title: A larger brain confers a benefit in a spatial mate search learning task in male guppies.
abstract: Brain size varies dramatically among vertebrates, and selection for increased cognitive abilities is thought to be the key force underlying the evolution of a large brain. Indeed, numerous comparative studies suggest positive relationships between cognitively demanding aspects of behavior and brain size controlled for body size. However, experimental evidence for the link between relative brain size and cognitive ability is surprisingly scarce and to date stems from a single study on brain size selected guppies (Poecilia reticulata), where large-brained females were shown to outperform small-brained females in a numerical learning assay. Because the results were inconclusive for males in that study, we here use a more ecologically relevant test of male cognitive ability to investigate whether or not a relatively larger brain increases cognitive ability also in males. We compared mate search ability of these artificially selected large- and small-brained males in a maze and found that large-brained males were faster at learning to find a female in a maze. Large-brained males decreased the time spent navigating the maze faster than small-brained males and were nearly twice as fast through the maze after 2 weeks of training. Our results support that relatively larger brains are better also for males in some contexts, which further substantiates that variation in vertebrate brain size is generated through the balance between energetic costs and cognitive benefits.
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University , Norbyvägen 18D, SE-75236 Uppsala , Sweden and ; Department of Zoology/Ethology, Stockholm University , Svante Arrheniusväg 18 B, SE-10691 Stockholm , Sweden.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kotrschal
authors.affiliation: Department of Zoology/Ethology, Stockholm University , Svante Arrheniusväg 18 B, SE-10691 Stockholm , Sweden.
authors.forename: Alberto
authors.initials: A
authors.lastname: Corral-Lopez
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University , Norbyvägen 18D, SE-75236 Uppsala , Sweden and.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Amcoff
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University , Norbyvägen 18D, SE-75236 Uppsala , Sweden and ; Department of Zoology/Ethology, Stockholm University , Svante Arrheniusväg 18 B, SE-10691 Stockholm , Sweden.
authors.forename: Niclas
authors.initials: N
authors.lastname: Kolm
keywords: brain size; cognition; guppy; maze.
references.citation: Behav Brain Res. 2004 Jul 9;152(2):351-60
references.pmid: 15196803
references.citation: J Fish Biol. 2009 Oct;75(6):1323-30
references.pmid: 20738617
references.citation: Biol Lett. 2011 Oct 23;7(5):730-2
references.pmid: 21525053
references.citation: Curr Biol. 2013 Jan 21;23(2):168-71
references.pmid: 23290552
references.citation: Am Nat. 2008 Jul;172 Suppl 1:S63-71
references.pmid: 18554145
references.citation: Proc Biol Sci. 2006 Mar 22;273(1587):719-24
references.pmid: 16608692
references.citation: Proc Natl Acad Sci U S A. 2014 May 20;111(20):E2140-8
references.pmid: 24753565
references.citation: Proc Biol Sci. 2001 Apr 22;268(1469):833-8
references.pmid: 11345329
references.citation: Evolution. 2008 Aug;62(8):2015-26
references.pmid: 18489718
references.citation: Psychon Bull Rev. 1996 Mar;3(1):21-36
references.pmid: 24214801
references.citation: J Hum Evol. 2009 Oct;57(4):392-400
references.pmid: 19732937
references.citation: Curr Biol. 2009 Nov 17;19(21):R995-R1008
references.pmid: 19922859
references.citation: Evolution. 2007 May;61(5):1162-75
references.pmid: 17492969
references.citation: Proc Biol Sci. 2007 Mar 22;274(1611):763-9
references.pmid: 17251112
references.citation: Oecologia. 2003 Sep;137(1):62-8
references.pmid: 12856201
references.citation: Nat Rev Neurosci. 2004 Jun;5(6):483-94
references.pmid: 15152198
references.citation: Annu Rev Neurosci. 2005;28:1-23
references.pmid: 15651931
references.citation: Brain. 2006 Feb;129(Pt 2):386-98
references.pmid: 16339797
references.citation: Evolution. 2014 Apr;68(4):1139-49
references.pmid: 24359469
references.citation: Trends Ecol Evol. 2000 Jul;15(7):296-299
references.pmid: 10856957
references.citation: Anim Behav. 2013 Oct;86(4):e4-e6
references.pmid: 24109149