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.

鸭跖草科（Commelinaceae）鸭跖草族（Tradescantieae）下的紫露草联盟（Tradescantia alliance）包含紫露草亚族（Tradescantiinae）与穗花鸭跖草亚族（Thyrsantheminae）两类群，由一系列亲缘关系密切的新世界属类群构成，其成员在形态特征、生活史与基因组性状上均存在显著变异。尽管该类群具备重要的生态学与细胞遗传学研究价值，但属间与种间的系统发育关系仍未明确。尤为棘手的是，花序形态的变异长期困扰着该类群的分类与系统学研究。该联盟中同时存在自交亲和（self compatibility）与自交不亲和（self incompatibility）物种，这为我们验证“自交亲和物种的花序更为紧凑”这一假说提供了研究基础。本研究以紫露草联盟类群为核心采样对象，对鸭跖草科85个类群的两个质体基因座（plastid loci）rpL16、trnL-trnF进行测序分析，以此推断其系统发育关系。约束检验结果仅支持紫露草亚族、三柱草属（Tripogandra）与银波草属（Tinantia）为单系类群，且三柱草属嵌套于锦竹草属（Callisia）内部。我们还对繁育系统（breeding system）与花序紧凑度两类性状开展了祖先状态（ancestral states）重建，并检验了二者的相关性。作为属级鉴定的关键形态性状，花序形态的演化可塑性较此前预期更强：紧凑花序独立起源两次，并伴随三次后续的演化逆转。繁育系统的演化则更为复杂，自交亲和与自交不亲和状态间的转换更为频繁，且祖先状态的推断存在更多不确定性。尽管本研究未发现自交亲和性与花序紧凑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性状。