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Régis Ferrière
Ecole Normale Supérieure, France
Ecological causes and consequences of evolution: Insights from adaptive dynamics
[When and where]
Ecological systems can be conceptualized as networks of biological populations interacting with one another; each population is a collection of phenotypically unique individuals. Historically, mathematical ecologists have sought to relate individual variation to population dynamics by using structured population models, in which individuals can transition between physiological, behavioral, or environmental states. Only relatively recently have genetically-based differences been considered, thus paving the way to exploring the interplay of ecological processes and evolution. Here I review the general mathematical framework that we currently have to model the “adaptive dynamics” of populations in which there is heritable variation in individual traits that have some impact on their demographic performance. I recall that starting from a “microscopic” individual-level stochastic description of the population, seven classes of models can be derived to describe the population’s “macroscopic” dynamics under alternate assumptions; one of them (the “Trait Substitution Sequence”) yields a rigorous definition of Darwinian fitness and selection gradient for general ecological scenarios. Continuity of the selection gradient with respect to the traits is often assumed, but I argue that discontinuity may not be rare. I highlight three remarkable consequences of discontinuity: evolutionary shifts between alternate ecological equilibria, evolutionary sliding along ecological bifurcations, and evolutionary diversification away from so-called branching points. These consequences are of interest to ecologists. Evolutionary shifts sheds light on patterns of rarity and commonness, and raise the possibility of evolution-driven extinction (evolutionary suicide) and rescue. Evolutionary sliding makes us expect critical transition regimes to be common in population dynamics. Evolutionary diversification away from branching points may occur when trait function is context-dependent; when applied to trophic interactions, this diversification process provides a new eco-evolutionary model for large-scale patterns of community functional diversity.
Keynote
Updated July 2, 2015, by Minus