Comparative analysis of corolla shape transitions in the sister genera <i>Gesneria </i>and <i>Rhytidophyllum </i>(Gesneriaceae)

Convergence, the independent acquisition of similar phenotypes, is an important aspect of diversity that can provide valuable insights about the nature of evolutionary change. In plants, pollination syndromes - combinations of floral traits adapted to their pollinators - make good examples of convergence occurring on flowers. We used a comprehensive approach that includes cell morphology and transcriptomics to analyze the floral shape convergence of two pollination syndromes found in the sister genera <i>Gesneria </i>and <i>Rhytidophyllum </i>(Gesneriaceae), an Antillean group that contains approximately 81 species with different morphologies and pollination strategies varying in their degree of ecological specialization. Flower shape has already been found to play an important role in the evolution of this group, which shows many transitions between pollination strategies. We tested convergence in the corolla cell shapes and in gene expression for the pollination syndromes using (1) cell measurement statistical analysis (Phylogenetic Mixed Model) of mature petals and (2) a comparative transcriptomic approach that combined differential gene expression (DESEq2) and co-expression analysis (WGCNA) in genes expressed in specific regions of the petals. All analyses took the phylogenetic relationships of the species into account. We found convergent cellular anisotropy occurring in the distal regions of the petals within species of the same syndrome (form). We also found greater similarity in gene expression patterns occurring among species of the same syndromes than between more closely related species and produced a list of 203 genes potentially associated with convergent flower forms. The floral morphological convergence observed in the pollination syndromes of the investigated species is paralleled both at the cellular and expression levels. The results shown here amplify the background information of the Gesneriaceae family for future studies of convergence and floral form in the group.

趋同演化（Convergence）指独立获得相似表型的过程，是生物多样性的重要特征，可为演化改变的本质提供宝贵研究见解。在植物中，传粉综合征（pollination syndromes）——即适应传粉者的花部性状组合——是花部趋同演化的绝佳例证。我们采用包含细胞形态学与转录组学（transcriptomics）的综合研究方法，分析了姊妹属（sister genera）苦苣苔属（<i>Gesneria</i>）与卷萼苣苔属（<i>Rhytidophyllum</i>，苦苣苔科Gesneriaceae）内两类传粉综合征的花部形状趋同演化现象。该类群为安的列斯群岛分布类群，包含约81个形态各异、传粉策略生态特化程度各不相同的物种。已有研究证实，花形在该类群的演化过程中发挥关键作用，其传粉策略间存在多次演化转换。我们通过两种途径检验了两类传粉综合征在花冠细胞形态与基因表达层面的趋同性：（1）对成熟花瓣开展细胞测量的统计学分析（系统发育混合模型Phylogenetic Mixed Model）；（2）结合差异基因表达分析（DESeq2）与花瓣特定区域表达基因共表达分析（加权基因共表达网络分析WGCNA）的比较转录组学方法。所有分析均纳入了物种间的系统发育关系。研究发现，同一传粉综合征（花形）类群的物种，其花瓣远端区域存在趋同的细胞各向异性（anisotropy）。同时，相较于亲缘关系更近的物种，同一传粉综合征类群的物种间基因表达模式相似度更高，我们最终筛选得到203个潜在与趋同花形相关的基因。本研究观测到的受试类群传粉综合征花部形态趋同演化现象，在细胞与基因表达层面均得到了印证。本次研究结果丰富了苦苣苔科的相关背景资料，可为该类群后续的趋同演化与花形研究提供支撑。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于Gesneriaceae科中姐妹属Gesneria和Rhytidophyllum的花冠形状趋同进化研究，通过细胞形态学和转录组学方法分析传粉综合征下的花形变化。数据集包含正交表、计数矩阵和长度矩阵等原始数据，支持对花瓣细胞各向异性和基因表达趋同的统计与转录组分析，并识别出203个潜在相关基因，为植物进化生物学研究提供了重要资源。