title: Exploring the evolution of a trade-off between vigilance and foraging in group-living organisms.
abstract: Even though grouping behaviour has been actively studied for over a century, the relative importance of the numerous proposed fitness benefits of grouping remain unclear. We use a digital model of evolving prey under simulated predation to directly explore the evolution of gregarious foraging behaviour according to one such benefit, the 'many eyes' hypothesis. According to this hypothesis, collective vigilance allows prey in large groups to detect predators more efficiently by making alarm signals or behavioural cues to each other, thereby allowing individuals within the group to spend more time foraging. Here, we find that collective vigilance is sufficient to select for gregarious foraging behaviour as long there is not a direct cost for grouping (e.g. competition for limited food resources), even when controlling for confounding factors such as the dilution effect. Furthermore, we explore the role of the genetic relatedness and reproductive strategy of the prey and find that highly related groups of prey with a semelparous reproductive strategy are the most likely to evolve gregarious foraging behaviour mediated by the benefit of vigilance. These findings, combined with earlier studies with evolving digital organisms, further sharpen our understanding of the factors favouring grouping behaviour.
authors.affiliation: Department of Computer Science and Engineering , Michigan State University , East Lansing, MI 48824, USA ; BEACON Center for the Study of Evolution in Action , East Lansing, MI 48824, USA.
authors.forename: Randal S
authors.initials: RS
authors.lastname: Olson
authors.affiliation: Department of Computer Science , The University of Texas at Austin , Austin, TX 78712, USA ; BEACON Center for the Study of Evolution in Action , East Lansing, MI 48824, USA.
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Haley
authors.affiliation: Department of Zoology , Michigan State University , East Lansing, MI 48824, USA ; BEACON Center for the Study of Evolution in Action , East Lansing, MI 48824, USA.
authors.forename: Fred C
authors.initials: FC
authors.lastname: Dyer
authors.affiliation: Department of Microbiology and Molecular Genetics , Michigan State University , East Lansing, MI 48824, USA ; BEACON Center for the Study of Evolution in Action , East Lansing, MI 48824, USA.
authors.forename: Christoph
authors.initials: C
authors.lastname: Adami
keywords: anti-predator vigilance; genetic relatedness; group foraging; many eyes hypothesis; reproductive strategy; tragedy of the commons