Anywhere but here: local conditions motivate dispersal in Daphnia.

Philip Erm,Ben L Phillips,Matthew D Hall

doi:10.7717/peerj.6599

Abstract

Dispersal is fundamental to population dynamics. However, it is increasingly apparent that, despite most models treating dispersal as a constant, many organisms make dispersal decisions based upon information gathered from the environment. Ideally, organisms would make fully informed decisions, with knowledge of both intra-patch conditions (conditions in their current location) and extra-patch conditions (conditions in alternative locations). Acquiring information is energetically costly, however, and extra-patch information will typically be costlier to obtain than intra-patch information. As a consequence, theory suggests that organisms will often make partially informed dispersal decisions, utilising intra-patch information only. We test this proposition in an experimental two-patch system using populations of the aquatic crustacean, Daphnia carinata. We manipulated conditions (food availability) in the population’s home patch, and in its alternative patch. We found that D. carinata made use of intra-patch information (resource availability in the home patch induced a 10-fold increase in dispersal probability) but either ignored or were incapable of using of extra-patch information (resource availability in the alternative patch did not affect dispersal probability). We also observed a small apparent increase in dispersal in replicates with higher population densities, but this effect was smaller than the effect of resource constraint, and not found to be significant. Our work highlights the considerable influence that information can have on dispersal probability, but also that dispersal decisions will often be made in only a partially informed manner. The magnitude of the response we observed also adds to the growing chorus that condition-dependence may be a significant driver of variation in dispersal.

Highlights

IntroductionLike survival and reproduction, is a fundamental facet of life history (Bonte & Dahirel, 2017)
Dispersal, like survival and reproduction, is a fundamental facet of life history (Bonte & Dahirel, 2017)
There is considerable evidence, that dispersal decisions are routinely informed by aspects of the environment (Clobert et al, 2009), with such information use expected to have non-negligible effects on ensuing population and evolutionary dynamics (Delgado et al, 2014; Ponchon et al, 2015; Urban et al, 2016)

Summary

Introduction

Like survival and reproduction, is a fundamental facet of life history (Bonte & Dahirel, 2017). Behaviours which govern dispersal can have profound consequences for a variety of biological and ecological phenomena, such as individual fitness, metapopulation dynamics, and evolutionary outcomes across a species’ range (Bonte & Dahirel, 2017; Clobert et al, 2001). Anywhere but here: local conditions motivate dispersal in Daphnia. There is considerable evidence, that dispersal decisions are routinely informed by aspects of the environment (Clobert et al, 2009), with such information use expected to have non-negligible effects on ensuing population and evolutionary dynamics (Delgado et al, 2014; Ponchon et al, 2015; Urban et al, 2016)

Methods

Results

Discussion

Conclusion