title: Risky business for a juvenile marine predator? Testing the influence of foraging strategies on size and growth rate under natural conditions.
abstract: Mechanisms driving selection of body size and growth rate in wild marine vertebrates are poorly understood, thus limiting knowledge of their fitness costs at ecological, physiological and genetic scales. Here, we indirectly tested whether selection for size-related traits of juvenile sharks that inhabit a nursery hosting two dichotomous habitats, protected mangroves (low predation risk) and exposed seagrass beds (high predation risk), is influenced by their foraging behaviour. Juvenile sharks displayed a continuum of foraging strategies between mangrove and seagrass areas, with some individuals preferentially feeding in one habitat over another. Foraging habitat was correlated with growth rate, whereby slower growing, smaller individuals fed predominantly in sheltered mangroves, whereas larger, faster growing animals fed over exposed seagrass. Concomitantly, tracked juveniles undertook variable movement behaviours across both the low and high predation risk habitat. These data provide supporting evidence for the hypothesis that directional selection favouring smaller size and slower growth rate, both heritable traits in this shark population, may be driven by variability in foraging behaviour and predation risk. Such evolutionary pathways may be critical to adaptation within predator-driven marine ecosystems.
authors.affiliation: University of Windsor - Biological Sciences, Windsor, Ontario, N9B 3P4, Canada nehussey@uwindsor.ca.
authors.forename: Nigel E
authors.identifier: http://orcid.org/0000-0002-9050-6077
authors.initials: NE
authors.lastname: Hussey
authors.affiliation: Department of Environment and Agriculture, Curtin University, Perth, Western Australia 6845, PO Box U1987, Australia.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: DiBattista
authors.affiliation: Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Moore
authors.affiliation: Northwest Fisheries Science Center, 2725 Montlake Blvd East, Seattle, WA 98112, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Ward
authors.affiliation: Great Lakes Institute for Environmental Science, University of Windsor, Windsor, Ontario, Canada N9B 3P4.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Fisk
authors.affiliation: University of Windsor - Biological Sciences, Windsor, Ontario, N9B 3P4, Canada.
authors.forename: Steven
authors.initials: S
authors.lastname: Kessel
authors.affiliation: Bimini Biological Field Station Foundation, 15 Elizabeth Drive, South Bimini, Bahamas.
authors.forename: Tristan L
authors.initials: TL
authors.lastname: Guttridge
authors.affiliation: Pritzker Laboratory for Molecular Systematics and Evolution, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605, USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Feldheim
authors.affiliation: Department of Biology, Florida Southern College, Lakeland, FL, USA.
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Franks
authors.affiliation: Bimini Biological Field Station Foundation, 15 Elizabeth Drive, South Bimini, Bahamas.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Gruber
authors.affiliation: PSL Research University, EPHE-UPVD-CNRS, USR 3278 CRIOBE, Universite de Perpignan, 52 Avenue Paul Alduy, 66860 Perpignan Cedex, France.
authors.forename: Ornella C
authors.initials: OC
authors.lastname: Weideli
authors.affiliation: Institute for Ocean Conservation Science/School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000, USA.
authors.forename: Demian D
authors.initials: DD
authors.lastname: Chapman
mesh_terms: D000818:Animals; D001070:Appetitive Behavior; D017753:Ecosystem; D011235:Predatory Behavior; D012754:Sharks / Q000254:growth & development*
keywords: food web; lemon shark; life history; natural selection; predation risk; stable isotopes