Molecular insights to the genealogical relationships in the genus Ceiba (Malvaceae)

• Ano de defesa: 2023
• Autor(a) principal: Ugwor, Emmanuel Ifeanyichukwu
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Bioquímica Aplicada
• Palavras-chave em Português: Plantas - Variação; Marcadores genéticos; Ceiba; Malvaceae; CIENCIAS BIOLOGICAS::GENETICA::GENETICA VEGETAL
• Link de acesso: https://locus.ufv.br/handle/123456789/32729; https://doi.org/10.47328/ufvbbt.2023.107

The geographical and morphological diversity among the congeners of Ceiba makes the genus a suitable model to appraise the evolutionary dynamics of arboreal flora in the Neotropical realm. This study sought to investigate the genealogical relationships of the different species within the genus Ceiba. Sequences of the nuclear internal transcribed spacer (ITS) and chloroplast gene (trnT-trnL, intron trnL, trnS-trnG, matK, and trnH-psbA) regions from 15 congeners of Ceiba were analysed using Bayesian inference and Median Joining Network, with Pseudobombax as the outgroup. Results indicate that Ceiba and Pseudobombax were separated into two distinct lineages. However, based on ITS data alone, the genus Ceiba is not monophyletic, with specimens of Ceiba crispiflora and Ceiba ventricosa included in the outgroup, most likely due to incomplete lineage sorting or a hybridisation event. The chloroplast genes- based tree recovered Ceiba as monophyletic, but the phylogenetic relationships were unclear as the tree exhibited relatively low support (posterior probability < 90%) for all major nodes. Phylogenetic analysis of the combined ITS and chloroplast genes dataset produced a better resolution of the relationships within Ceiba, with the congeners divided into three main clades. The first clade brought together specimens of Ceiba speciosa, Ceiba samauma, and Ceiba pentandra, while the second comprised specimens collected outside Brazil (Ceiba acuminata, Ceiba aesculifolia, and Ceiba schottii). The third clade was the largest, most diversified, and likely originated from the Atlantic Forest, transitioning into the Cerrado and Mesoamerican subregions. The consensus tree (from the combined dataset) presented a pattern of phylogeographic congruence, in which the phylogenetic placement of the members of distinct clades and subclades paralleled the geographic distribution of the specimens. Our results provide further insights into the genealogical relationships among Ceiba species and contribute to the existing knowledge on the processes maintaining the Neotropical diversity. Keywords: Ceiba; Malvaceae; Neotropics; Phylogenetics; Phylogeography