Traços florais e filogenia em espécies lenhosas do cerrado
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Data
2013-02-26
Autores
Gonçalves, Carolina Stella [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Conjuntos de traços refletindo adaptações a certos polinizadores são conhecidos como síndromes de polinização. Estudos sobre morfologia floral e síndromes de polinização fundamentaram o nosso conhecimento sobre as interações planta-polinizador, mas ainda sabemos pouco sobre como as formas florais mudaram na evolução, lacuna esta que pode ser preenchida com abordagens filogenéticas. Estudamos traços florais, síndromes de polinização, e filogenia de espécies lenhosas de cerrado respondendo às perguntas: (1) As síndromes de polinização são consistente?; (2) Quais as características associadas a cada síndrome?; (3) Os traços florais apresentam sinal filogenético?; (4) Há padrões globais e locais na filogenia?; (5) A diversidade de traços está expressa em um ou em poucos nós da filogenia?; (6) A diversidade de traços está agrupada perto da raiz ou das folhas da árvore? Respondendo às primeira e segunda perguntas, corroboramos a existência de duas síndromes de polinização mais frequentes: abelhas, associada aos maiores diâmetros da base da corola, e insetos pequenos, associada às maiores concentrações de néctar. À terceira pergunta, verificamos que todas os traços florais apresentam sinal filogenético, a maioria deles com valor negativo. À quarta questão, encontramos tanto padrões globais como locais da evolução dos traços. Finalmente, às quinta e sexta questões, descobrimos que a diversidade de traços está concentrada em alguns nós ao longo da árvore filogenética. As interações entre flores e polinizadores parecem ter tido um papel importante na diversificação das plantas do cerrado. A diversidade de traços florais pode ser atribuída, em parte, à adaptação das angiospermas aos primeiros polinizadores do Cretáceo e, em parte, às adaptações ao ambiente de polinização cerrado
Sets of floral traits reflecting adaptations to certain pollinators are known as “pollination syndromes”. Studies on floral morphology and pollination syndromes underlied our knowledge on plant-pollinator interactions, but there is still little evidence as to how floral forms have shifted during the evolutionary time, a gap that could be filled with phylogenetic approaches. We studied floral traits, pollination syndromes, and phylogeny of cerrado woody species answering the questions: (1) Are pollination syndromes consistent? (2) Which trait values are associated to each syndrome?; (3) Do floral traits present phylogenetic signal?; (4) Are there global and local phylogenetic structures?; (5) Is trait diversity expressed in one or few nodes of the phylogeny?; (6) Is trait diversity clustered near the root or near the tips of the tree? For the first and second questions, we corroborated the existence of two major pollination syndromes: “bees”, associated with the higher corolla base diameter; and “small generalist insects”, associated with higher nectar concentration. For the third question, we found that all of the traits presented phylogenetic signal, most of them with negative value. For the fourth, we encountered both global and local patterns of trait evolution. And, finally, for the fifth and sixth questions, we found that trait diversity is skewed through few nodes through the phylogenetic tree. We postulate that, in the cerrado, interaction between flowers and their pollinators seems to has played an important rule in angiosperm diversification. Floral traits diversity may be atributed partly to early angiosperm radiation in the mid-Cretaceous, and partly to adaptations to the cerrado pollination environment
Sets of floral traits reflecting adaptations to certain pollinators are known as “pollination syndromes”. Studies on floral morphology and pollination syndromes underlied our knowledge on plant-pollinator interactions, but there is still little evidence as to how floral forms have shifted during the evolutionary time, a gap that could be filled with phylogenetic approaches. We studied floral traits, pollination syndromes, and phylogeny of cerrado woody species answering the questions: (1) Are pollination syndromes consistent? (2) Which trait values are associated to each syndrome?; (3) Do floral traits present phylogenetic signal?; (4) Are there global and local phylogenetic structures?; (5) Is trait diversity expressed in one or few nodes of the phylogeny?; (6) Is trait diversity clustered near the root or near the tips of the tree? For the first and second questions, we corroborated the existence of two major pollination syndromes: “bees”, associated with the higher corolla base diameter; and “small generalist insects”, associated with higher nectar concentration. For the third question, we found that all of the traits presented phylogenetic signal, most of them with negative value. For the fourth, we encountered both global and local patterns of trait evolution. And, finally, for the fifth and sixth questions, we found that trait diversity is skewed through few nodes through the phylogenetic tree. We postulate that, in the cerrado, interaction between flowers and their pollinators seems to has played an important rule in angiosperm diversification. Floral traits diversity may be atributed partly to early angiosperm radiation in the mid-Cretaceous, and partly to adaptations to the cerrado pollination environment
Descrição
Palavras-chave
Ecologia do cerrado, Ecologia vegetal, Plantas dos cerrados, Cerrados, Filogenia, Polinização, Flores - Morfologia, Cerrado ecology
Como citar
GONÇALVES, Carolina Stella. Traços florais e filogenia em espécies lenhosas do cerrado. 2013. 69 f. Dissertacao (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2013.