Polinização e qualidade de sementes produzidas por Pychotria tenuinervis (Rubiaceae) em fragmentos de Mata Atlantica : efeito da distancia de bordas antropicas e naturais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Spatial and temporal climatic variability among areas may affect the reproductive events of plant and animal populations. Habitat changes or abrupt limits between habitats can affect the interactions between plants and their pollen and seed vectors and lead to a decrease in seed quality because of increased inbreeding. The isolation of forest patches and the edges created by fragmentation may change the abiotic and biotic conditions among and within forest fragments; they also could affect some aspects related to plant reproduction and gene flow, decreasing seed quality due to the inbreeding. These changes could also occur at natural edges (limits between forests and rivers or streams). Plants near anthropogenic and natural edges could present alterations of their gene flow and consequent1y in the quality of their seeds. The aim of this thesis was to investigate whether, on a regional scale, there were (i) c1imatic differences among forest fragments, (ii) influences of climatic conditions on the reproductive phenology of P. tenuinervis, or differences in (iii) reproductive phenology of P. tenuinervis arnong forest fragments, and on a local scale, whether there were differences (iv) in microc1imate, (v) reproductive phenology, (vi) community of flower visitors, (vii) genetic variability and structure, and (viii) mass, rate and velocity of germination of seeds produced by Psychotria tenuinervis located on anthropogenic edges (AE), natural edges (NE) and in the forest interior (FI). The study was carried out, on a regional scale, in tive fragments in Rio de Janeiro, Brazi1, and on a local scale, within one of them. In spite of differences in climatic conditions among the five fragments, the phenological pattem of P. tenuinervis found in the two years was similar among them. These results indicated that the general pattern of reproductive phenology of this plant species, on a regional scale, could be influenced by evolutionary factors. On a local scale, there were no differences, among the three habitats, in microclimate, phenological pattern, rate of flower visits (only in 2002, NE with more and . AE fewer visits), fruit and seed production, genetic variability and structure, and rate and velocity of seed germination. These pattern may occurr due to the great variation among the sample plots within each habitat. The heterogeneity found within each habitat, and the probable greater importance of gaps or edge age instead of the distance from the edges, could be very important for conservation programs of forest habitats

ASSUNTO(S)

isoenzimas polinização genetica

ACESSO AO ARTIGO

Documentos Relacionados