Notonecta Exhibit Threat-Sensitive, Predator-Induced Dispersal

Shannon J. McCauley, University of Toronto
Locke Rowe, University of Toronto

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Copyright © 2010 The Royal Society. The definitive version is available at http://dx.doi.org/10.1098/rsbl.2009.1082.

NOTE: At the time of publication, the author Shannon J. McCauley was not yet affiliated with Cal Poly.

Abstract

Dispersal is a central process determining community structure in heterogeneous landscapes, and species interactions within habitats may be a major determinant of dispersal. Although the effects of species interactions on dispersal within habitats have been well studied, how species interactions affect the movement of individuals between habitats in a landscape has received less attention. We conducted two experiments to assess the extent to which predation risk affects dispersal from an aquatic habitat by a flight-capable semi-aquatic insect (Notonecta undulata). Exposure to non-lethal (caged) fish fed conspecifics increased dispersal rates in N. undulata. Moreover, dispersal rate was positively correlated with the level of risk imposed by the fish; the greater the number of notonectids consumed by the caged fish, the greater the dispersal rate from the habitat. These results suggest that risk within a habitat can affect dispersal among habitats in a landscape and thus affect community structure on a much greater scale than the direct effect of predation itself.