How does temporal variation influence the eco-evolutionary dynamics of range limits?— Messages from source-sink models
Robert D. Holt, University of Florida, USA
Temporal variation is ubiquitous in nature and can lead to variation in birth, death, or dispersal rates. A well-established result in conservation biology is that temporal variation can enhance extinction risk, particularly in populations low in abundance. One might thus expect that along environmental gradients, temporal variation might lead to shrinkage in species ranges. In this talk, we will present models suggesting the opposite might at times be true. Models for adaptive evolution in source-sink systems (with either clonal variation, or quantitative genetic variation, using both analytical models and individual-based simulations) reveal that moderate fluctuations in birth, death, or dispersal rates can at times facilitate adaptation to a sink habitat. Interactions with other species (e.g., competitors, natural enemies, mutualists) can provide a particularly potent source of temporal variation in demographic parameters, with implications for the interplay of community interactions and evolution in determining species’ range limits along environmental gradients.