EAGER: Effects of Leaf Diversity on Aquatic Insect Colonizer Diversity

The diversity of animals often increases with the diversity of plants in a community. One reason for this might be that animals choose habitats with more diverse plants. These diverse plants may provide a higher variety of nutrients or other resources to support a more diverse animal community. Diversity can be measured by the variety of species, variety of the roles that species play, or the variety of evolutionary histories of those species. This project examines the importance of these different types of diversity by manipulating the mixtures of dead tree leaves in artificial ponds and estimating the diversity of insects choosing those ponds. To examine the diversity of aquatic insects, the research will also consider the variety of species, species roles (particularly diet), and evolutionary histories. This research will provide important information on how the diversity of trees surrounding aquatic habitats affects aquatic biodiversity, providing guidance on forestry management relating to the conservation and restoration of aquatic communities. This project will also involve mentoring undergraduate and high school students from underrepresented backgrounds to perform scientific research, as well as provide outreach on the diversity of trees and aquatic insects to the general public. The project will simultaneously manipulate species, functional, and phylogenetic diversity of leaf litter in pond mesocosms and examine effects on species, functional, and phylogenetic diversity of aquatic insect colonizers. The research will also examine the form of the relationship to determine if an increase in resource diversity affects colonizer diversity with a form that is linear, log-linear, or quadratic with an intermediate peak. This information will be important to guide future work on potential mechanisms of why aquatic insect diversity is related to particular types of leaf litter diversity. The experimental design will use a species pool larger than the highest species richness treatment to avoid confounding species richness and community composition, and checks will be performed to prevent confounding leaf litter species, functional, phylogenetic diversity, and average leaf traits. Researchers will measure continuous functional traits of aquatic insects by measuring their size and using stable isotopes to estimate trophic position and trophic niche breadth, which will provide better resolution at the species level than previously used categorical traits. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.