Peter Chesson's research questions primarily concern how the adaptations of organisms to variable environments promote species diversity and affect ecosystem functioning. He investigates these questions using mathematical models and experiments in natural systems. Recent research topics have involved neighborhood competition, community assembly, invasion resistance, life-history evolution, temporal and spatial niches in their various forms, and multitrophic diversity maintenance. In addition, he is involved with field projects on annual plants in Arizona, Australia and California, and has studied herbaceous perennial plants in Australia. Major thrusts at the present time are the development of the methodology for field testing hypotheses on diversity maintenance, putting foodwebs into diversity maintenance theory, and testing and developing invasion theory.