Guilhem Doulcier

Ecological scaffolding of collective-level properties and the Goldilocks zone of ETIs

Evolutionary transitions in individuality (ETIs), such as the emergence of multicellularity, are events in the history of life during which entities at one level of organization form collective-level entities that subsequently become individuals in their own right. The “Ecological Scaffolding scenario” is a unifying theme for a series of research question in the study of ETIs that revolves around the role of an externally imposed meta-population structure, with renewing patches of resources and limited dispersal. When the “scaffolding conditions” are fulfilled, colonization of new patches and the extinction of existing populations within old patches creates a birth-death process at the population level. This collective birth-death process provides an opportunity for natural selection to promote beneficial traits at the collective level, and thus initiate ETIs. I will present a stochastic eco-evolutionary model of the scenario, and its adaptive dynamics analysis to better characterize the conditions for ecological scaffolding. Additionally, we will see how given the presence of an environmental gradient of externally imposed meta-population structure, ecological scaffolding can be limited to relatively small ``Goldilocks’’ zones in which the aforementioned conditions are fulfilled. We conjecture that Goldilocks zones could act as initiators of ETIs and help explain the near ubiquity of collective-level individuality, even if the conditions that promote it prove to be rare.