Fenologia reprodutiva, distribuição espacial e frugivoria em Rhipsalis (Cactaceae)
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Data
2009-03-05
Autores
Guaraldo, André de Camargo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As epífitas são responsáveis por grande parte da diversidade vegetal das florestas neotropicais. São também importantes para a diversidade faunística dessas regiões, pois fornecem recursos alimentares (e.g., flores, frutos e sementes) e micro-ambientes propícios à sobrevivência de vários animais. Rhipsalis (Cactaceae) é um gênero de plantas holoepífitas cujos frutos são consumidos principalmente por um único gênero de aves, as Euphonia. Para verificar a hipótese de especialização na dispersão de sementes de Rhipsalis pelas Euphonia, inicialmente foi estudada a fenologia reprodutiva dessa epífita. Uma vez conhecido o período de disponibilidade de frutos maduros aos frugívoros, foram realizados registros eventuais de frugivoria e observações focais em indivíduos de Rhipsalis para definir a assembléia de frugívoros consumidores de seus frutos. Posteriormente, frutos de cinco espécies de Rhipsalis foram fornecidos a aves frugívoras mantidas em cativeiro. Testes de germinação foram realizados com as sementes que passaram pelo trato digestório dessas aves com o objetivo de verificar seu potencial como dispersoras efetivas das sementes de Rhipsalis. Os resultados obtidos demonstraram que o gênero Rhipsalis apresenta sincronia na produção das fenofases reprodutivas entre os indivíduos e atividade reprodutiva ao longo de todo o ano. A produção de frutos maduros teve duração longa entre os meses de junho e fevereiro. Todas as espécies apresentaram fenofases reprodutivas sazonais. As observações de frugivoria e os testes de germinação realizados confirmaram que as sementes de Rhipsalis podem ser dispersas por endozoocoria. O processamento dos frutos pelas aves frugívoras, especificamente a remoção da polpa que recobre as sementes, não apenas incrementou as taxas de germinação e germinabilidade das sementes, mas também se mostrou importante para...
Epiphytes are responsible for a great part of the plant diversity in Neotropical Forests. They are also important for animal diversity due to the production of food resources (e.g. flowers, fruits and leaves) and microhabitats used by a myriad of animal species. Rhipsalis (Cactaceae) is a holoepiphytic plant genus whose fruits are eaten mostly by a single bird genus, the Euphonia. To test the hypothesis that Rhipsalis presents a specialized seed dispersal system, firstly it was studied the reproductive phenology of this epiphyte. Once the availability of ripe fruits to birds was known, occasional frugivory records and focal observation on fruiting individuals of Rhipsalis were made to record the assemblage of animals that eat its fruits. Fruits of five species of Rhipsalis were offered to captive frugivorous birds to access their role as effective dispersers of Rhipsalis seeds. For this, germination tests were made with the seeds after they had passed through the birds’ digestive system. Results showed that Rhipsalis individuals have synchronized reproductive phenophases and the genus has reproductive activity along the year. Ripe fruit production lasted for a long period, between June and February. All species showed significant seasonality in the reproductive phenophases. Frugivory records and germination tests confirmed that the seeds of Rhipsalis may be dispersed by endozoochory. Additionally, the manipulation of the fruits by birds – specifically the removal of the pulp that recovers the seeds – provided higher germination rates and germinability to the seeds, suggesting that the passage though a bird’ gut is important to reactivate the metabolism of the seeds’ embryo. Although 31 animal species were recorded eating Rhipsalis fruits, Euphonia birds may be considered as the main consumer, being responsible for around 60% of feeding visits. Seed dispersal systems involving... (Complete abstract click electronic access below)
Epiphytes are responsible for a great part of the plant diversity in Neotropical Forests. They are also important for animal diversity due to the production of food resources (e.g. flowers, fruits and leaves) and microhabitats used by a myriad of animal species. Rhipsalis (Cactaceae) is a holoepiphytic plant genus whose fruits are eaten mostly by a single bird genus, the Euphonia. To test the hypothesis that Rhipsalis presents a specialized seed dispersal system, firstly it was studied the reproductive phenology of this epiphyte. Once the availability of ripe fruits to birds was known, occasional frugivory records and focal observation on fruiting individuals of Rhipsalis were made to record the assemblage of animals that eat its fruits. Fruits of five species of Rhipsalis were offered to captive frugivorous birds to access their role as effective dispersers of Rhipsalis seeds. For this, germination tests were made with the seeds after they had passed through the birds’ digestive system. Results showed that Rhipsalis individuals have synchronized reproductive phenophases and the genus has reproductive activity along the year. Ripe fruit production lasted for a long period, between June and February. All species showed significant seasonality in the reproductive phenophases. Frugivory records and germination tests confirmed that the seeds of Rhipsalis may be dispersed by endozoochory. Additionally, the manipulation of the fruits by birds – specifically the removal of the pulp that recovers the seeds – provided higher germination rates and germinability to the seeds, suggesting that the passage though a bird’ gut is important to reactivate the metabolism of the seeds’ embryo. Although 31 animal species were recorded eating Rhipsalis fruits, Euphonia birds may be considered as the main consumer, being responsible for around 60% of feeding visits. Seed dispersal systems involving... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Sementes, Sementes - Disseminação, Germinação, Sistema de dispersão especialista, Euphonia, Germinação de sementes, Specialized dispersal system, Seed germination
Como citar
GUARALDO, André de Camargo. Fenologia reprodutiva, distribuição espacial e frugivoria em Rhipsalis (Cactaceae). 2009. 83 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Rio Claro, 2009.