Postdoctoral Fellow, Wolkovich Group
Forest and Conservation Science
University of British Columbia
geoffrey.legault@ubc.ca

Hello! I am interested in a variety of topics in the fields of ecology and evolutionary biology, including: range expansion, phenology, coexistence, synchrony, and life history. To answer questions in these areas, I use or derive mathematical models to make predictions about what is possible. I also try to link the possible with the actual by fitting models to data.

I am particularly interested in applications of stochastic models, as they can account for unknown or unmeasured sources of variation, both of which are common in biological systems.

You can read more about my research by scrolling down or clicking here.

News

Curriculum vitae

Google scholar profile | ORCID profile

You can download my CV here (updated 2020-02-25)

Research

Range expansion and competition

As early as Darwin, ecologists recognized that species ranges were constrained by both abiotic and biotic factors. However, models of species' range dynamics routinely incorporate only abiotic factors (e.g., species distribution models).

With Brett Melbourne and Alan Hastings, I combine stochastic spatiotemporal models with experimental microcosms of flour beetles (Tribolium castaneum and Tribolium confusum) to examine how competition affects range expansion.

spreadexample.png

Figure 1: Illustrative example of beetles (black dots) spreading across a one-dimensional landscape over 2 generations.

Life history traits and trade-offs

Life history traits (e.g., maturation time, mass at maturity) frequently co-vary and exhibit important trade-offs. Characterizing such trade-offs is necessary for predicting lifetime fitness and optimal evolutionary strategies. I develop stochastic models of life history traits and validate them with real data, in order to better understand how these trade-offs manifest in natural systems.

During my postdoc with Joel Kingsolver, I created a continuous-time stochastic model describing the joint distribution of an insect's age and mass at maturity. The mechanistic model is based on the feeding behavior and developmental biology of Manduca sexta, and predicts novel trade-offs between age and mass at maturity. I am currently working to validate this model with data from laboratory experiments.

      devmass_model.png devmass_sensitivity.png      

Non-stationary demography and phenology

Species' responses are strongly affected by abiotic factors such as temperature and precipitation. Due to seasonality and climate change, these factors change through time. As a consequence, phenological and demographic responses are necessarily non-stationary (i.e., their distributions changes through time). Accounting for non-stationarity is challenging, particularly for stochastic models. This limits the utility of stochastic modeling for natural systems that regularly experience non-stationary environments.

During my Ph.D., I developed a method for simulating non-stationary demography in continuous-time. You can read the paper about it here.

Currently, I use winegrapes as a model system for creating stochastic non-stationary phenological models.

      winegrape.jpg vines_heatwave.jpg      

Publications

Google scholar profile | ORCID profile

2020

  1. Legault, G., Kingsolver, J. (2020) A stochastic model for predicting age and mass at maturity of insects. The American Naturalist. Accepted. data
  1. Bullock, M., Legault, G., Melbourne, B. A. (2020) Interspecific chemical competition between Tribolium castaneum and Tribolium confusum reduces fecundity and hastens development time. Annals of the Entomological Society of America link

2019

  1. Legault, G., Fox, J., Melbourne, B. A. (2019) Demographic stochasticity alters expected outcomes in experimental and simulated non‚Äźneutral communities. Oikos 128(12): 1704-1715 link data
  1. Legault, G., Melbourne, B. A. (2019) Accounting for environmental change in continuous-time stochastic population models. Theoretical Ecology 12(1): 31-48 link
    • Recommended ("Very Good") by Faculty of 1000 Prime Access the recommendation on F1000Prime

2018 and before

  1. Contributing author (2018) "Direct and indirect drivers of land degradation and restoration" in Assessment Report on Land Degradation and Restoration. Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) link
  1. Legault, G., Cusa, M. (2015) Temperature and delayed snowmelt jointly affect the vegetative and reproductive phenologies of four sub-Arctic plants. Polar Biology 38: 1701-1711 link
  1. Fox, J., Legault, G., Vasseur, D., Einarson, J. (2013) Nonlinear effect of dispersal rate on spatial synchrony of predator-prey cycles. PLoS ONE 8(11): e379527 link
  1. Legault, G., Weis, A. (2013) The impact of snow accumulation on a heath spider community in a sub-Arctic landscape. Polar Biology 36: 885-894 link

Submitted

  • Legault, G., Bitters, M. E., Hastings, A., Melbourne, B. A. Interspecific competition slows range expansion and shapes range boundaries.

In preparation

  • Dallas, T., Legault, G., Melbourne, B. A., Hastings, A. Context-dependent dispersal in two species communities.
  • Legault, G., Riley, M. J., Melbourne, B. A. Intrinsic dispersal ability and environment affect trait evolution during range expansion.

Resources

Data

  • From Legault and Kingsolver 2020: R Scripts for simulating stochastic model of insect development. Click here to download repository
  • From Legault et al 2019: R Scripts for simulating stochastic consumer-resource model. Click here to download repository

Emacs

I do many of my tasks (e.g., R coding, writing, tracking RSS feeds, this website) within the venerable text editor Emacs.

As I am sometimes asked about getting started with Emacs, I've created a basic introduction to it, available here.