| Author(s): |
Mário Almeida Neto
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. , ilustrações. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2006-11-27 |
| Examining board members: |
Thomas Michael Lewinsohn;
André Victor Lucci Freitas;
Carlos Roberto Sorensen Dutra da Fonseca;
Glauco Machado;
Sergio Hayato Seike
|
| Advisor: | Thomas Michael Lewinsohn |
| Field of knowledge: | Biological Sciences - Ecology |
| Indexed in: | Base Acervus-UNICAMP; Biblioteca Digital da UNICAMP |
| Location: | T/UNICAMP; AL64e; Universidade Estadual de Campinas. Biblioteca Central Cesar Lattes; T/UNICAMP; AL64e |
| Abstract | |
This study aimed to investigate the effects of anthropogenic disturbance on the diversity and structure of interactions between species of Asteraceae and the endophagous insects whose larvae feed inside their flower heads. Field sampling was performed in 20 remnants of cerrado vegetation in three adjacent counties in the state of São Paulo, Southeastem Brazil. The density of invasive grass cover was used as surrogate of anthropogenic disturbance leveI. Asteraceae richness showed a quadratic ;elationship with disturbance and peaked at intermediate disturbance levels. The proportion of typical Asteraceae from cerrado decreased in more disturbed sites, but the taxonomic distinctness of Asteraceae did not change consistently along the disturbance gradient. As expect, host plant richness was the major predictor ofherbivore richness. Consequently, the richness of endophages also showed a quadratic variation along the disturbance gradient. However, when the effect of host plant richness on endophages is added into a multiple linear regression, the final direct effect of disturbance on insect richness is negative. Thus, the quadratic relationship between disturbance and endophage richness is explained through an indirect effect via host plant richness. The number of interactions between endophages and plants was also quadratical1y related to disturbance. Since connectance as a rule is negatively related to species number, those sites with intermediate disturbance levels presented lower connectance values than sites at the extremes of the gradient. Afier controlling for the influence of species richness on connectance values, this network property decreased at higher disturbance levels. The degree of nestedness of recorded plant-herbivore interactions was ais o lower in more disturbed sites. In contrast, disturbance leveI had no consistent effect on the leveI of compartmentation of the interactions. Finally, anthropogenic disturbance affected the fragility ofthe plant-herbivore intera~tion networks to secondary extinctions, but their effects were not uniform along the disturbance gradient (AU) | |
| FAPESP's process: | 03/02548-1 - Effect of the degradation of habitat on community patterns and properties of trophic networks between plants and phytophage insects |
| Grantee: | Mário Almeida Neto |
| Support Opportunities: | Scholarships in Brazil - Doctorate |