title: Brain size affects female but not male survival under predation threat.
abstract: There is remarkable diversity in brain size among vertebrates, but surprisingly little is known about how ecological species interactions impact the evolution of brain size. Using guppies, artificially selected for large and small brains, we determined how brain size affects survival under predation threat in a naturalistic environment. We cohoused mixed groups of small- and large-brained individuals in six semi-natural streams with their natural predator, the pike cichlid, and monitored survival in weekly censuses over 5 months. We found that large-brained females had 13.5% higher survival compared to small-brained females, whereas the brain size had no discernible effect on male survival. We suggest that large-brained females have a cognitive advantage that allows them to better evade predation, whereas large-brained males are more colourful, which may counteract any potential benefits of brain size. Our study provides the first experimental evidence that trophic interactions can affect the evolution of brain size.
authors.affiliation: Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden.|Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstraße 1a, 1160-Vienna, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kotrschal
authors.affiliation: Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden.|Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstraße 1a, 1160-Vienna, Austria.
authors.forename: Séverine D
authors.initials: SD
authors.lastname: Buechel
authors.affiliation: Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstraße 1a, 1160-Vienna, Austria.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Zala
authors.affiliation: Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden.
authors.forename: Alberto
authors.initials: A
authors.lastname: Corral-Lopez
authors.affiliation: Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstraße 1a, 1160-Vienna, Austria.
authors.forename: Dustin J
authors.initials: DJ
authors.lastname: Penn
authors.affiliation: Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden.
authors.forename: Niclas
authors.initials: N
authors.lastname: Kolm
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D008297:Male; D009929:Organ Size; D011036:Poecilia / Q000033:anatomy & histology* / Q000502:physiology; D011157:Population Dynamics; D011235:Predatory Behavior; D012737:Sex Factors
keywords: Artificial selection; Crenicichla; Poecilia reticulata; brain size; guppy; pike cichlid; predation; semi natural; survival