克隆生长是被子植物最常见的无性繁殖方式，其生态和进化意义受到了广泛的关注。植物克隆生长与有性繁殖通常相伴进行，产生较大的花展示与复杂的克隆空间结构，对有性繁殖尤其是交配系统产生影响，共同决定植物的适合度。已有研究大多认为随着克隆分株数量增多，同株异花授粉水平会相应提高，导致自交率的增大或产生花粉阻塞效应，进而降低植物的适合度。但先前的研究关心的是克隆大小怎样影响植物的适合度，而没有考察繁殖资源投入相同时，花朵集生于一个花序上与花朵分散在不同分株上对适合度的影响差异，同时很少研究生态因子对同株异花授粉的影响。近期研究发现，当花朵数量相同时，如果花内雌雄功能同熟，克隆生长不仅不会增加反而可能降低同株异花授粉并提高花粉输出。此外，关于体细胞突变累积的研究也表明同株异花自交后代的适合度可能随着亲本花朵距离增加而上升，由于克隆生长习性导致在分株之间积累的体细胞突变存在一定差异，因而克隆生长能部分降低近交衰退带来的适合度损失。因此，本文以密集型克隆植物草乌（Aconitum kusnezoffii Reichb.）为研究对象，开展以下几个方面的研究，全面解析克隆生长对植物交配系统的影响。1）与非克隆方式相比，克隆生长对同株异花授粉有怎样的影响？2）克隆大小对同株异花授粉有怎样的影响？3）在不同环境下，克隆生长对同株异花授粉的影响可能会有怎样的改变？4）克隆植物体细胞突变累积对交配系统有怎样的影响？ 在北京小龙门种群利用人工捆绑花序操作构建大花序，开展传粉生物学观察和微卫星标记分析，比较克隆与非克隆生长方式的适合度差异。结果表明，在花总量保持一致的情况下，与大量花朵集生在同一花序上相比，克隆生长将等量花朵分散在若干分株上的花资源空间配置模式提高了对传粉者的吸引力，访花频率平均提高了50%，同时传粉者单次访花数量占克隆总花数的比例降低了13%；如果花朵同时接收和输出花粉，这种现象可以降低植株内同株异花授粉的发生几率。由于红光熊蜂自下而上访问草乌的直立花序，克隆生长打乱了传粉者的固有的移动规律，降低了雌雄异熟对同株异花授粉的限制作用，提高了自交率。 结合野外花期观测与室内微卫星标记分析，通过亲本分析的手段衡量克隆大小对雌性和雄性适合度的影响。结果表明，当每株植株每天产生超过40朵花时，草乌自交率显著提高，但提高花展示水平对花粉输出的影响不如增加开花分株数量明显。进一步结合种群内植株开花动态分析表明，雄性阶段花朵比例的增加在提高自交率的同时降低了花粉输出，种群花期末开花的克隆结籽率显著下降，花粉输出没有表现出明显的上升。 不同环境中克隆生长对同株异花授粉的影响研究表明，光照强度较弱的种群中草乌的花展示水平与传粉者数量显著降低，生活在郁闭环境中的草乌比生活在开放环境中的个体增加了超过50%的花蜜产量，通过提高传粉者回报的方式提高了传粉者访花比例及访花时长，并最终导致郁闭环境中草乌结籽率较开放环境提高了5%，种群水平和家系水平的自交率都显著增加。 开展人工授粉实验评估体细胞突变累积对草乌交配系统的影响，结果表明，长期的克隆生长可能由于累积了大量体细胞突变，降低了配子尤其是雄性配子的数量及活力，胚珠数量虽然没有表现出随克隆大小上升的下降趋势，但是作为母本时植株繁殖成功率却同作为父本时一样表现出了显著的下降。同时，克隆内部的体细胞突变累积通过严重的近交衰退降低了近距离同株异花自交的繁殖成功率，使得花序内同株异花自交结籽率比远距离花序间同株异花自交降低了20%。 综上所述，在相同花资源投入情景下，与非克隆生长方式相比，克隆生长可能通过增大对传粉者的吸引能力而促进花粉输出，但由于草乌雄性先熟，雌雄性别功能存在一定程度的分离，克隆生长并没有降低自交率，这与先前理论预期一致。克隆习性出现之后，随着克隆分株增多，自交率相应增加，也与先前研究结果一致。但本论文利用亲本分析手段揭示了随着克隆分株增多，雄性适合度（花粉输出）呈现出了先增加后降低的趋势。而且从开花物候的角度展开了对适合度影响的分析，揭示了随开花进程自交率先增加后降低的模式。不同环境下种群间的比较分析表明，克隆生长对植物交配系统的影响会随着生态因子的改变而改变。由于体细胞突变累积，随着克隆分株增多，雄性生育力表现出了一定程度的降低；但克隆生长使得克隆内不同分株共享相同体细胞突变的概率降低，因而分株间同株异花授粉导致的近交衰退程度低于花内自交或分株内同株异花自交。

Clonal plant species account for 80% angiosperm species, which reproduce sexually and asexually simultaneously. It has been widely thought that clonal growth could impact aspects of plant sexual reproduction, especially mating system. Generally, clonal growth is thought to reduce female reproductive success, owing to among-flower self-pollination (geitonogamy), especially in clonal species with clumped architecture. However, recent researches suggested that pollinators often visit fewer flowers on plants with multiple ramets than on plants with a single inflorescence with the same total number of flowers. As a consequence, clonality can promote pollination quality without increasing geitonogamy when flowers simultaneously receive and donate pollen. Besides, there is growing evidence that the accumulation of somatic mutation may result in lower fitness of autogamous offspring relative to geitonogamous offspring. So, in this study we evaluated the consequences of clonal growth on plant mating system in a clumped-clonal plant, Aconitum kusnezoffii. Specifically, we focused on the four questions. 1) Does clonal growth result in more geitonogamy compared with non-clonal plants when same amount of resources invest into floral display? 2) How will the geitonogamy change with the increase of clone size? 3) To what extent will the geitonogamy change in populations with different light environments? 4) What are the effects of accumulation of somatic mutation on male and female fertility, and difference between within- and among-ramet geitonogamous depression? To compare the reproductive success between clonal and non-clonal growth forms, we tied two ramets together to produce a single large inflorescence in a natural population. Compared with single large inflorescence, clonal growth with inflorescences on separate ramets increased pollinator attraction by 50% as well as decrease floral visiting proportion by 13% per bout. The visiting behavior has the potential to promote the pollen export and hence enhance the male fitness in plants with clonal growth. Selfing rate was higher for clonal plants because the geitonogamous pollination was enhanced by pollinators visiting pollen-presenting flowers before those with receptive stigmas in this dichogamous plant. Parentage analyses and phenological observation were conducted to evaluate the female and male fitness with clone size. Higher selfing rate was associated with increased floral display when flower number was larger than 40. However, pollen export was influenced by clone size but not floral display. Moreover, lower pollen export and higher selfing rate were associated with the increase of the proportion of male-phase flower. Both seed set and pollen export decline at the end of population flowering. Effects of clonal growth on geitonogamy were compared between in sunny and shaded populations. Floral display and pollinator abundance were significantly reduced in shaded populations. However, nectar production in shaded populations was 50% more than in sunny populations, which prolonged pollinator visiting duration and increased the proportion of visited flower per bout. As a consequence, seed set in shaded populations increased by 5%, but multilocus selfing rate was higher. Finally, hand pollination experiments were conducted to assess the effects of accumulation of somatic mutation on fitness of clonal plants. The number and fertility of male gametes were negatively correlated with clone size, while the ovule number did not correlated with clone size. Seed set of geitonogamy within ramets reduced by 20% compared with geitonogamy among ramets. In conclusion, this research showed that clonal growth can enhance the attractions to pollinators and may facilitate pollen export when the same resource was invested in floral display. However, clonal growth did not reduce selfing rate in this protandrous species, which was consistent with the recent expectations on the evolution of plant clonality. With the increase of clone size or floral display, selfing rate increased. This results was also consistent with the widely recognized trend. However, beyond the previous researches, this study revealed that the selfing rate increased first and then decreased with the process of flowering in populations, and that the male fitness increased and then decreased with clone size in clumped clonal plants. The further analyses demonstrated the ecology of geitonogamy in shaded and sunny populations. Furthermore, this study evidenced the reduced male fertility with clone size and more serious within-ramet geitonogamous depression relative to among-ramet geitonogamous depression.