Research themes
Species range dynamics under global change
How will species shift their geographical range in response to environmental change?
What are the ecological and molecular mechanisms that allow populations to spread and invade?
What limits a species geographical range and ecological niche?
Understanding the ecological and evolutionary processes that shape species distributions and their limits is a fundamental goal of ecology, and an increasingly urgent one as global change rapidly reshapes species geographical ranges.
Range expansion and contraction can drive rapid evolutionary changes in range-edge populations, and these evolutionary changes can in turn shape subsequent range dynamics through eco-evolutionary feedbacks. Predicting species range dynamics under global change therefore requires an understanding of how spatial eco-evolutionary processes unfold across moving populations and under changing environments.
To explore these questions, we use a variety of experimental and molecular approaches in the lab and field, including experimental evolution of duckweeds in spatially structured microcosms, mesocosms, and ponds. Together, these approaches allow us to manipulate and track how populations move and evolve across space and in real-time (see Approaches).
From Usui & Angert (2024) Ecol. Lett.
Eco-evolutionary dynamics of competition and
species coexistence
How will eco-evolutionary responses to global change unfold within competitive communities?
How does competition alter species range dynamics and spatial patterns of coexistence?
How will species evolve to coexist during community (re-)assembly?
(from Usui & Angert (2026) Science)
Species rarely experience environmental change in isolation. Instead, eco-evolutionary responses to environmental change occur within a community context where interacting and competing species have the potential to alter population, evolutionary, and community outcomes.
Through merging experimental evolution with community ecology, our lab seeks to understand the reciprocal interactions between competition and evolution, asking: (1) when and how does competition alter evolutionary responses to environmental change? And, in turn, (2) how does evolution alter mechanisms of competition, species coexistence, and community assembly?
Ultimately, we seek to understand how competition and evolution interact across landscapes and over time to shape where species occur, how they coexist, and how communities respond to rapid environmental change.
Eco-evolutionary dynamics of plant-microbe interactions
How do plant-microbe interactions co-evolve across space and with environmental change?
How do microbial symbionts alter host evolution, distribution, and coexistence?
How does the microbiome assemble on host plants?
Almost all eukaryotic organisms harbour microbial partners (symbionts) that live on or inside host tissues. These microbial partners can alter host performance and vice versa, with interactions spanning from mutualism to antagonism. How host-microbe interactions change and co-evolve—and how these interactions help shape host and microbial distribution, coexistence, and rapid evolution in response to environmental change—remain key, open questions.
The microbes residing in and on duckweeds have been described since the 17th century. We use duckweeds and their microbial symbionts as a powerful and tractable model system for studying plant-microbial interactions. By combining lab and field experiments with molecular tools and high-throughput phenotyping (see Approaches), we can test fundamental questions on the eco-evolutionary processes shaping plant-microbe interactions, and how these interactions consequently shape large-scale patterns of biodiversity.
(from Usui et al. (2026) New Phyt)