Research

Understanding the emergence and persistence of cooperation is a fundamental problem in evolutionary biology. Cooperation is needed for the evolution of higher levels of organization. Genomes, cells, multicellular organisms, and human society are all based on cooperation. Since evolution is based on competition between individuals, it should reward only selfish behavior as cooperators forgo some of their reproductive potential to help others. Yet cooperation abounds in nature and human society, and one of the most remarkable aspects of evolution is its ability to generate and maintain cooperation in a competitive world. I investigate effects of spatial structure and mobility on the evolution of cooperation. I also model interactions in realistic populations via multiplayer games on networks.

Voluntary vaccination policies present a subtle challenge: if a sufficient proportion of the population is already immune, either naturally or by vaccination, then even the slightest risk associated with vaccination will outweigh the risk from infection. As a result, individual self-interest might preclude complete eradication of a vaccine-preventable disease. I construct and solve game-theoretic models involving individual’s decision regarding the level of personal protection for known infectious diseases. Personal protection could take on many different forms, including vaccination, using repellent to protect oneself from insect bites, drinking clean water to avoid infection, etc.

The distribution of animals around their environment is one of the cornerstones of ecology. The ideal free distribution (IFD) describes the distribution of animals which are “ideal”, meaning they are assumed to always go to the patch where their intake is highest, and “free” in that they can enter any patch without restriction or cost in terms of time or energy. However, experiments show that there is a bias for overusing poor patches and underusing good patches in many animals. Considerable effort has been devoted to studying potential causes for departures from IFD. I investigate the effects of perceptual constraints on IFD, and spatial distributions of generalists vs. specialists.