Simulating predator attacks on schools: Evolving composite tactics

Jure Demsar*, Charlotte K. Hemelrijk, Hanno Hildenbrandt, Iztok Lebar Bajec

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

15 Citations (Scopus)
410 Downloads (Pure)

Abstract

One hypothesis about the origins and evolution of coordinated animal movements is that they may serve as a defensive mechanism against predation. Earlier studies of the possible evolution of coordinated movement in prey concentrated on predators with simple attack tactics. Numerous studies, however, suggest that to overcome the apparent defensive mechanisms which grouping and coordinated movement may provide to prey, predators in nature appear to use elaborate target selection and pursuit/hunting tactics. We here study predators that use composite tactics, (a) predators that in successive attacks based on probability choose one of several simple attack tactics, (b) predators that first disperse prey and then pick off isolated individuals. We develop an individual based model of a group of prey that is attacked by a solitary predator agent. By using genetic algorithms, we enable the predator agent to adapt (a) the probability that a specific tactic will be selected in the next attack, (b) the distance at which it stops dispersing the prey and the radius within which it searches for the most isolated prey. With a direct competition of the evolved predator agents we examine which is the better tactic against a group of prey moving in a polarized cohesive manner in three different settings. Our results suggest that, (a) a delayed response is an efficient advanced prey defence tactic, (b) predator confusion plays an important role in the evolution of composite tactics, and (c) when confusion is at play, the dispersing predator is a much better hunter, capable of at least partially diminishing the effectiveness of the prey's delayed response. (C) 2015 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)22-33
Number of pages12
JournalEcological Modelling
Volume304
Early online date22-Mar-2015
DOIs
Publication statusPublished - 24-May-2015

Keywords

  • Predator-prey interactions
  • Predator attack tactics
  • Individual based model
  • Predator tactic evolution
  • FISH SCHOOLS
  • SELFISH HERD
  • COLLECTIVE BEHAVIOR
  • TURSIOPS-TRUNCATUS
  • KILLER WHALES
  • PREY
  • MOTION
  • MODEL
  • SELECTION
  • ORGANIZATION

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