Hybridization is a biological phenomenon increasingly recognized as an important evolutionary process in both plants and animals, as it is linked to speciation, radiation, extinction, range expansion and invasion, and allows for increased trait diversity in agricultural and horticultural systems. Estimates of hybridization frequency vary across taxonomic groups, but causes of this variation are unknown. Here, we ask on a global scale whether hybridization is linked to any of 11 traits related to plant life history, reproduction, genetic predisposition, and environment or opportunity. Given that hybridization is not evenly distributed across the plant tree of life, we use phylogenetic generalized least squares regression models and phylogenetic path analysis to detect statistical associations between hybridization and plant traits at both the family and genus levels. We find that perenniality and woodiness are each weakly associated with an increased frequency of hybridization in univariate analyses, but path analysis suggests that the direct linkage is between perenniality and increased hybridization (with woodiness having only an indirect relationship with hybridization via perenniality). Weak associations between higher rates of hybridization and higher outcrossing rates, abiotic pollination syndromes, vegetative reproductive modes, larger genomes, and less variable genome sizes are detectable in some cases but not others. We argue that correlational evidence at the global scale, such as that presented here, provides a robust framework for forming hypotheses to examine and test drivers of hybridization at a more mechanistic level.

中文翻译：

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植物杂交的相关性

杂交是一种生物现象，在植物和动物中日益被认为是重要的进化过程，因为它与物种形成，辐射，灭绝，范围扩大和入侵有关，并允许农业和园艺系统中性状的多样性增加。杂交频率的估计因分类组而异，但这种变化的原因尚不清楚。在这里，我们在全球范围内询问杂交是否与与植物生活史，繁殖，遗传易感性以及环境或机会有关的11个性状中的任何一个相关。由于杂交没有在整个生命树中平均分配，我们使用系统发育广义最小二乘回归模型和系统发育路径分析来检测家族和属水平上杂交与植物性状之间的统计关联。我们发现，在单变量分析中，多年生性和木本性均与杂交频率的增加弱相关，但是路径分析表明，多年生性和杂交性之间存在直接联系（木质性与通过多年生性与杂交仅具有间接关系）。在某些情况下，可检测到较高的杂交率与较高的异型率，非生物授粉综合症，营养繁殖方式，较大的基因组和较小的基因组大小之间的弱关联。我们认为，全球范围内的相关证据