Ant community in natural fragments of the Brazilian wetland: species–area relation and isolation

Abstract

Biogeographic theory has been given much attention for its potential application to biodiversity conservation in areas fragmented through anthropic action. The objective of this study was to determine whether ant community structure established in natural woodland fragments immersed in a matrix of natural grasslands could be explained by this theory. We therefore investigated whether the relationship between species richness and both area and isolation that have previously been found in anthropogenically formed forest fragments are applicable to naturally formed forest fragments. The sampling consisted of eight natural woodland fragments with varying areas and degrees of isolation. Sampling was undertaken proportionally to the fragment size, and each sampling point was spaced at least 10 m apart. Ants were collected from each point through arboreal and epigeic “pitfall” traps. In addition, five epigeic traps were placed 100 m from each sampled fragment in the adjacent grassland. A total of 81 ant species were sampled. Total and epigaeic species richness increased with size of area and fragment isolation. However, arboreal ants responded positively only with respect to increasing area, but not with isolation. Moreover, specialist and generalist species richness had a positive relationship with area, but not with isolation. Biogeographic Theory can only be applied to some of the patterns found in the natural fragments in the present study. This positive relationship of ant richness and isolation suggests that these environments bear unique characteristics and therefore, must be regarded as conservation targets. The results obtained in this study suggest the need for further studies, to reinforce the importance of biodiversity conservation of this characteristic habitat in the Pantanal.