The Interaction of Female Condition and Mating Status on Male-Male Aggression in a Wolf Spider Chad D. Hoefler*, Gayatri Guhanarayan*, Matthew H. Persons & Ann L. Rypstraà * Center for Animal Behavior and Department of Zoology, Miami University, Oxford, OH, USA  Department of Biology, Susquehanna University, Selinsgrove, PA, USA à Center for Animal Behavior and Department of Zoology, Miami University, Hamilton, OH, USA Introduction The evolution of fighting behavior has been exten- sively studied over a period of decades with a strong focus on male-male competition for resources. The development of game theory and the concept of evo- lutionarily stable strategies has helped clarify the logic of male contests (Maynard Smith & Price 1973; Maynard Smith 1974, 1982), and theorists and empiricists have identified many of the predictors of winners within contests (Parker 1974; Maynard Smith & Parker 1976; Parker & Rubenstein 1981; Austad 1983; Enquist & Leimar 1987; Dodson & Beck 1993; Hack et al. 1997; Hsu & Wolf 1999; Hoe- fler 2002; Lindstro ¨ m & Pampoulie 2005; Gherardi 2006). Males often compete over resources (e.g., potential mates, foraging areas, nest sites) that directly or indirectly affect fitness (Trivers 1972; Andersson 1994). However, intense male-male competition is expected when mating opportunities are limited and ⁄ or when females vary in quality and can be assessed based upon features that indicate potential reproductive success (Turner & Hunting- ford 1986; Andersson 1994). Because agonistic contests can be metabolically costly and lead to risks of injury and ⁄ or predation (Huntingford & Turner 1987; Marden & Waage 1990; Hack 1997; Sneddon et al. 1999), it is expected that individuals will modulate their contest effort according to the competitive context; i.e. selec- tion should favor individuals that adjust their fight- ing effort following resource value assessment (as well as their own fighting ability) (Parker 1974; Maynard Smith & Parker 1976; Parker & Stuart; Arnott & Elwood 2007, 2008). Game theory models demonstrate that fighting costs will increase with the Correspondence Chad D. Hoefler, Department of Biology, Arcadia University, Glenside, PA 19038, USA. E-mail: hoeflerc@arcadia.edu Received: July 29, 2008 Initial acceptance: October 23, 2008 Final acceptance: November 25, 2008 (D. Zeh) doi: 10.1111/j.1439-0310.2009.01627.x Abstract Fighting behavior has been studied extensively with strong emphases on factors that independently determine winners and losers as well as how much effort an individual should invest in a given contest for a resource. Much less attention has been paid to how interacting qualities of disputed resources modulate aggression. In a laboratory study, we examined the interactive effects of female condition and mating status on dyadic male aggression in the wolf spider Pardosa milvina. We discov- ered that males exhibited significantly more aggressive behaviors when in the presence of virgin females in good condition and displayed lower and statistically similar levels of aggression when placed with virgin, poor condition females; mated, good condition females; mated, poor condition females; and no females. Because previous studies have sug- gested that virgin females alone should be highly prized because of putative first-mate sperm priority patterns, this study contributes to this body of literature by suggesting that diet history and body condition mitigate the reproductive advantages of mating with virgin females as indicated by levels of male-male aggression, but further investigation is needed. Ethology Ethology 115 (2009) 331–338 ª 2009 Blackwell Verlag GmbH 331