Effect of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora, a tree native to the Atlantic Forest.
Habitat  fragmentation, caused by the expansion of agriculture in natural areas, may be  one of the strongest impacts humans have on the ecosystem. These changes can  decrease the number of individuals in a population, leading to endogamy. In  allogamous species, endogamy can have a negative effect on reproductive  capacity. In this study, we analyzed the effects of forest fragmentation on microsporogenesis  and pollen viability in Eugenia uniflora L., a tree species native to  the Atlantic Forest. We analyzed 4 populations, 3 of which were connected by  forest corridors and 1 of which was isolated by agricultural fields on all  sides. For microsporogenesis analysis, 9000 meiocytes representing all stages  of meiosis were evaluated. To perform the pollen viability test, we evaluated  152,000 pollen grains. Microsporogenesis was stable in plants from populations  that were connected by forest corridors (abnormalities, less than 6%), while  microsporogenesis in plants from the isolated population showed a higher level  of abnormalities (13-29%). Average pollen viability was found to be more than  93% in the non-isolated populations and 82.62% in the isolated population. The χ(2) test showed  that, in the isolated population, the meiotic index was significantly lower  than that in the non-isolated populations (P = 0.03). The analysis of variance  for the percentage of viable pollen grains confirmed the significant difference  between the isolated and non-isolated populations. Our data show that forest  fragmentation has a direct effect on microsporogenesis and pollen viability in E.  uniflora and can directly influence the reproductive capacity of isolated  populations of this species.
Programa de Pós-Graduação em Biologia Evolutiva, Universidade Estadual do Centro-Oeste, Guarapuava, PR, Brasil.
D J
DJ
de Almeida
M V
MV
Faria
P R
PR
da Silva
D000383:Agriculture; D001938:Brazil; D003247:Conservation of Natural Resources; D017753:Ecosystem; D016468:Forestry; D056130:Gametogenesis, Plant; D008540:Meiosis; D051479:Plant Infertility; D011058:Pollen / Q000166:cytology / Q000502:physiology*; D027842:Syzygium / Q000166:cytology / Q000502:physiology*