Andrew R. Tilman

Department of Biology
University of Pennsylvania

theoretical ecologist, social-ecological systems scientist, cross-country skier


About Me

I am a Postdoc in Erol Akcay and Josh Plotkin's labs at the University of Pennsylvania, studying eco-evolutionary feedbacks in game theoretic contexts. I completed my PhD in ecology, advised by Simon Levin, at Princeton University where my theoretical work focused on the management of common-pool resources. I use approaches from ecology, economics, game theory, and social-ecological systems to address questions of collective management. I also enjoy cycling, trail running, photography, and especially nordic skiing.




I am working with Avinash Dixit and Simon Levin to explore the relationships between prosociality and public goods provision. We are interested in how patterns of prosociality within and across groups shape the societal benefits produced through voluntary public-goods provision. We relate these findings to the nature of the public good in question, linking the ecology of the public good with the economic incentives of prosocial individuals. Further, we are also investigating different scaling relationships between group size and prosociality to better understand group structure that optimally supports public-goods provision. We see this as an important step toward better understanding the contexts (ecological, economic and social) where prosociality is most effective at averting tragedies of the commons.

Risk management

In collaboration with James Watson, I study the potential for novel risk management tools to be used as mechanisms for improved self-management in resource systems. Natural resource systems are susceptible to day-to-day and season-to-season variability, but in common-pool resource systems, such as fisheries, insurance against low harvests is rare. We are studying the potential for revenue-sharing cooperatives to provide insurance against harvest volatility in these systems while also creating incentives for sustainable harvesting. The goal is to better understand the conditions under which collective insurance schemes can be a tool for improved management.

Market structure

Colleagues from the Beijer Young Scholars group and I are developing a research agenda focused on the interactions among market concentration in a sector, policies governing resource use and resulting resource management or environmental quality. Many natural resource systems are exhibiting increased concentration among the firms in the market. How this consolidation interacts with management and policy-making remains an open question with implications for many of the sustainability challenges of our time. We are developing theoretical modeling frameworks to study these dynamical feedbacks with the goal of better understand how inequality among firms in a sector impacts stewardship.

Environmental feedbacks in evolutionary games

In many strategic settings, both in biological and social-ecological systems, strategies employed by individuals influence the environment over timescales that do not necessarily align with the outcome of the strategic interaction. I am working with Erol Akcay and Josh Plotkin to develop a general modeling framework for evolutionary games with environmental feedbacks that encompasses a broad class of problems in biology, psychology and human-environment systems. We seek to use this framework to make predictions about the circumstances in which the existence of environmental feedbacks fundamentally change predictions about system-level properties of the game-theoretic interactions.



In Review
  • Tilman, D & Tilman, A.R.. The food-web invasion and coexistence conundrum.