Within-population variation is ubiquitous. Some variation is fixed for life (e.g., genotype, birth weight). Other kinds of variation change over time (size, breeding status, diet specialization) in a mix of determinism and chance, so that the life of an individual is a walk through a garden of forking paths. Understanding the causes of this within-population variation, and its ecological consequences for individuals, populations, and communities, is an ongoing challenge for ecologists.
Much of my research career has focused on these questions, and on the development of new modeling approaches to address them theoretically. My poster will focus on two recent papers.
Results/Conclusions
Heritable variation: evolution on ecological time-scales has transitioned, within my research lifespan, from fringe to dogma in ecology. The standard model of evolution at the molecular level has no room for this -- adaptive change occurs in rare selective sweeps and standing genetic variation is neutral "noise" or deleterious mutations not yet purged. Despite decades of asking, we still don't understand how populations can so often have the genetic wherewithal for extremely quick adaptive evolution. Recent work with Mark Rees, combining structured projection models with quantitative genetic models for life history traits, suggests that we (including myself) have been dramatically underestimating the potential for temporally fluctuating selection to maintain genetic variance.
Dynamic variation: When we model disease transmission in multi-species communities, transmission is typically based on species-level contact networks. But disease spreads from individual to individual, not species to species, and the ubiquity of individual-level diet or habitat specializations means that individual-level contact networks may be systematically different from species-level networks. As a result, models based on species-level contact networks can be dramatically wrong about the potential for persistence and spread of a pathogen in a multi-species disease system.