Polinização e dispersão de sementes em solanaceas neotropicais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

To understand the ecological processes that provides the functioning of an ecosystem implies in conducting multiple studies about its components and interactions. In this sense, it is very important to know the functional relationships of the species and to make comparisons (both intercommunity and pancommunity) among groups of species phylogenetically related. In this work, it was studied the ecology of Solanaceae seed dispersal under four main aspects: a) the characteristics of the fruits and their type of dispersal; b) the phenology of Solanum inodorum and its interaction with flower visitors and frugivores; c) the dispersal ecology of S. thomasiifolium, with main importance on the foraging strategy of frugivores and sites of seed deposition; d) the pollination and seed dispersal syndromes in equivalent neotropical mountain cloud forests in Mexico and in Brazil. Solanaceae are valuable in the medical and pharmacological areas and as food resource, besides being important as colonizers of open and disturbed areas. Seeds of Solanaceae are dispersed (chapter 1) by anemochory, autochory, barochory, chiropterochory, epizoochory, hydrochory, mammaliochory (non flying mammals), ornitochory and saurochory. Among the 102 species of the Brazilian flora which were analised (28% of the total number of Solanaceae species in Brazil), chiropterochory (38,23%) and barochory predominated. In other countries, like Australia and Mexico, ornitochory predominated. For a better understanding of the processes involved in seed dispersal, it was conducted two studies, presented here in the second and third chapters. It was observed seasonal patterns of flowering and fruiting of S. inodorum. Flowering is, asynchronic coinciding with the dry season (July) and with availability of mature fruits in the beginning of the rainy season (November). Flower visitors are composed by ten bee species. Those which were potentially more efficient (that visited a higher number of flowers/short visit) were Xylocopa (Neoxylocopa) ordinaria, Exomalopsis (phanomalopsis) aureosericea. The frugivores were Elaenia jlavogaster, Virio olivaceus, Saltador similis and Penelope superciliares (species that consumed more fruits). Seeds that were taken off the fruits germinated at the rate of 26%, seeds that were treated with NaCl -4% and those obtained in feces reached 13%. lnteractions of S. thomasiifolium with frugivores and its ability to germinate was studied (chapter 3). Fruiting took place in July, 1996 and frugivores were a mammal (Cerdocyon thous) and a lizard (Tropidurus torquatus). The estimated percentage contribution of each dispersor was 77%, 19% and 4% respectively. The germination rates of control seeds and those obtained in feces of bird, mammal and lizard were, 64%, 64%, 53% and 80% respectively. The differences were statistically significant, except between seeds obtained from feces of birds and control. From the understanding of the processes involved in dispersal ecology, we asked if there were similar functional spaces in equivalent communities. So in the forth chapter, pollination syndromes in equivalent mountain c1oud forests in Mexico and in Brazil were analised, and it was found that melittophily is the main syndrome in both countries; among seed dispersal syndromes it was observed a significant difference, in Mexico ornitochory was the most frequent whereas in Brazil chiropterochory was the most abundant. Finally, this work shows that the study of ecological interactions is important in the reproductive process of Solanaceae, being through pollinators and/or its dispersors. So dispersors play a fundamental role in the colonization of new areas and are important in the population dynamics of Solanaceae. Therefore, conservation and management of Solanaceae depend on holistic studies that integrate ecological processes involved in pollination and seed dispersal

ASSUNTO(S)

polinização dispersão solanacea interação animal-planta

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