的花展示,但花粉的有效散布又会受到克隆规模的限制,进而形成分株间的同株异花授粉,造成近交衰退或花粉贴现。同步雌雄异熟是雌雄异熟的一种特殊形式,同时满足2个条件:1)单个花朵内为雌雄异熟;2)不同花朵间在同一时段内处于同一性别阶段。该种现象可以有效阻止分株内或分株间同株异花授粉,并可能是一种进化选择的特殊繁殖保障机制。目前其在克隆植物中的表现形式和作用机理尚未明确。在梳理近20a来相关文献的基础上,以克隆植物中的同步雌雄异熟现象为核心议题,结合克隆植物种群结构的特殊性探讨该现象对克隆植物的进化意义,并对该现象的类群分布情况、研究方法以及主要结论进行了分析,认为未来的研究应该注重4个方面:1)采用统一的同步性度量体系,并使其扩展到对雌性和雄性阶段的分别描述;2)重视目标物种交配系统的研究,尤其是自交亲和性的重要意义;3)重视克隆多样性格局对交配过程的影响,并采取恰当的方法予以量化;4)加强风媒、水媒等非生物因素传粉方式对克隆植物交配过程影响的研究。

Clonal growth is a common trait in plants.It has profound effect in the mating pattern and long term evolution of plant population but is currently seldom explored.Clonal growth is usually associated with mass flowering,restricted pollen dispersal,and geitonogamous self-pollination,which can result in inbreeding depression and pollen discounting.However,mating costs can be reduced by differences in the relative timing of female and male function(dichogamy).Synchronous dichogamy,a subtype of dichogamy,fulfills:1)dichogamy within one flower;2)having the same sexual phase between different flowers at a given time.It’s a potentially effective mechanism to limit inter/intra ramet geitonogamy,as well as a unique way to provide reproductive assurance.In this review,we surveyed related literatures of the past two decades.We focused on the concepts and evolutionary significance of synchronous dichogamy in clonal plants.A summary of acquired information on systematic distribution,research methods and ecological significance of synchronous dichogamy in clonal plants was presented.We recommend future research efforts to address such aspects:1)universal and effective metrics to evaluate synchronicity of different sex function separately;2)the ecological implication of selfing compatibility in synchronous dichogamy;3)the interaction of clonal diversity and mating patterns with synchronicity taken into consideration;4)abiotic pollination and synchronous dichogamy in clonal plants.