Coevolution, convergence, and the origins of biodiversity

External Cooperation: Prof. Dr. Anurag Agrawal, Cornell University, USA Prof. Dr. Noah Whiteman, University of Arizona, USA

A proposal submitted to the John Templeton Foundation from

Cornell University, Universität Hamburg, & University of Arizona

Principle Investigators: Profs. Anurag Agrawal, Susanne Dobler, Noah Whiteman

The evolution of plant-feeding insects is one of the most dramatic and rapid radiations of life on our planet. With some 500,000 described species (a quarter of all described macroscopic organisms) and an estimated 2-5 million species in total, understanding the mechanisms that have led to this radiation has been a central problem in ecology, evolution, and biodiversity studies. Central to understanding insect diversification under the above hypothesis is the hierarchical concept of convergent evolution. The repeated and independent colonization of, adaptation to, and subsequent speciation on, the same host plant niches is necessary if plant driven diversification produced the extreme radiation of herbivorous insects we see today. But is “convergence on host use” a sufficient explanation, or do we need to dig deeper into behavioral, physiological, and genetic mechanisms? Perhaps convergence at the molecular sequence level is rare and less necessary for diversification than convergence at such higher levels of organization. And does such convergence always take the same form, maximizing the highest benefit-to-cost ratio of the possible convergent solutions, or are there other forms of constraint? These questions have been of long-standing importance in biology and understanding the history of life, but relatively few answers, especially answers that can be generalized across taxa, have emerged.
This proposal seeks to answer the above questions using the interdisciplinary approaches of physiology, phylogenetics, chemical biology, genetic transformation, and ecology. Through the integration of these methods, we aim to unravel the causes and consequences of convergent shifts to toxic host plants across five very disparate clades of insects. We have assembled a team of researchers from three major internationally recognized universities, with a plan for addressing a fundamental question in evolutionary biology using an integrative approach and model systems.