Mitocondrias

2011. The Journal of Arachnology 39:161–165

Contrasting energetic costs of courtship signaling in two wolf spiders having divergent courtship behaviors
Alan B. Cady1,4, Kevin J. Delaney2,3 and George W. Uetz3: 1Department of Zoology, Miami University, Oxford, Ohio
45056 USA; 2Current address: Department of Land Resources and Environmental Sciences, 334 Leon Johnson Hall,
Montana StateUniversity, Box 173120, Bozeman, MT 59717-3120 USA; 3Department of Biological Sciences,
University of Cincinnati, Cincinnati, Ohio, 45221 USA
Abstract. Energetic costs of courtship behavior were measured for two sympatric wolf spiders that are reproductively
isolated based on distinct male courtship behaviors with different signaling modes and activity levels: Schizocosa ocreata
(Hentz 1844) usesmulti-modal communication (visual and seismic signals) and an actively-moving courtship display,
whereas S. rovneri (Uetz & Dondale 1979) uses only seismic signals produced while stationary. To test for increased
energetic expense of more complex multimodal courtship in S. ocreata, we recorded peak CO2 output for male spiders
standing, walking, or courting. We found that peak CO2 output whilestanding or walking was similar between species.
Courtship behavior of S. ocreata produced greater peak CO2 output than these other behaviors, and was significantly
greater than peak CO2 output of S. rovneri courtship, which was not different from that of locomotion. Hence, unequal
energy expenditure related to the modality of the males’ courtship displays resulted in different energetic costsfor courting
male spiders. Male courtship vigor may serve as a criterion for female mate choice in Schizocosa.
Keywords:

Courtship, energetics, Schizocosa, respiration, sexual selection

several studies suggest that highly active multimodal signaling
may be more costly (Delaney et al. 2007; Roberts et al. 2007;
Uetz et al. 2009). In this study, we test this hypothesis by
examining theenergetic costs of courtship display for two
well-studied sibling species: Schizocosa ocreata (Hentz 1844)
and S. rovneri (Uetz & Dondale 1979). Given the observed
active, multimodal courtship of S. ocreata versus the more
stationary, unimodal courtship of S. rovneri (Delaney et al.
2007; Uetz et al. 2009), we predicted that S. ocreata will incur
higher energetic costs than its sibling species.INTRODUCTION
Differences in male courtship displays between spider
species may serve as behavioral isolating mechanisms for
closely-related taxa (Stratton & Uetz 1981, 1986; Miller et al.
1998; Stratton 2005), but may also reflect the influence of
sexual selection based in part on differential energetic costs
(Kotiaho et al. 1998; Parri et al. 2002; Delaney et al. 2007;
Byers et al.2010). Much support for ‘‘handicap’’ or ‘‘good
genes’’ models of sexual selection suggests that females prefer
males capable of sustaining higher levels of energetically costly
motor performance (see review by Byers et al. 2010), because
active, complex courtship display behaviors provide ‘‘honest’’
information to females about male condition or quality (e.g.,
Zahavi 1975; Zuk 1991; Andersson1994; Kotiaho et al. 1996,
1998). For example, in the well-studied European wolf spider
Hygrolycosa rubrofasciata (Ohlert 1865), females choose males
on the basis of drumming rates, which are good predictors of
male condition and viability (Kotiaho et al. 1996; Kotiaho et
al. 1998; Kotiaho 2000; Ahtianen et al. 2005, 2006).
Wolf spiders (Lycosidae) use active courtship displays and
multimodalcommunication (visual and seismic cues) to
varying degrees (Kotiaho et al. 1998; Hebets & Uetz 1999;
Hebets et al. 2006; Uetz & Roberts 2002; Uetz et al. 2009).
Within the genus Schizocosa, the S. ocreata clade contains 6–8
species that apparently have arisen via behavioral isolation
driven by sexual selection (Miller et al. 1998; Stratton 2005).
Members of this clade are similar in size...