Long-range dispersal promotes spatial synchrony but reduces the length and time scales of synchronous fluctuations

TL;DR

This study shows that rare long-range dispersal events in metapopulations increase overall synchrony and homogenize spatial patterns, while also reducing the time needed for populations to reach equilibrium.

Contribution

It demonstrates the significant impact of long-range dispersal on spatial synchrony and pattern properties, which is often overlooked in ecological models.

Findings

Long-range dispersal promotes spatial synchrony.

It decreases the size of out-of-phase population clusters.

It reduces the equilibration time of the metapopulation.

Abstract

Synchronous oscillations of spatially disjunct populations are widely observed in ecology. Even in the absence of spatially synchronized exogenous forces, metapopulations may synchronize via dispersal. For many species, most dispersal is local, but rare long-distance dispersal events also occur. While even small amounts of long-range dispersal are known to be important for processes like invasion and spatial spread rates, their potential influence on population synchrony is often overlooked, since local dispersal on its own can be strongly synchronizing. In this work, we investigate the effect of random, rare, long-range dispersal on the spatial synchrony of a metapopulation and find profound effects not only on synchrony but also on properties of the resulting spatial patterns. While controlling for the overall amount of emigration from each local subpopulation, we vary the fraction of dispersal that occurs locally (to nearest neighbors) versus globally (to random locations, irrespective of distance). Using a metric that measures the instantaneous level of global synchrony, we show that this form of long-range dispersal significantly favors the spatially synchronous state and homogenizes the population by decreasing the size of clusters of subpopulations that are out of phase with the rest of the metapopulation. Moreover, the addition of non-local dispersal significantly decreases the equilibration time of the metapopulation.