Does taxonomic and numerical resolution affect the assessment of invertebrate community structure in New World freshwater wetlands?

The efficiency of biodiversity assessments and biomonitoring studies is commonly challenged by limitations in taxonomic identification and quantification approaches. In this study, we assessed the effects of different taxonomic and numerical resolutions on a range of community structure metrics in invertebrate compositional data sets from six regions distributed across North and South America. We specifically assessed the degree of similarity in the metrics (richness, equitability, beta diversity, heterogeneity in community composition and congruence) for data sets identified to a coarse resolution (usually family level) and the finest taxonomic resolution practical (usually genus level, sometimes species or morphospecies) and by presence-absence and relative abundance numerical resolutions.

Climate-driven habitat size determines the latitudinal diversity gradient in temporary ponds.

The latitudinal diversity gradient (LDG) has been one of the most documented patterns in ecology, typically showing decreasing species diversity with increasing latitude. Studies of these patterns also used different spatial scales and dispersal traits to better understand the underpinning ecological factors. Seasonal freshwater ecosystems are less studied and may exhibit different patterns because they are more sensitive to climatic variation, which result in an inundation-desiccation cycle.

A parasitic plant increases native and exotic plant species richness in vernal pools.

Species interactions are well known to affect species diversity in communities, but the effects of parasites have been less studied. Previous studies on parasitic plants have found both positive and negative effects on plant community diversity. Cuscuta howelliana is an abundant endemic parasitic plant that inhabits California vernal pools.

Are trade-offs among species' ecological interactions scale dependent? A test using pitcher-plant inquiline species.

Trade-offs among species' ecological interactions is a pervasive explanation for species coexistence. The traits associated with trade-offs are typically measured to mechanistically explain species coexistence at a single spatial scale. However, species potentially interact at multiple scales and this may be reflected in the traits among coexisting species.

Environmental correlates of abundances of mosquito species and stages in discarded vehicle tires.

Discarded vehicle tires are a common habitat for container mosquito larvae, although the environmental factors that may control their presence or abundance within a tire are largely unknown. We sampled discarded vehicle tires in six sites located within four counties of central Illinois during the spring and summer of 2006 to determine associations between a suite of environmental factors and community composition of container mosquitoes. Our goal was to find patterns of association between environmental factors and abundances of early and late instars.

Ecosystem-phase interactions: aquatic eutrophication decreases terrestrial plant diversity in California vernal pools.

Eutrophication has long been known to negatively affect aquatic and terrestrial ecosystems worldwide. In freshwater ecosystems, excessive nutrient input results in a shift from vascular plant dominance to algal dominance, while the nutrient-species richness relationship is found to be unimodal. Eutrophication studies are usually conducted in continuously aquatic or terrestrial habitats, but it is unclear how these patterns may be altered by temporal heterogeneity driven by precipitation and temperature variation.

Richness-productivity relationships between trophic levels in a detritus-based system: significance of abundance and trophic linkage.

Most theoretical and empirical studies of productivity-species richness relationships fail to consider linkages among trophic levels. We quantified productivity-richness relationships in detritus-based, water-filled tree-hole communities for two trophic levels: invertebrate consumers and the protozoans on which they feed. By analogy to theory for biomass partitioning among trophic levels, we predicted that consumer control would result in richness of protozoans in the lower trophic level being unaffected by increases in productivity, whereas richness of invertebrate consumers would increase with productivity.

Intermediate-consumer identity and resources alter a food web with omnivory.

1. Omnivory is an important interaction that has been the centre of numerous theoretical and empirical studies in recent years. Most of these studies examine the conditions necessary for coexistence between an omnivore and an intermediate consumer.

A critical review of twenty years' use of the resource-ratio theory.

A model of species interactions based on their use of shared resources was proposed in 1972 by Robert MacArthur and later expanded in an article (1980) and a book (1982) by David Tilman. This "resource-ratio theory" has been used to make a number of testable predictions about competition and community patterns. We reviewed 1,333 papers that cite Tilman's two publications to determine whether predictions of the resource-ratio theory have been adequately tested and to summarize their general conclusions.