February 4 2019

12:00 Hershey Hall 158

William Petry
Institute for Integrative Biology, Plant Ecology, Princeton University and ETH Zurich

Integrating Demography Across Scales to Predict the Persistence and Coexistence of Species in Changing Environments


Populations are composed of individuals that vary in ecologically important traits, and likewise, communities are composed of heterogeneous species. It’s the differences between the components of these systems that give rise to biodiversity patterns in nature; however, the dynamics and ultimate stability of a system at either scale will rarely emerge from the sum of its parts. Instead, interactions among organisms induce feedbacks that can fundamentally alter the composition and persistence of populations and communities. Understanding the rules that govern diversity and its dynamic consequences is a grand challenge in ecology, one that reaches across scales of ecological organization and is made increasingly important by changing climate and the extinctions and redistributions of organisms.

In this talk, I will share two vignettes from my research that is uncovering the rules that structure ecological diversity over space and time. First, I’ll show how climate gradients and climate change skew the population sex ratios of a long-lived plant through sex-specific effects on individual plant performance. Pairing models with field data, not only reveals the demographic mechanisms that underlie this composition change, but also allows us to see how a biased sex ratio causes mate limitation, slows population growth, and may constrain responses to future climate change. The challenge of predicting the dynamics of ecological systems from their heterogeneous components, however, is not limited to the population scale. In the second part of my talk, I’ll focus on how we can adapt this approach to a community of annual plant species that share both resources and consumers (a harvester ant). Addressing the same challenge at a new scale reveals the mechanisms that maintain species diversity and produce mosaics of plant diversity across the landscape.

























































































































































































































































































































































































































































































































































































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