Comments on plant-herbivore-parasitoid interactions in two cerrado areas of Southern Brazil

This work describes some interactions between lepidopteran larvae and braconid parasitoids on a group of plants at two sites. There was no significant difference in parasitoid diversity between the sites (Shannon index, p<0.05), and similarity was 62.5%, estimated through Sorensen's index. The diversity of hosts was also not different (p<0.05), but the similarity of host diversity was only 28.5%. This suggests that the parasitoids have strategies for maintaining similar reproduction rates, population densities and communities in areas with different potential hosts

Ecological and evolutionary significance of dispersal by freshwater invertebrates

Traditional expectations for how widely and how often freshwater invertebrates disperse differ from empirical data. Freshwater invertebrates have been characterized as frequent, widespread dispersers, particularly those that are transported passively. Our review finds that this characterization may describe the potential for dispersal in some taxa, but it is not an accurate generalization for actual dispersal rates. High variance among habitats and taxonomic groups is a consistent theme. Advances in population genetics may help resolve these issues, but underlying assumptions should be carefully tested. Further, even unbiased estimates of gene flow may not equate with individual movement, because not all dispersers survive and reproduce. Some freshwater invertebrates may exist in classic Levins metapopulations. However, other species fit into a broader metapopulation definition, where temporal dispersal via diapause is functionally equivalent to spatial dispersal. In the latter case, local extinctions and rescue effects may be rare or absent. Finally, limited dispersal rates in many taxa suggest that theories of freshwater community assembly and structure can be made more robust by integrating dispersal and local processes as joint, contingent regulators. Recent research on freshwater invertebrate dispersal has substantially advanced our basic and applied understanding of freshwaters, as well as evolutionary ecology in general