Interests

I am Distinguished Professor of Mathematical Biology Emeritus in the Department of Applied Mathematics at the University of California Santa Cruz, Professor of Biology Emeritus in the Theoretical Ecology Group (Visit the TEG) at the University of Bergen, Norway and Affiliate Research Professor at the University of Washington, Tacoma. In my first job out of graduate school, I worked for the Operations Evaluation Group (OEG) of the Center for Naval Analyses doing operations research for the Navy. I moved to UC Davis in 1980 with the intention of doing OEG-style work, but with applications to fisheries and agriculture, and to UC Santa Cruz in 1996. I retired from formal teaching and administrative work in 2013 but continue an active research program. I am broadly interested in using mathematical methods to solve problems that arise in biology (especially ecology, evolution, and behavior) and work in what Donald Stokes called, in a wonderful book of the same name, Pasteur's Quadrant of use-inspired basic research, where a search for fundamental understanding is motivated by an important applied problem

Current Research Projects

Unifying Modeling Approaches for Better Understanding and Characterizing the Effects of Sound on Marine Mammals: Supported by the office of Naval Research, I am workng to find ways to unify Dynamic Energy Budget (DEB) models and Stochastic Dynamic Programming (SDP) models in order to better predict the consquences of acoustic disturbance on marine mammals. Population Biology and Cybersecurity : Since July 2018, I have been working with colleagues at the Johns Hopkins University Applied Physics Laboratory with the intention of using models from population biology to inform various aspects of cyber-security. Since June 2020, like many of my colleagues, I have also been helping colleagues at APL think about testing for covid-19, both at APL and in Howard County, MD (where APL is located) more generally.

The Role of Mesopelagic Fishes in Northeast Atlantic Marine Ecosystems . I am part of a project at the University of Bergen with Christian Jorgensen, Tom Langbehn, and Gabriella Ljungstrom on mesopelagic species in the Norwegian Sea. We have three objectives: i) to investigate the role of predation from mesopelagic fishes in driving latitudinal life history variation among copepods; ii) to identify the drivers of the unique migratory life history of Norwegian spring-spawning herring; and iii) to predict changes in the Norwegian Sea ecosystem as a response to climate warming. Mathematical Modelling of Biological Control Interaction to Support Agriculture and Conservation I am part of a research group) organized by Tamar Keasar, Michal Segoli, and Eric Wajnberg and supported by the Israel Institute of Advanced Studies. Our study group spans the continuum between theoretical approaches (behavioral, population and community ecology) and application (biological control). We will meet formally in Jerusalem in the first half of 2022, but we are already working together remotely. Our main aim is to bridge the existing gaps between the well-developed theory of interactions between insects and their natural enemies, and the optimization of the efficacy of biological control projects in agriculture and conservation. I am particularly thrilled to be involved with this group of scientists that includes two of my students (George Heimpel and Asaf Sadeh), one of my post-docs (Tamar Keasar), and my long-time collaborator Bernie Roitberg.

Recently Completed Projects

Population Consequences of Disturbance : Starting in 2016, I worked with Liz McHuron, Leslie New, Enrico Pirotta, and Lisa Schwartz to develop state dependent life history models of how anthropgenic disturbance of foraging habitats will affect marine mammals. We have thus far developed a general framework, and applied it to California sea lions, blue whales, and the western population of gray whales. Informing population models with evolutionary theory to infer species' conservation status (NSF-NERC grant (2016-2019) with Holly Kindsvater (Rutgers), Jason Matthiopoulos (Glasgow), and Nick Dulvy (Simon Fraser)). We used a combination of evolutionary theory and Bayesian population modeling to make inferences about the status of data-poor stocks. I used state dependent life history theory to produce scientifically based priors for use in the population dynamics by solving the inverse problem -- observing life history traits and inferring the environment from them. Another overall goal of the project was to unify size spectra theory and Stochastic Dynamic Programming models for life histories.

My Approach to Mathematical Biology

I use models (differential equations, stochastic dynamic programming and Bayesian statistical methods), experiments (either here in Santa Cruz or in collaboration with colleagues elsewhere) and field observations. I have applied these ideas to a variety of systems, including insect parasitoids, tephritid fruit flies, marine mammals, southern ocean krill, steelhead trout, Pacific rockfish, and planaria.