Abstract

Recent findings suggest that the colonization of habitat patches may be affected by the quality of surrounding patches. For instance, patches that lack predators may be avoided when located near others with predators, a pattern known as risk contagion. Alternatively, predator avoidance might also redirect dispersal towards nearby predator-free patches resulting in so-called habitat compression. However, it is largely unknown how predators continue to influence these habitat selection behaviours at increasing distances from outside of their own habitat patch. In addition, current information is derived from artificial mesocosm experiments, while support from natural ecosystems is lacking. This study used bromeliad landscapes as a natural model system to study how oviposition habitat selection of Diptera responds to the cues of a distant predator, the carnivorous elephant mosquito larva. We established landscapes containing predator-free bromeliad habitat patches placed at increasing distances from a predator-containing patch, along with replicate control landscapes. These patches were then left to be colonized by ovipositing bromeliad insects. We found that distance to predators modulates habitat selection decisions. Moreover, different dipteran families had different responses suggesting different habitat selection strategies. In some families, predator-free patches at certain distances from the predator patch were avoided, confirming risk contagion. In other families, these patches received higher numbers of colonists providing evidence of predator-induced habitat compression. We confirm that effects of predators in a natural ecosystem can extend beyond the patch in which the predator is present and that the presence or absence of remote predator effects on habitat selection depends on the distance to predators. The notion that perceived habitat quality can depend on conditions in neighbouring patches forces habitat selection studies to adopt a landscape perspective and account for the effects of both present and remote predators when explaining community assembly in metacommunities.

Highlights

  • Habitat selection is a well-documented phenomenon in actively dispersing organisms whereby environments deemed to maximize their fitness are preferentially colonized (Fretwell & Lucas, 1970; Morris, 2003)

  • We confirm that effects of predators in a natural ecosystem can extend beyond the patch in which the predator is present and that the presence or absence of remote predator effects on habitat selection depends on the distance to predators

  • Context dependency may arise when perception of target patch quality varies depending on the quality of nearby patches, a process known as spatial contagion, or from habitat compression, when patch colonization rates are elevated due to avoidance of nearby habitat patches (Resetarits, Binckley, & Chalcraft, 2005)

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Summary

| INTRODUCTION

Habitat selection is a well-documented phenomenon in actively dispersing organisms whereby environments deemed to maximize their fitness are preferentially colonized (Fretwell & Lucas, 1970; Morris, 2003). At one particular distance from a predator it is expected that prey behave either by contagion or compression, both types of context-dependent habitat selection may be observed across a landscape Previous studies of these remote predator effects on habitat selection have placed patches at a single distance from one another. Depending on how susceptible they are to predation or on their capacity to reach distant patches, colonists may divert to neighbouring patches (habitat compression) or patches beyond the experimental landscapes In this context, simple natural model systems that combine realism with experimental control can play an important role in confirming that a process is relevant in real ecosystems (Srivastava et al, 2004). (H4) we expected that different taxa might show different oviposition patterns in response to remote predator cues

| MATERIALS AND METHODS
Findings
| DISCUSSION

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