Data from: Systematics and evolution of inflorescence structure in the Tradescantia alliance (Commelinaceae)

The Tradescantia alliance (subtribes Tradescantiinae and Thyrsantheminae of tribe Tradescantieae, family Commelinaceae) comprises a group of closely related New World genera exhibiting considerable variation in morphological, life history, and genomic traits. Despite ecological and cytogenetic significance, phylogenetic relationships among genera and species remain uncertain. In particular, variation in inflorescence morphology has confounded classification and taxonomy. The presence of self compatible and incompatible species allowed us to test the hypothesis that self compatible species will have condensed inflorescences. We inferred phylogenetic relationships using two plastid loci (rpL16, trnL-trnF) for 85 taxa in Commelinaceae, with sampling focused in the Tradescantia alliance. Constraint tests supported only subtribe Tradescantiinae, Tripogandra and Tinantia as monophyletic, with Tripogandra nested within Callisia. We estimated ancestral states for both breeding system and inflorescence condensation and tested for a correlation. Inflorescence morphology, an important character for generic identification, is more labile than previously expected, with condensed inflorescences evolving twice with three subsequent reversals. Breeding system evolution is more complex, with many more switches between self compatibility and self incompatibility and more uncertainty in ancestral state estimates. While we did not find a correlation between self compatibility and inflorescence condensation, we propose additional floral and inflorescence characteristics that may have contributed to variation in breeding system.本研究涉及的紫鸭跖草类群（Tradescantia alliance）隶属于鸭跖草科（Commelinaceae）鸭跖草族（Tradescantieae）下的紫鸭跖草亚族（Tradescantiinae）与穗花鸭跖草亚族（Thyrsantheminae），包含一组亲缘关系紧密的新世界分布属类群，其形态、生活史及基因组特征均存在显著变异。尽管该类群具有重要的生态学与细胞遗传学研究价值，但属间与物种间的系统发育关系仍未明确。其中，花序形态的变异长期困扰着类群的分类与系统学研究。自交亲和与自交不亲和物种的共存，为我们验证"自交亲和物种将拥有短缩花序"这一假说提供了研究基础。本研究以鸭跖草科85个类群为研究对象，采样以紫鸭跖草类群为核心，利用两个质体基因位点（rpL16、trnL-trnF）推断其系统发育关系。约束性检验仅支持紫鸭跖草亚族、三蕊草属（Tripogandra）和田氏草属（Tinantia）为单系类群，且三蕊草属（Tripogandra）嵌套于吊竹梅属（Callisia）之内。本研究估算了繁育系统与花序短缩度的祖先性状状态，并检验了二者的相关性。作为属级鉴定的重要形态特征，花序形态的演化可塑性较此前预期更强：短缩花序独立演化两次，且随后发生了三次演化逆转。繁育系统的演化更为复杂，自交亲和与自交不亲和之间的转换事件更多，且祖先状态的估算存在更高的不确定性。尽管本研究未发现自交亲和性与花序短缩度之间存在显著相关性，但我们提出了若干可能参与调控繁育系统变异的其他花部与花序特征。