Valderrama Eugenio, Landis Jacob B, Skinner Dave, Maas Paul J M, Maas-van de Kramer Hiltje, André Thiago, Grunder Nikolaus, Sass Chodon, Pinilla-Vargas Maria, Guan Clarice J, Phillips Heather R, de Almeida Ana Maria Rocha, Specht Chelsea D
School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, NY, United States.
BTI Computational Biology Center, Boyce Thompson Institute, Ithaca, NY, United States.
Front Plant Sci. 2022 Sep 8;13:874322. doi: 10.3389/fpls.2022.874322. eCollection 2022.
Selection together with variation in floral traits can act to mold floral form, often driven by a plant's predominant or most effective pollinators. To investigate the evolution of traits associated with pollination, we developed a phylogenetic framework for evaluating tempo and mode of pollination shifts across the genus L., known for its evolutionary toggle between traits related to bee and bird pollination. Using a target enrichment approach, we obtained 957 loci for 171 accessions to expand the phylogenetic sampling of Neotropical . In addition, we performed whole genome resequencing for a subset of 20 closely related species with contrasting pollination syndromes. For each of these 20 genomes, a high-quality assembled transcriptome was used as reference for consensus calling of candidate loci hypothesized to be associated with pollination-related traits of interest. To test for the role these candidate genes may play in evolutionary shifts in pollinators, signatures of selection were estimated as across the identified candidate loci. We obtained a well-resolved phylogeny for Neotropical despite conflict among gene trees that provide evidence of incomplete lineage sorting and/or reticulation. The overall topology and the network of genome-wide single nucleotide polymorphisms (SNPs) indicate that multiple shifts in pollination strategy have occurred across , while also suggesting the presence of previously undetected signatures of hybridization between distantly related taxa. Traits related to pollination syndromes are strongly correlated and have been gained and lost in concert several times throughout the evolution of the genus. The presence of bract appendages is correlated with two traits associated with defenses against herbivory. Although labellum shape is strongly correlated with overall pollination syndrome, we found no significant impact of labellum shape on diversification rates. Evidence suggests an interplay of pollination success with other selective pressures shaping the evolution of the inflorescence. Although most of the loci used for phylogenetic inference appear to be under purifying selection, many candidate genes associated with functional traits show evidence of being under positive selection. Together these results indicate an interplay of phylogenetic history with adaptive evolution leading to the diversification of pollination-associated traits in Neotropical .
花部性状的选择与变异共同作用塑造花的形态，这通常由植物的主要或最有效的传粉者驱动。为了研究与传粉相关性状的进化，我们构建了一个系统发育框架，以评估整个 属传粉转变的节奏和模式，该属以其在与蜜蜂传粉和鸟类传粉相关性状之间的进化转换而闻名。使用目标富集方法，我们为171个种质获得了957个基因座，以扩大新热带地区 的系统发育抽样。此外，我们对20个具有不同传粉综合征的近缘物种的一个子集进行了全基因组重测序。对于这20个基因组中的每一个，一个高质量组装的转录组被用作参考，用于对假设与感兴趣的传粉相关性状相关的候选基因座进行一致性调用。为了测试这些候选基因在传粉者进化转变中可能发挥的作用，我们在已鉴定的候选基因座上估计了选择特征。尽管基因树之间存在冲突，提供了不完全谱系分选和/或网状化的证据，但我们还是获得了新热带地区 的一个解析良好的系统发育。全基因组单核苷酸多态性（SNP）的总体拓扑结构和网络表明，整个 属发生了多次传粉策略的转变，同时也表明在远缘类群之间存在以前未检测到的杂交特征。与传粉综合征相关的性状高度相关，并且在该属的整个进化过程中多次协同获得和丧失。苞片附属物的存在与两个与防御食草动物相关的性状相关。虽然唇瓣形状与总体传粉综合征密切相关，但我们发现唇瓣形状对多样化速率没有显著影响。有证据表明传粉成功与塑造 花序进化的其他选择压力之间存在相互作用。尽管用于系统发育推断的大多数基因座似乎处于纯化选择之下，但许多与功能性状相关的候选基因显示出正选择的证据。这些结果共同表明系统发育历史与适应性进化之间的相互作用导致了新热带地区 与传粉相关性状的多样化。
