What I do
My work addresses fundamental questions in population, community, and evolutionary ecology. I am most interested in questions to do with system dynamics (changes over time) and the processes that drive them. Accordingly, much of my work uses a combination of mathematical modeling and experiments in tractable model systems such as laboratory microcosms. I use mathematical models because ecological and evolutionary systems are complex and nonlinear. It’s hard to develop and test rigorous hypotheses without mathematical help. I use microcosms because their high control and replicability allows powerful, rigorous experiments that would otherwise be impossible.
My lab is currently funded by an NSERC Discovery Grant.
Below are the main lines of research I’m currently looking for graduate students to work on. I have some other irons in the fire, but the lines of research listed below are the ones on which I plan to focus most of my research effort in future.
Spatially-separated populations of the same species often fluctuate synchronously, even though they’re hundreds or even thousands of km apart. The result is that, across vast areas, all populations increase (or decrease) simultaneously. Coexisting populations of different species also often fluctuate synchronously. Synchrony is pretty amazing when you think about it, and so cries out for an explanation. We have theories of why synchrony happens, but those theories are hard to test in nature because it’s impossible to do experiments at the right spatial and temporal scales. You can’t, say, manipulate the weather across all of Canada and then wait a century to see what happens to the spatial synchrony of lynx-hare cycles (and even if you could you wouldn’t have a control or any replication…). The solution is to scale nature down and do experiments in protist microcosms. I’m currently seeking grad students interested in pursuing synchrony-related experimental and modeling projects.
Much of my work on synchrony is in collaboration with my former postdoc David Vasseur of Yale University.
Publications: Vasseur & Fox 2007 Ecol. Lett., Vasseur & Fox 2009 Nature, Fox et al. 2011 Ecol. Lett., Fox et al. 2013 PLoS One, Vasseur et al. 2014 Proc Roy Soc B, Fox et al. 2017
Higher order interactions and species coexistence
Are ecological communities more than just the sum of their parts? If you knew enough about the population dynamics of each species on its own, and about all the pairwise interspecific interactions, could you predict the population dynamics of every species in the entire community? If not, the community dynamics are driven in part by “higher order” interactions: “emergent” effects that can’t be predicted just from knowledge of single-species and pairwise dynamics. Higher order interactions potentially present a major challenge to our ability to explain and predict community dynamics, but we don’t know much about their prevalence or importance. Ecologists have some good short-term case studies of some of the the biological mechanisms that can give rise to higher order interactions, but few long-term studies of their consequences for community dynamics. Protist microcosms are a great system in which to study the consequences of higher order interactions for community dynamics. Indeed, pioneering experiments tried to do this decades ago, but back then we didn’t have the statistical tools needed to properly analyze such experiments. We have those tools now. My current graduate student Ross Conner will be building on a pilot microcosm experiment by my undergraduate honors student Christine Song, quantifying higher order interactions and whether they typically promote species coexistence (as a bit of recent theory suggests they should). Ross will also be developing and testing hypotheses about the circumstances under which higher order interactions should be strong or weak.
Quantifying macroevolutionary forces using the Price equation
Fossil data record the macroevolutionary history of life on earth. Those data often record dramatic changes in major clades, such as the rapid dwarfing that N. American mammals underwent during the Paleocene/Ecocene Thermal Maximum (PETM) 55 MYa. Using an elegant theoretical tool called the Price equation, we can tease apart and quantify the causes of macroevolutionary change in any group of species at any site: species selection (non-random speciation and/or extinction with respect to species’ phenotypes), anagenesis (within-lineage evolution), and immigration of species to the site from elsewhere. In collaboration with my paleontologist colleague Jessica Theodor and her group, I’ve used this approach to discover that mammalian dwarfing during the PETM occurred despite species selection favoring larger mammals. My current student Kat Jordan is applying the same approach to other macroevolutionary datasets.
Publications: Rankin et al. 2015 Proc Roy Soc B.