Code for:

Fronhofer, E. A., Nitsche, N. & Altermatt, F. Information use shapes range expansion dynamics into environmental gradients. Global Ecology and Biogeograohy

Abstract:

Aim: Globally, geographic distributions of species are dynamic and strongly influenced by dispersal. At the same time, range dynamics feed back and may select for increased dispersal at expanding range fronts. This interplay between macroecological and evolutionary dynamics almost universally happens across environmental gradients and such gradients can directly impact the fitness of organisms due to the match or mismatch between an individual's environmental optimum and the current conditions along the gradient. Importantly, gradients also provide individuals with information on the environmental changes because dispersing individuals may sense whether environmental conditions improve or deteriorate. However, the organisms' ability to use this information on the environment and to subsequently adjust dispersal decisions plastically, that is, deciding to further disperse into the gradient or not, has been largely ignored and the macroecological consequences remain unclear. We here aim at demonstrating the impact of informed dispersal on the eco-evolutionary dynamics of ranges.

Location: Laboratory and theoretical.

Methods: We used individual-based simulations and controlled experiments in replicated microcosm landscapes. Range expansions of the protist model organism Tetrahymena were tracked using video recording and analysis.

Results: We show that information on environmental gradients severely impacted range dynamics and inverted the spatial distribution of population densities in comparison to controls where this information was not provided. Additionally, using information on gradients prevented evolutionary changes in dispersal rates and an acceleration of range expansions.

Main conclusions: We demonstrate the strong impact of informed dispersal and subsequent behavioral changes on range dynamics in environmental gradients. More generally, our findings highlight the importance of informed dispersal for spatial ecological and evolutionary dynamics.