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Robin Snyder, PhD

Associate Professor of Biology

Research Interests


Environmental variability and its effects on species coexistence, distribution, and life history evolution

Environmental variation is ubiquitous and occurs at many spatial and temporal scales. It can be dramatic, as with drought or fire, or subtle -- ever notice that some plants fare better on the east side of your house and others on the west? Environmental variability can be both bane and boon. On the one hand, if conditions turn bad, stationary organisms like plants can't move somewhere better. They need strategies to reduce their risk, such as seed dormancy (which spreads seed germination out in time) or seed dispersal (which spreads seed germination out in space) or storage places for hoarding water and nutrients. On the other hand, environmental variability can enable some species to coexist that otherwise couldn't. Perhaps each likes slightly different conditions. Or perhaps they like the same conditions and the superior competitor is concentrated in the best spots, freeing up space for the inferior competitor elsewhere. I have spent several years thinking about how variation in time and space determines population distributions and the chances for two species to coexist.

Transient dynamics

A more recent interest of mine is transient (i.e. short-term) dynamics, especially transients that result from a change in the pattern of environmental variation (e.g. changes in grazing practices, fire suppression practices, rainfall patterns). Most ecological theory has focused on long-term dynamics: after everything has settled down, do populations reach some sort of equilibrium or stationary distribution? Well, yes, they generally do, but how long does this process of settling down take? (Hint: usually longer than the average grant cycle or monitoring program.) When dealing with longer-lived organisms, such as most plants, fish, birds, or mammals, what we observe in experiments is usually transient dynamics, not long-term dynamics. Furthermore, populations can undergo short-term changes that cannot be predicted from their long-term behavior, such as transient outbreaks or crashes. I'm working on understanding what makes populations take a long or short time to settle down, what makes them likely to undergo crashes or outbreaks, and what the consequences of transient dynamics might be for issues like invasibility.


I use mathematics to explore these questions. Simple mathematical models are useful in ecology because they can be far more general than an experiment. They can give us insights into what may be happening across different biological systems, they can test the logic of a verbal model ("I think X causes Y... but does that really hold water?"), and they can give us tips as to what would be the most useful experiments to perform next. Mathematical models are a wonderful tool for determining what can and cannot cause a phenomenon of interest. On the other hand, if you want to know for sure what's happening in a particular system, you have to do the experiment. I try to do most of my work with paper and pencil, since that yields the most general answers. However, computers are useful for testing how well my approximations hold, for visualizing my solutions, and for exploring systems that are too complicated to investigate just with paper-and-pencil math.

Key Words: Theoretical Ecology

Last Updated 12/02/2008