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Research Interests:
Research Interests:
My research is driven by the desire to understand the complex phenomena and interactions between processes that shape diversity patterns in natural systems. In my PhD, I use annual plants in the California serpentine to test and develop theory using simulations and empirical experiments to assess how the co-operation of core ecological processes (species requirements, species interactions, dispersal, stochasticity, and evolution) influence community, population, and individual responses to variability over time and space.
For a comprehensive list of my publications, click here.
J. J. Kowalski, B. Gilbert, S. Y. Strauss, & R. M. Germain (2025) Experimentally enhancing dispersal reveals the outsized importance of transient dynamics in a fluctuating environment. PNAS [link to pdf]
Field experiment:
Field experiment:
Experimentally enhancing dispersal reveals the outsized importance of transient dynamics in a fluctuating environment
Experimentally enhancing dispersal reveals the outsized importance of transient dynamics in a fluctuating environment
Summary: I investigate how the future impact of a historical dispersal event on community diversity and composition is mediated by shifts in climate. I find evidence that temporal lags direct community responses to climatic fluctuations by providing subordinate species discrete windows of time to supplement their seed banks. Overall a joint spatiotemporal equilibrium is revealed in this system where dispersal through space interacts with temporal fluctuations in climate to support species persistence via dormancy.
J. J. Kowalski, G. Gillies, & R. M. Germain [IN PREP]
Greenhouse experiment:
Greenhouse experiment:
The deterministic underpinnings of luck
The deterministic underpinnings of luck
Summary: I propose and test whether stochastic variation in population-level lifetime reproductive success (or luck at the individual level) can be influenced by an organism's biology. In doing so, I provide the first empirical evidence that chance variation in reproductive success is context-dependent. Specifically, I find that individual luck is affected by the alignment between when important life events occur and unpredictable changes in the environment.
I am presenting the results from this project at CSEE 2026 in Toronto, ON on May 14th! [link]
J. J. Kowalski, L. Hallett, & R. M. Germain [IN PREP]
Computer simulation:
Computer simulation:
Density lags provide windows of opportunity for invasion
Density lags provide windows of opportunity for invasion
Summary: I explore the trait combinations (i.e., r, K, alpha) within species pairs that ensure temporal density lags matter for invasibility and the outcome of coexistence in temporally fluctuating environments. I verify the existence of this "window of opportunity" mechanism in nature by performing the same analyses using data collected from species pairs located in regions where climate and weather patterns are highly variable.
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