Biologia reprodutiva de três espécies distílicas de Psychotria L. e efeitos da fragmentação florestal no sucesso reprodutivo e na diversidade genética de P. hastisepala Müll. Arg. (Rubiaceae) / Reproductive biology of three distylous species of Psychotria and effects of forest fragmentation in the reproductive success and the genetic structure on P. hastisepala Müll. Arg. (Rubiaceae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The aims were to analyze the aspects of reproductive biology, including the reproductive success, of three Psychotria distylous species, P. conjugens, P. hastisepala and P. sessilis, in 2004/2005 and 2005/2006, in the largest forest fragment in the municipality of Viçosa (2045S and 42 54W), in the state of Minas Gerais, southeastern Brazil. Besides that, it was to verify how the forest fragmentation has been affecting the reproductive success and the genetics structure of P. hastisepala, using ISSR markers, in seven forest fragments, with different dimensions. The flowering of the species was in sequence, in the rainy season, initiated by P. sessilis, followed by P. conjugens and, last, P. hastisepala. There was a flowering synchronism among the floral morphs. The species were pollinated by bees in common, including Melipona species, and, mainly, Ariphanarthra palpalis. The same bees, including Melipona species and, mainly Ariphanarthra palpalis, pollinated the three species and also visited the morphs of each species. There was a tendency of one of the morphs to be visited more than the other, especially the long-styled flowers. There were yearly variations in the composition and abundance of the pollinator species. The attractiveness to the flowers seemed to be dependent on the number of inflorescence produced and the open/individual /day flowers. The fructification of the three species was synchronized. In an area of seven hectares, the species population are in isoplethic and the in vivo manual pollinations show intra morphs incompatibility. The pollen viability was high (>64%), in both morphs of the three species. The diameter of the pollen grains of the short-styled flowers was significantly higher, in all the species. The natural fructification was high (≥53%) in both morphs of P. sessilis and in the short-styled flowers of P. hastisepala. In P. conjugens and in the long-styled flowers of P. hastisepala the natural fructification was low (≤ 29%). There wasnt any significant difference in the number of fruit and seeds between the morphs in P. sessilis and P. conjugens. The short-styled flowers of P. hastisepala produced a number of fruit and seeds significantly higher than the long-styled flowers. P. conjugens showed one of the lowest total quantity of seed and its low reproductive success seems to be related to the pollen limitation. In P. hastisepala, the occlusion of the stigma, with incompatible pollen , and the damages caused by herbivores to the stigma can be factors related to the low reproductive success of the long-styled flowers. In the analysis of the genetic structure of P. hastisepala, the Shannon (I) and Nei (HE) indices and the AMOVA revealed high genetic variation within and among forest fragments. It wasnt obtained significant correlations between the geographic distance and genetic distance. In all the fragments, the reproductive success was higher in the short-styled flowers, not showing a clear correlation to the size of the fragment. The results showed that the reproductive success can be influenced by the quality of the matrix, availability of the pollinators, size of the sampling, and maintenance of the occurrence habitat of the species.

ASSUNTO(S)

psychotria reproductive success polinizadores diversidade genética fragmentação florestal psychotria flowering phenology genetic diversity sucesso reprodutivo molecular marker issr fenologia de floração marcador molecular issr botanica forest fragmention pollinators distilia distylous

ACESSO AO ARTIGO

Documentos Relacionados