Distribution and diversity of leaf litter ants (Hymenoptera: Formicidae) along an elevational gradient in the Parque Estadual da Serra do Mar - Núcleo Picinguaba, São Paulo, Brazil / Distribuição e diversidade de formigas de serapilheira (Hymenoptera: Formicidae) ao longo de um gradiente elevacional no Parque Estadual da Serra do Mar-Núcleo Picinguaba, São Paulo, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Aiming to investigate the influence of the elevation in topography on the myrmecological leaf litter fauna and to verify if there is a richness pattern for the investigated gradient, I studied the distribution of these ants along an elevational gradient in the Núcleo Picinguaba of the Serra do Mar State Park, Ubatuba, SP. For this, I adopted six elevational bands (50, 200, 400, 600, 800 and 1000 meters) at the Eastern coast of the Corisco and Cuzcuzeiro mountains, where I collected 20 1 m2 leaf litter samples at each band along two transect of 225 m each and measured the leaf litter depth of each sample. The 120 samples were submitted to mini-Winkler extractors to remove of the ants. The observed richness in the whole gradient was 176 species and the estimated richness (N = 206; sd = 5,17) was calculated with the best index according the literature, relating observed richness to the elevational variation and to the leaf litter depth using regressive models. The observed richness pattern revealed a peak at the mid-elevational band of the gradient (400 meters quota) with 103 species; the mid-domain effect theory being tested to explain the species distribution. The results indicate that the distribution is influenced by stochastic processes and/or biotic or abiotic factors. To verify if there is variation on the ant fauna along the gradient, I applied the appropriate dissimilarity index for the data types, correlating the obtained results with the elevational variation using the Mantel test. Moreover, I used a detrended correspondence analysis (DCA) to understand how the myrmecological community in question is structured. The dissimilarity analysis and the Mantel test showed that the fauna changed significantly along the gradient. However, the DCA indicated a gradual substitution along the elevational gradient with two distinct assemblages, one in the lower zone and other in the upper zone, with a continuum between them. Furthermore, I verified the presence of exclusive species at each elevational band to understand the dynamics of the community, using a regressive model. The richness of these exclusive species was greatest at the extremities of the gradient, mainly at the 1000 meters quota, where the area is smaller; and it was smallest at the mid-elevations (200 and 400 meters), where the richness estimatives were greater. Considering the obtained results, I suggest that the biotic factors have a preponderant role in the species distribution and in the definition of the richness pattern. However, the influence of these factors may be only evaluated with the study of the ant guilds structure along the elevational gradient.

ASSUNTO(S)

diversity formigas gradiente elevacional ants floresta atlântica atlantic forest elevational gradient

ACESSO AO ARTIGO

Documentos Relacionados