Contrast influences female attraction to performance-based sexual signals in a songbird

Abstract

Animals do not make decisions in a bubble but often refer to previous experience when discriminating between options. Contrast effects occur when the value of a stimulus affects the response to another value of the stimulus, and the changes in value and response are in the same direction. Although contrast effects appear irrational, they could benefit decision makers when there is spatial or temporal variation and autocorrelation in the value of stimuli that elicit decisions. Here, we examined whether contrasts influence female evaluation of male performance-based sexual signals. We exposed female Lincoln's sparrows (Melospiza lincolnii) to one week of songs that we had experimentally reduced or elevated in performance, followed by a novel song of intermediate performance. We found that high-performance songs were more attractive to females than low-performance songs. Moreover, the intermediate songs were more attractive following exposure to low-than to high-performance songs. These results indicate that contrast can influence evaluation of performancebased sexual stimuli. By examining contrast effects in the ecologically relevant context of mate choice for performance, we can better understand both the adaptive value of comparative evaluation as well as the mechanisms that underlie variation in mate choice and sexual selection.

Sex Differences in Forebrain Monoaminergic Response to Song Performance

“…Several studies have found that extended exposure to songs of differing value influence neural activity and behavior in female and male songbirds. One week of experience with more attractive compared to less attractive songs increased neural discrimination for male song in the female European starling (Sturnus vulgaris) [Sockman et al, 2002;Sockman et al, 2005] and decreased behavioral responsiveness to male song in the female Lincoln's sparrow [Lyons et al, 2014], suggesting that long-term experience with attractive songs increases female discrimination of song attractiveness [Bateson and Healy, 2005;Sockman, 2007;Lyons et al, 2014]. At the same time, male songbirds that experienced 1 week of exposure to high-quality songs increased singing effort more than males that experienced low-quality songs, indicating that males increase competitive behavior in response to experience with competitive signals [Salvante et al, 2009;Sewall et al, 2013].…”

“…In songbirds, the function of songs in the external environment and the state of the internal environment differ between females and males that are reproductively ready [Searcy and Brenowitz, 1988;Nowicki and Searcy, 2004]. For females, high-performance songs are attractive [Caro et al, 2010;Lyons et al, 2014], whereas for males, high-performance songs are threatening [Illes et al, 2006]. The finding of an interactive effect of song performance and sex on monoaminergic activity in the auditory telencephalon gives rise to the hypothesis that the evolution of sex differences in behavioral responses to sexual signals is mediated, at least in part, by monoamines in perceptual regions of the brain.…”

“…Approximately 85 songs played per 20-min interval, and approximately 890 songs played over the entire 5.25 h of song exposure. Songs played at a peak amplitude of 70 dB 5 cm from the speaker [Sewall et al, 2013;Lyons et al, 2014].…”

“…Starting January 13, 2013, we switched 8 birds to a 16-h light:8-h dark photoperiod for 4 weeks in order to stimulate the development of reproductive behavior and physiology [Nicholls et al, 1988]. Previous studies have used similar photoperiod schedules to test sexual behavior in female [Caro et al, 2010;Lyons et al, 2014] and male Lyons, 2016] Lincoln's sparrows. Furthermore, photostimulation with long days has stimulated the development of reproductive physiology in other species of sparrows [e.g., Wingfield et al, 1997].…”

“…Furthermore, the valence of high-performance songs differs for females and males. Studies in multiple species of songbirds, including 2 studies in Lincoln's sparrows, indicate that females find high-performance songs more attractive than low-performance songs [Ballentine et al, 2004;Caro et al, 2010;Lyons et al, 2014], while male songbirds, including Lincoln's sparrows, are more threatened by and aggressive towards high-performance songs than low-performance songs [Illes et al, 2006;Sewall et al, 2010;DuBois et al, 2011;Moseley et al, 2013;Lyons, 2016].…”