Behavioral Ecology Advance Access published online on May 19, 2008
Behavioral Ecology, doi:10.1093/beheco/arn055
Evolutionarily costly courtship displays in a wolf spider: a test of viability indicator theory
a Department of Zoology, Miami University, Oxford, OH 45056, USA b Department of Biology, Susquehanna University, Selinsgrove, PA 17870, USA c Department of Zoology, Miami University, Hamilton, OH 45011, USA
Address correspondence to C.D. Hoefler. E-mail: hoeflerc{at}arcadia.edu.
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Abstract |
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The costs of secondary sexual traits are crucial to our understanding of sexual selection. Although it is broadly accepted that sexual traits are indirectly or directly costly to express, few studies have quantified such costs. Thus, it is unclear if costs are evolutionarily meaningful and to what degree. Costs play a key role in viability indicator models, which assume that 1) the expression of sexual traits reduces the fitness of the trait bearer, 2) sexual trait expression is dependent on condition, and 3) the costs of sexual trait expression are borne differentially, that is, they are less for individuals in good condition. Using 2 syntopic species of wolf spiders, we addressed the importance of direct predation costs on the viability indicator mechanism. Pardosa milvina is a small wolf spider that has conspicuous male courtship behaviors in the form of front leg raises. Hogna helluo is a large species that preys on P. milvina. In laboratory experiments, we discovered that predation risk from H. helluo was higher for courting P. milvina males than noncourting males, male P. milvina manipulated to be in good condition courted at higher rates than males manipulated to be in poor condition, and males in good condition survived predation risk better than males in poor condition. Our study suggests that predation is a significant, evolutionary cost that can satisfy viability indicator mechanism assumptions.
Key words: costs, courtship, Lycosidae, predation, sexual selection, spider.
Received 19 July 2007; revised 9 April 2008; accepted 18 April 2008.