Apomixis in angiosperms is asexual reproduction from seed. Its importance to angiospermous evolution and biodiversity has been difficult to assess mainly because of insufficient taxonomic documentation. Thus, we assembled literature reporting apomixis occurrences among angiosperms and transferred the information to an internet database (http://www.apomixis.uni-goettingen.de). We then searched for correlations between apomixis occurrences and well-established measures of taxonomic diversity and biogeography. Apomixis was found to be taxonomically widespread with no clear tendency to specific groups and to occur with sexuality at all taxonomic levels. Adventitious embryony was the most frequent form (148 genera) followed by apospory (110) and diplospory (68). All three forms are phylogenetically scattered, but this scattering is strongly associated with measures of biodiversity. Across apomictic-containing orders and families, numbers of apomict-containing genera were positively correlated with total numbers of genera. In general, apomict-containing orders, families, and subfamilies of Asteraceae, Poaceae, and Orchidaceae were larger, i.e., they possessed more families or genera, than non-apomict-containing orders, families or subfamilies. Furthermore, many apomict-containing genera were found to be highly cosmopolitan. In this respect, 62% occupy multiple geographic zones. Numbers of genera containing sporophytic or gametophytic apomicts decreased from the tropics to the arctic, a trend that parallels general biodiversity. While angiosperms appear to be predisposed to shift from sex to apomixis, there is also evidence of reversions to sexuality. Such reversions may result from genetic or epigenetic destabilization events accompanying hybridization, polyploidy, or other cytogenetic alterations. Because of increased within-plant genetic and genomic heterogeneity, range expansions and diversifications at the species and genus levels may occur more rapidly upon reversion to sexuality. The significantly-enriched representations of apomicts among highly diverse and geographically-extensive taxa, from genera to orders, support this conclusion.

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被子植物无融合生殖的分类学和生物地理学及相关的生物多样性特征

被子植物的无融合生殖是种子的无性繁殖。它对被子植物进化和生物多样性的重要性一直难以评估，主要是因为分类学文献不足。因此，我们收集了报告被子植物无融合生殖发生的文献，并将信息传输到互联网数据库 (http://www.apomixis.uni-goettingen.de)。然后，我们搜索了无融合生殖发生与分类多样性和生物地理学的完善措施之间的相关性。发现无融合生殖在分类学上广泛存在，没有明确的特定群体倾向，并且在所有分类学水平上都有性行为。不定胚是最常见的形式（148 属），其次是背孢（110）和双孢（68）。所有三种形式在系统发育上都是分散的，但这种分散与生物多样性的措施密切相关。在含无融合生殖的目和科中，含无融合生殖的属数与总属数呈正相关。一般来说，菊科、禾本科和兰科的含无融合生殖目、科和亚科比不含无融合生殖的目、科或亚科更大，即拥有更多的科或属。此外，发现许多包含无融合生殖的属具有高度的世界性。在这方面，62% 占据多个地理区域。从热带到北极，含有孢子体或配子体无融合生殖的属的数量减少，这一趋势与一般生物多样性相似。虽然被子植物似乎倾向于从有性转变为无融合生殖，但也有证据表明性行为会逆转。这种逆转可能由伴随杂交、多倍体或其他细胞遗传学改变的遗传或表观遗传不稳定事件引起。由于植物内遗传和基因组异质性的增加，物种和属水平的范围扩展和多样化可能会在恢复有性后更快地发生。从属到目，高度多样化和地域广泛的分类群中无融合生殖的显着丰富的表示支持了这一结论。