Beyond the mean: plant functional diversity and the maintenance of rare phenotypes in plant communities 

PIs: 

• Cyrille Violle, Centre d'Ecologie Fonctionnelle & Evolutive (CEFE), UMR5175
• Brian Enquist, Ecology & Evolutionary Biology (EEB), UArizona

Analyzing the drivers of the vulnerability of species and ecosystems to environmental changes is critical. Functional trait ecology has brought standardized protocols to analyze the response of numerous species on a physiological basis simultaneously. However, it lacks a theoretical corpus, which impedes a deep exploration of the underlying mechanisms and limits predictions. Rooted on adaptive dynamics theory, the team will focus on the dynamics of local physiological optima and community-level trait distributions (TD) around them and provide theoretical expectations. Using massive, ready-to-use, regional (France), and global databases of plant occurrences (herbs and trees), Dr. Violle and Dr. Enquist will empirically analyze the response of TDs along broad environmental gradients as well as over long-term time series. They will test whether species whose physiological features do not match local ecological optima in plant communities can persist or go extinct more rapidly, which is key for conservation programs.

Understanding how biodiversity and its various dimensions relate to the environment lies at the roots of ecology and is arguably the single most important step to understanding variations in ecosystem properties. Yet, this understanding remains fragmentary and inconsistent, seriously impeding our capacity to predict how ecological systems respond to changes, be they natural or human-induced, local or global. Biodiversity dynamics have had a long history of prioritized focus in ecology and evolution. Theories that focus on distributions of species abundances in space and time are numerous and have been highly influential. In the last 20 years, the trait-based perspective has gone from being an ad-hoc explanation of the statistical correlation between species richness and ecosystem functioning to becoming a dominant perspective in field and experimental studies. The functional trait approach promises a more mechanistic understanding of ecological processes, notably in community ecology. Profiling species on a physiological basis can help target species threatened to go extinct, as well as predict the response of communities to environmental changes. However, trait-based theory on biodiversity change and spatial processes are still largely underdeveloped.