Dimensions: Coexistence, Herbivore Host Choice, and Plant-Herbivore Evolution in the Recently Radiated and Speciose Neotropical Tree Genus, Inga

University Of Utah, Salt Lake City UT

Investigators

Abstract

Tropical forests are extremely diverse and the origin of such high diversity is a central question in biology. This project will explore how the interactions between plants and the insects that consume plants (herbivores) may contribute to this high diversity. Plants have evolved a battery of defenses to protect their leaves from insects, and insects are continually evolving counter-adaptations. Although it is hypothesized that the rate of defense evolution is extremely fast, how this evolutionary process proceeds is still poorly understood. The research addresses how herbivores drive the evolution of plant defenses, how plant defenses influence which species of plants herbivores consume and how plant-herbivore interactions might influence plant community composition and diversity in the tropics, the most species-rich forests in the world. It will focus on the taxonomic, genetic and functional diversity of trees in the genus Inga (Leguminosae) and its insect herbivores at five sites in Central and South America. Inga is one of the most speciose (more than 300 species) and among the most locally diverse and abundant Neotropical trees. This interdisciplinary study will measure plant defenses, including chemical toxins, physical defenses and the attraction of protective ants to sugar-bearing nectaries on the leaves. DNA sequencing of herbivores and Inga will allow quantification of the diversity of species, will test whether more closely related Inga species have more similar defenses, and will determine whether herbivores choose hosts based on the similarity of their defenses. It is hypothesized that if plant species differ in their defenses, they will be attacked by different herbivore species, and thus can coexist as neighbors, leading to high local diversity typical of tropical forests. Thus this project will shed light on the origin and maintenance of biological diversity. Ongoing loss of biodiversity is a critical issue for science and society. The research will be communicated to different audiences in order to enhance their appreciation of nature and science. The team will create a theater of biodiversity for school children and families in Utah, conduct Tom Sawyer style Saturday science days for children from poor communities near the Brazil and Peru field stations, give presentations on tropical diversity for tourists, and develop the use of Inga in agroforestry in Peru. The integrative project will also create an open, accessible website to share data and other project results, and to facilitate related research by other scientists.