PREMISE Although polyploidy has been studied since the early 1900s, fundamental aspects of polyploid ecology and evolution remain unexplored. In particular, surprisingly little is known about how newly formed polyploids (neopolyploids) become demographically established. Models predict that most polyploids should go extinct within the first few generations as a result of reproductive disadvantages associated with being the minority in a primarily diploid population (i.e., the minority cytotype principle), yet polyploidy is extremely common. Therefore, a key goal in the study of polyploidy is to determine the mechanisms that promote polyploid establishment in nature. Because premating isolation is critical in order for neopolylpoids to avoid minority cytotype exclusion and thus facilitate establishment, we examined floral morphology and three common premating barriers to determine their importance in generating reproductive isolation of neopolyploids from diploids. METHODS We induced neopolyploidy in Trifolium pratense and compared their floral traits to the diploid progenitors. In addition to shifts in floral morphology, we examined three premating barriers: isolation by self-fertilization, flowering-time asynchrony, and pollinator-mediated isolation. RESULTS We found significant differences in the morphology of diploid and neopolyploid flowers, but these changes did not facilitate premating barriers that would generate reproductive isolation of neopolyploids from diploids. There was no difference in flowering phenology, pollinator visitation, or selfing between the cytotypes. CONCLUSIONS Our results indicate that barriers other than the ones tested in this study-such as geographic isolation, vegetative reproduction, and pistil-stigma incompatibilities-may be more important in facilitating isolation and establishment of neopolyploid T. pratense.

中文翻译：

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全基因组复制不会促进三叶草中常见的生殖隔离模式

前提 尽管自 1900 年代初就开始研究多倍体，但多倍体生态学和进化的基本方面仍未得到探索。特别是，令人惊讶的是，关于新形成的多倍体（新多倍体）如何在人口统计学上建立起来的知之甚少。模型预测大多数多倍体应该在最初的几代内灭绝，这是由于与主要二倍体种群中的少数群体相关的生殖劣势（即少数细胞型原则），但多倍体极为普遍。因此，多倍体研究的一个关键目标是确定在自然界中促进多倍体建立的机制。因为前分离对于新多倍体避免少数细胞型排斥从而促进建立至关重要，我们检查了花卉形态和三种常见的预交障碍，以确定它们在产生新多倍体与二倍体生殖隔离方面的重要性。方法我们在三叶草中诱导了新多倍体，并将它们的花性状与二倍体祖先进行了比较。除了花的形态变化之外，我们还检查了三个交配前的障碍：通过自体受精隔离、开花时间不同步和传粉媒介介导的隔离。结果我们发现二倍体和新多倍体花的形态存在显着差异，但这些变化并没有促进会产生新多倍体与二倍体生殖隔离的预交障碍。细胞型之间的开花物候、传粉者访问或自交没有差异。