title: Why do female Callosobruchus maculatus kick their mates?
abstract: Sexual conflict is now recognised as an important driver of sexual trait evolution. However, due to their variable outcomes and effects on other fitness components, the detection of sexual conflicts on individual traits can be complicated. This difficulty is exemplified in the beetle Callosobruchus maculatus, where longer matings increase the size of nutritious ejaculates but simultaneously reduce female future receptivity. While previous studies show that females gain direct benefits from extended mating duration, females show conspicuous copulatory kicking behaviour, apparently to dislodge mating males prematurely. We explore the potential for sexual conflict by comparing several fitness components and remating propensity in pairs of full sibling females where each female mated with a male from an unrelated pair of full sibling males. For one female, matings were terminated at the onset of kicking, whereas the other's matings remained uninterrupted. While fecundity (number of eggs) was similar between treatments, uninterrupted matings enhanced adult offspring numbers and fractionally also longevity. However, females whose matings were interrupted at the onset of kicking exhibited an increased propensity to remate. Since polyandry can benefit female fitness in this species, we argue that kicking, rather than being maladaptive, may indicate that females prefer remating over increased ejaculate size. It may thus be difficult to assess the presence of sexual conflict over contested traits such as mating duration when females face a trade off between direct benefits gained from one mating and indirect benefits from additional matings.
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, Australia.
authors.forename: Emile
authors.initials: E
authors.lastname: van Lieshout
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, Australia.
authors.forename: Kathryn B
authors.initials: KB
authors.lastname: McNamara
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, Australia.
authors.forename: Leigh W
authors.initials: LW
authors.lastname: Simmons
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D005260:Female; D008297:Male; D012098:Reproduction / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology*
references.citation: Heredity (Edinb). 2009 Oct;103(4):340-5
references.pmid: 19639006
references.citation: Proc Biol Sci. 2003 Mar 22;270(1515):653-64
references.pmid: 12769467
references.citation: Curr Biol. 2012 Dec 4;22(23):2258-61
references.pmid: 23103188
references.citation: Evolution. 2000 Dec;54(6):2161-5
references.pmid: 11209792
references.citation: Philos Trans R Soc Lond B Biol Sci. 2006 Feb 28;361(1466):301-17
references.pmid: 16612889
references.citation: J Insect Physiol. 2008 Dec;54(12):1522-7
references.pmid: 18831977
references.citation: Science. 2009 Jun 26;324(5935):1705-6
references.pmid: 19556506
references.citation: Evolution. 2011 Aug;65(8):2171-83
references.pmid: 21790567
references.citation: Biol Rev Camb Philos Soc. 2010 Nov;85(4):897-934
references.pmid: 20560928
references.citation: J Theor Biol. 2005 Feb 7;232(3):443-9
references.pmid: 15572067
references.citation: Nature. 2000 Oct 19;407(6806):855-6
references.pmid: 11057654
references.citation: Proc Biol Sci. 2010 May 7;277(1686):1371-6
references.pmid: 20053645
references.citation: Nature. 2002 Feb 14;415(6873):787-9
references.pmid: 11845208
references.citation: Evolution. 2014 Sep;68(9):2550-8
references.pmid: 24724572
references.citation: Proc Biol Sci. 2007 Jan 22;274(1607):247-52
references.pmid: 17035168
references.citation: Curr Biol. 2009 Mar 10;19(5):404-7
references.pmid: 19230665
references.citation: Anim Behav. 1999 Sep;58(3):669-675
references.pmid: 10479383