Sistemática e biogeografia de Planaltina R.M. Salas & E.L. Cabral (Rubiaceae): um gênero endêmico do Cerrado brasileiro
Data
2021-09-20
Autores
Dutra, Letícia Lopes [UNIFESP]
Orientadores
Bruniera, Carla Poleselli [UNIFESP]
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O Cerrado é um domínio fitogeográfico brasileiro considerado um dos hotspots mundiais de biodiversidade. Nos últimos anos, estudos de táxons altamente diversos ou endêmicos do Cerrado têm se intensificado, visto que a perda da área nativa do domínio está acelerada, e consequentemente, de sua biodiversidade. Um gênero endêmico do Cerrado e que foi recentemente descrito é Planaltina, com quatro espécies: P. angustata, P. capitata, P. lanigera e P. myndeliana. Planaltina pertence à família Rubiaceae, e está inserido na tribo Spermacoceae, a qual possui distribuição pantropical, com aproximadamente 1250 espécies. As espécies de Planaltina foram transferidas recentemente de outros gêneros da tribo com base em caracteres morfológicos. Embora tenha sido feita uma revisão para o gênero, não foi comprovado seu monofiletismo e suas relações com outros gêneros da tribo não foram esclarecidas. Dessa forma, o presente estudo tem como objetivo principal a reconstrução da filogenia de Planaltina a fim de investigar as relações entre as espécies do gênero e grupos próximos, além de verificar possíveis sinapomorfias morfológicas para o gênero e sua história biogeográfica. Para inferir as relações filogenéticas foram utilizadas sequências do íntron rps16 do cloroplasto, e das regiões nucleares ITS e ETS de Planaltina e de outros gêneros do clado Spermacoce empregando a inferência Bayesiana. Foi gerada uma filogenia datada utilizando a calibração secundária, e com base nela foram realizadas reconstruções biogeográficas e dos estados ancestrais de caracteres. Em todas as análises filogenéticas, Planaltina emergiu como um grupo monofilético, sendo o clado formado por P. angustata e P. myndeliana grupo-irmão do clado formado por P. capitata e P. lanigera. Algumas espécies de Hexasepalum e Ernodea emergiram como prováveis grupos-irmãos de Planaltina. A reconstrução dos estados ancestrais de caracteres inferiu que o fruto tipo cápsula, a deiscência septífraga longitudinal e o grão de pólen com perfurações espessadas na exina podem ser consideradas sinapomorfias de Planaltina. A origem do gênero data de 3.03 Ma (HPD 95% = 4.38 – 1.68), entre o Plioceno e o Pleistoceno inferior. As espécies de Planaltina emergiram em simpatria na super-bioregião do Cerrado, tendo P. capitata e P. lanigera se dispersado para a super-bioregião do Espinhaço/Mantiqueira enquanto P. angustata e P. myndeliana permaneceram com distribuição restrita a super-bioregião do Cerrado.
The Cerrado is a Brazilian phytogeographic domain considered one of the world's biodiversity hotspots. In recent years, studies of highly diverse or endemic taxa of the Cerrado were intensified, as the loss of the domain's native area is accelerated, and consequently, its biodiversity. A genus endemic from the Cerrado and that has been recently described is Planaltina, with four species: P. angustata, P. capitata, P. lanigera and P. myndeliana. Planaltina belongs to the Rubiaceae family, and is inserted in the tribe Spermacoceae, which has a pantropical distribution, with approximately 1250 species. Planaltina species were recently transferred from other genera of the tribe based on morphological characters. Although a review for the genus has been carried out, its monophyly has not been proven and its relationships with other genera of the tribe have not been clarified. Thus, the present study has a main objective the reconstruction of the Planaltina phylogeny in order to investigate the relationships between the species of the genus and related groups, to identify possible morphological synapomorphies of the genus and its biogeographical history. To infer the phylogenetic relationships, sequences from the chloroplast intron rps16, and from the nuclear regions ITS and ETS of Planaltina and other genera of the Spermacoce clade were used for a Bayesian inference. A dated phylogeny was generated using secondary calibration, and based on it, ancestral character state reconstructions and biogeographic analysis were performed. In all phylogenetic analyses, Planaltina emerged as a monophyletic group, with the clade formed by P. angustata and P. myndeliana sister to the clade formed by P. capitata and P. lanigera. Species of Hexasepalum and Ernodea emerged as probable sister groups of Planaltina. The reconstruction of ancestral character states inferred that the capsule, the longitudinal septifragal dehiscence and pollen grains with thickened perforations in the exine can be considered Planaltina synapomorphies. The origin of the genus dates back to 3.03 Ma (95% HPD = 4.38 – 1.68), between the Pliocene and the Lower Pleistocene. Planaltina species emerged in sympatry in the Cerrado super-bioregion, with P. capitata and P. lanigera dispersing to the Espinhaço/Mantiqueira super-bioregion while P. angustata and P. myndeliana remained with restricted distribution to the super-bioregion of Cerrado.
The Cerrado is a Brazilian phytogeographic domain considered one of the world's biodiversity hotspots. In recent years, studies of highly diverse or endemic taxa of the Cerrado were intensified, as the loss of the domain's native area is accelerated, and consequently, its biodiversity. A genus endemic from the Cerrado and that has been recently described is Planaltina, with four species: P. angustata, P. capitata, P. lanigera and P. myndeliana. Planaltina belongs to the Rubiaceae family, and is inserted in the tribe Spermacoceae, which has a pantropical distribution, with approximately 1250 species. Planaltina species were recently transferred from other genera of the tribe based on morphological characters. Although a review for the genus has been carried out, its monophyly has not been proven and its relationships with other genera of the tribe have not been clarified. Thus, the present study has a main objective the reconstruction of the Planaltina phylogeny in order to investigate the relationships between the species of the genus and related groups, to identify possible morphological synapomorphies of the genus and its biogeographical history. To infer the phylogenetic relationships, sequences from the chloroplast intron rps16, and from the nuclear regions ITS and ETS of Planaltina and other genera of the Spermacoce clade were used for a Bayesian inference. A dated phylogeny was generated using secondary calibration, and based on it, ancestral character state reconstructions and biogeographic analysis were performed. In all phylogenetic analyses, Planaltina emerged as a monophyletic group, with the clade formed by P. angustata and P. myndeliana sister to the clade formed by P. capitata and P. lanigera. Species of Hexasepalum and Ernodea emerged as probable sister groups of Planaltina. The reconstruction of ancestral character states inferred that the capsule, the longitudinal septifragal dehiscence and pollen grains with thickened perforations in the exine can be considered Planaltina synapomorphies. The origin of the genus dates back to 3.03 Ma (95% HPD = 4.38 – 1.68), between the Pliocene and the Lower Pleistocene. Planaltina species emerged in sympatry in the Cerrado super-bioregion, with P. capitata and P. lanigera dispersing to the Espinhaço/Mantiqueira super-bioregion while P. angustata and P. myndeliana remained with restricted distribution to the super-bioregion of Cerrado.