Asexual organisms usually have larger, and in the Northern Hemisphere, more northern distributions than their sexual relatives. This phenomenon, called geographical parthenogenesis, has been attributed to predispositions in certain taxa, advantages of polyploidy and/or hybrid origin, advantages of uniparental reproduction, introgression of apomixis into sexuals, niche differentiation of clones, and biotic interactions. Here we focus on the role of uniparental reproduction in colonisation, and the importance of different developmental pathways, i.e. autonomous apomixis which does not require pollination and fertilisation of endosperm nuclei for successful seed set, and pseudogamous apomixis which does. A literature survey suggests that geographical parthenogenesis occurs frequently in species with autonomous apomixis, while the correlation with pseudogamy is poorly documented. However, taxonomic patterns (e.g. predominance of Asteraceae) and also methodological bias may influence estimates of frequencies of geographical parthenogenesis. We demonstrate that a flow cytometric seed screen (FCSS) is a powerful method for assessing pseudogamous vs. autonomous apomixis. We show that population genetic studies provide insights into the genetic diversity of apomicts, but do not give strong support for uniparental reproduction being the only explanation of geographical parthenogenesis. Molecular studies help elucidate the evolutionary and biogeographical history of apomictic complexes, and we conclude that multidisciplinary studies are needed to understand fully the phenomenon of geographical parthenogenesis.

中文翻译：

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了解无融合生殖植物的地理分布：多元化方法的案例


无性生物通常比它们的有性近亲有更大的范围，并且在北半球的分布也更靠北。这种现象被称为地理单性生殖，归因于某些类群的倾向、多倍体和/或杂交起源的优势、单亲繁殖的优势、无融合生殖向有性生殖的渗入、克隆的生态位分化和生物相互作用。在这里，我们重点关注单亲繁殖在定殖中的作用，以及不同发育途径的重要性，即不需要胚乳核授粉和受精就能成功结籽的自主无融合生殖，以及需要的假受精无融合生殖。文献调查表明，地理单性生殖经常发生在具有自主无融合生殖的物种中，而与假受精的相关性却鲜有记录。然而，分类模式（例如菊科的优势）和方法学偏差可能会影响地理单性生殖频率的估计。我们证明，流式细胞仪种子筛选（FCSS）是评估假受精与自主无融合生殖的有效方法。我们表明，群体遗传学研究提供了对无性生殖遗传多样性的见解，但并没有强有力地支持单亲繁殖是地理单性生殖的唯一解释。分子研究有助于阐明无融合生殖复合体的进化和生物地理历史，我们得出的结论是，需要多学科研究来充分理解地理孤雌生殖现象。