Fenologia e biologia reprodutiva de espécies de Piper (Piperaceae) em floresta estacional semidecídua: aspectos ecológicos e filogenéticos
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Data
2017-02-21
Autores
Silva, Adriano Valentin da [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Estudamos diferentes aspectos relacionados à biologia reprodutiva de Piper, tendo como plano de fundo o parentesco filogenético entre espécies coocorrentes e utilizando diferentes níveis de amostragem, desde a taxocenose até a flor. No capítulo 1, avaliamos a fenologia reprodutiva de 17 espécies de Piper em uma floresta estacional semidecídua para verificar se o clima e o parentesco filogenético estão associados às respostas fenológicas dessas espécies coocorrentes. Apenas a floração apresentou sinal filogenético e foi estacional. A frutificação foi influenciada por fatores abióticos, enquanto a floração teve uma influência compartilhada de fatores abióticos e das restrições filogenéticas. Assim, verificamos que mesmo em ambientes estacionais, pode haver influência da filogenia nos eventos reprodutivos. No capítulo 2, avaliamos o sistema de polinização e testamos se os caracteres florais e dos polinizadores estão correlacionados para verificar se os polinizadores podem ter mediado a diversificação floral em espécies fenotipicamente generalistas. As espécies são entomófilas e foram visitadas por 46 espécies de abelhas, besouros, mirídeos e moscas. Portanto, são ecológica e funcionalmente generalistas. Não houve correlação entre os caracteres florais e os dos visitantes florais, o que sugere que os caracteres analisados não representam adaptações aos polinizadores. Outros fatores, p. ex. ambientes-chave, devem estar relacionados com a diversificação do gênero. No capítulo 3, determinamos a expressão sexual das espécies, com enfoque na funcionalidade das flores ao longo da antese, para verificar se existem variações do hermafroditismo, caráter considerado como universal nas espécies neotropicais do gênero. Observamos variações dessa expressão sexual em quase 25% das espécies aqui estudadas. E no capítulo 4, determinamos se existe um padrão de liberação de pólen e exposição estigmática em espécies neotropicais de Piper, independentemente dos números de estames e carpelos e da sexualidade da flor. A dinâmica dos eventos florais foi semelhante entre as espécies: a exposição e senescência estigmática ocorreu de forma sequencial e gradual em sentido basípeto e a liberação de pólen foi assincrônica e sequencial. Como as espécies aqui estudadas pertencem a diferentes clados do gênero, essas características devem ser um padrão para as espécies neotropicais de Piper.
We studied different aspects related to the reproductive biology of Piper, having as background the phylogenetic relationship among the species and using different levels of sampling, from the taxocoenosis to the flower. In chapter 1, we evaluated the reproductive phenology of 17 Piper species in a semideciduous seasonal forest to verify whether climate and phylogenetic relationshipare associated with the phenological responses of these co-occurring species. Only flowering showed phylogenetic signal and was seasonal. Fruiting was influenced by abiotic factors, whereas flowering had a shared influence of abiotic factors and phylogenetic constraints. Thus, even in seasonal environments, there may be an influence of phylogeny on reproductive events. In chapter 2, we evaluated the pollination system and tested whether floral and pollinator characters are correlated to verify whether pollinators may have mediated floral diversification in phenotypically generalist species. The species are entomophilous and were visited by 46 species of bees, beetles, mirids and flies. So they are ecologically and functionally generalist. There was no correlation between floral characters and floral visitors’ characters, which suggests that the analyzed characters do not represent adaptations to the pollinators. Other factors, e.g. key environments, should be related to diversification of this genus. In chapter 3, we determined the sexual expression of species, focusing on the functionality of flowers throughout the anthesis, to verify whether there are variations of hermaphroditism, a character considered as universal in the Neotropical species of the genus. We observed variations of this sexual expression in almost 25% of the species studied here. And in chapter 4, we determined whether there is a pattern of pollen release and stigmatic exposure in Neotropical Piper species, independently of the number of stamens and carpels, and flower sexuality. The dynamic of floral events was similar among species: the exposure and senescence of stigmas was sequential and gradual in a basipetal direction, and pollen release was asynchronous and sequential. As the analyzed species belong to different clades of the genus, these characteristics should be a pattern for Neotropical Piper species.
We studied different aspects related to the reproductive biology of Piper, having as background the phylogenetic relationship among the species and using different levels of sampling, from the taxocoenosis to the flower. In chapter 1, we evaluated the reproductive phenology of 17 Piper species in a semideciduous seasonal forest to verify whether climate and phylogenetic relationshipare associated with the phenological responses of these co-occurring species. Only flowering showed phylogenetic signal and was seasonal. Fruiting was influenced by abiotic factors, whereas flowering had a shared influence of abiotic factors and phylogenetic constraints. Thus, even in seasonal environments, there may be an influence of phylogeny on reproductive events. In chapter 2, we evaluated the pollination system and tested whether floral and pollinator characters are correlated to verify whether pollinators may have mediated floral diversification in phenotypically generalist species. The species are entomophilous and were visited by 46 species of bees, beetles, mirids and flies. So they are ecologically and functionally generalist. There was no correlation between floral characters and floral visitors’ characters, which suggests that the analyzed characters do not represent adaptations to the pollinators. Other factors, e.g. key environments, should be related to diversification of this genus. In chapter 3, we determined the sexual expression of species, focusing on the functionality of flowers throughout the anthesis, to verify whether there are variations of hermaphroditism, a character considered as universal in the Neotropical species of the genus. We observed variations of this sexual expression in almost 25% of the species studied here. And in chapter 4, we determined whether there is a pattern of pollen release and stigmatic exposure in Neotropical Piper species, independently of the number of stamens and carpels, and flower sexuality. The dynamic of floral events was similar among species: the exposure and senescence of stigmas was sequential and gradual in a basipetal direction, and pollen release was asynchronous and sequential. As the analyzed species belong to different clades of the genus, these characteristics should be a pattern for Neotropical Piper species.
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Palavras-chave
Andromonoicia, Entomofilia, Protoginia incompleta, Sinal filogenético