The effect of landscape structure on the evolution of two alternative dispersal strategies

Abstract

Background Dispersal is an important event for most organisms at least once in their life cycle. The evolution of dispersal can be influenced by local adaptation, landscape structure, and perceived temporal and spatial variation. The interaction between local adaptation, landscape heterogeneity, temporal variability and rules of dispersal may be more complex than previously assumed. Therefore, we sought to understand the influence of emigration rules and landscape structure on emerging dispersal rates and traits. Here, we implemented an individual-based model (IBM) of trait evolution in scenarios characterized by different landscape structures and different degrees of spatial heterogeneity and global temporal variation. Individuals could evolve two traits coding for their environmental niche (position of niche optimum and niche width), and two traits determining nearest-neighbor dispersal: an individual emigrates with a probability defined by the first trait (random emigration), but emigrates with certainty if the fertility expected in the patch of residence falls below a threshold specified by the second trait (habitat-dependent emigration). Results We note an interaction effect between dispersal strategy and spatial variance—lower emigration under habitat-dependent than under random emigration if spatial heterogeneity is low, but eventually a reversal of this ranking if heterogeneity becomes large. Landscapes with sharp transition of habitat attributes result in a high degree of spatial sorting, while fractal landscapes do not. Emigration rates are overall lowest, when spatial variation is highest. Conclusions We conclude that emergent emigration rates are influenced more by landscape structure and spatio-temporal heterogeneity than by the emigration strategy. With the ongoing land use change more research into this topic could help highlight the difficulties species might face under the change from landscapes characterized by gradual transition zones to landscapes dominated by abrupt ecotones, the latter typical for agricultural and urban settings.

Effects of compositional heterogeneity and spatial autocorrelation on richness and diversity in simulated landscapes

“…As such, fitness, and therefore population persistence, will be highly sensitive to spatial context. Informed and directed dispersal has the potential to greatly reduce the risks of dispersal (Lakovic et al., 2015 ), enabling more frequent dispersal in otherwise high‐risk spatial contexts (Sieger & Hovestadt, 2021 ). Directed long‐distance dispersal could improve population persistence in the landscape by facilitating colonization of otherwise isolated patches, but it could also reduce β‐diversity by allowing competitively dominant species to spread to suitable habitat more easily in more fragmented landscapes (Catano et al., 2017 ; Grainger & Gilbert, 2016 ).…”