Pushed and pulled: looking back on a decade of exploring spatial dynamics and eco-evo feedbacks on invasion fronts

Abstract :

Population range expansions can be classified as pulled or pushed, based on the parameters that predict their expansion speed. In pulled expansions, the rate of spread is set solely by dynamics at the leading edge; in pushed expansions, the entire population core contributes to driving the front forward. This difference is not merely semantic but reflects fundamentally distinct demographic mechanisms, most notably the presence of positive density-dependence in pushed expansions.
Using combined approaches of mathematical modelling and experimental microcosm expansions, we have investigated how pushed expansions arise, how they unfold across heterogeneous landscapes, and how they reshape eco-evolutionary dynamics throughout an invasion. Our findings reveal that pushed expansions are likely to be far more common in nature than previously appreciated, and that they can profoundly alter the trajectory and evolutionary fate of invading species.