title: The Evolution of Lateralization in Group Hunting Sailfish.
abstract: Lateralization is widespread throughout the animal kingdom [1-7] and can increase task efficiency via shortening reaction times and saving on neural tissue [8-16]. However, lateralization might be costly because it increases predictability [17-21]. In predator-prey interactions, for example, predators might increase capture success because of specialization in a lateralized attack, but at the cost of increased predictability to their prey, constraining the evolution of lateralization. One unexplored mechanism for evading such costs is group hunting: this would allow individual-level specialization, while still allowing for group-level unpredictability. We investigated this mechanism in group hunting sailfish, Istiophorus platypterus, attacking schooling sardines, Sardinella aurita. During these attacks, sailfish alternate in attacking the prey using their elongated bills to slash or tap the prey [22-24]. This rapid bill movement is either leftward or rightward. Using behavioral observations of identifiable individual sailfish hunting in groups, we provide evidence for individual-level attack lateralization in sailfish. More strongly lateralized individuals had a higher capture success. Further evidence of lateralization comes from morphological analyses of sailfish bills that show strong evidence of one-sided micro-teeth abrasions. Finally, we show that attacks by single sailfish are indeed highly predictable, but predictability rapidly declines with increasing group size because of a lack of population-level lateralization. Our results present a novel benefit of group hunting: by alternating attacks, individual-level attack lateralization can evolve, without the negative consequences of individual-level predictability. More generally, our results suggest that group hunting in predators might provide more suitable conditions for the evolution of strategy diversity compared to solitary life.
authors.affiliation: Center for Adaptive Rationality, Max Planck Institute for Human Development, Lentzeallee 94, 14195 Berlin, Germany; Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm 310, 12587 Berlin, Germany. Electronic address: kurvers@mpib-berlin.mpg.de.
authors.forename: Ralf H J M
authors.initials: RHJM
authors.lastname: Kurvers
authors.affiliation: Department of Electrical Engineering and Computer Science, Lübeck University of Applied Sciences, 23562 Lübeck, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Krause
authors.affiliation: Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm 310, 12587 Berlin, Germany; Faculty of Life Sciences, Albrecht Daniel Thaer-Institut, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Viblanc
authors.affiliation: Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden; Department of Mathematics, Uppsala University, 751 05 Uppsala, Sweden.
authors.forename: James E
authors.initials: JE
authors.lastname: Herbert-Read
authors.affiliation: Julius Wolff Institut, Charité - Universitätsmedizin Berlin, Föhrer Str. 15, 13353 Berlin, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Zaslansky
authors.affiliation: IAMC-CNR, Istituto per l'Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche, Località Sa Mardini, 09170 Torregrande, Oristano, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Domenici
authors.affiliation: IAMC-CNR, Istituto per l'Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche, Località Sa Mardini, 09170 Torregrande, Oristano, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Marras
authors.affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark.
authors.forename: John F
authors.initials: JF
authors.lastname: Steffensen
authors.affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark.
authors.forename: Morten B S
authors.initials: MBS
authors.lastname: Svendsen
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building A08, Sydney, NSW 2006, Australia.
authors.forename: Alexander D M
authors.initials: ADM
authors.lastname: Wilson
authors.affiliation: Département du Master Sciences de l'Univers, Environnement, Écologie, Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Couillaud
authors.affiliation: Department of Biological Sciences, Florida International University, 3000 N.E. 151(st) Street, North Miami, FL 33181, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Boswell
authors.affiliation: Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm 310, 12587 Berlin, Germany; Faculty of Life Sciences, Albrecht Daniel Thaer-Institut, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Krause
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005399:Fishes; D020387:Food Chain; D007839:Functional Laterality; D010473:Perciformes / Q000502:physiology*; D011235:Predatory Behavior; D012919:Social Behavior
keywords: group hunting; handedness; laterality; predator-prey interactions; sailfish; strategy diversity