Socially selected ornaments influence hormone titers of signalers and receivers

Abstract

Decades of behavioral endocrinology research have shown that hormones and behavior have a bidirectional relationship; hormones both influence and respond to social behavior. In contrast, hormones are often thought to have a unidirectional relationship with ornaments. Hormones influence ornament development, but little empirical work has tested how ornaments influence hormones throughout life. Here, we experimentally alter a visual signal of fighting ability in Polistes dominulus paper wasps and measure the behavioral and hormonal consequences of signal alteration in signalers and receivers. We find wasps that signal inaccurately high fighting ability receive more aggression than controls and receiving aggression reduces juvenile hormone (JH) titers. As a result, immediately after contests, inaccurate signalers have lower JH titers than controls. Ornaments also directly influence rival JH titers. Three hours after contests, wasps who interacted with rivals signaling high fighting ability have higher JH titers than wasps who interacted with rivals signaling low fighting ability. Therefore, ornaments influence hormone titers of both signalers and receivers. We demonstrate that relationships between hormones and ornaments are flexible and bidirectional rather than static and unidirectional. Dynamic relationships among ornaments, behavior, and physiology may be an important, but overlooked factor in the evolution of honest communication.honesty | challenge hypothesis | androgens | communication | social costs T he prevailing view in communication research is that hormones, such as androgens, influence the expression of ornaments and also function as "physiological costs" that maintain signal accuracy over evolutionary time (1). For example, the immunocompetence handicap hypothesis proposes that high androgen titers are required for animals to develop elaborate ornaments and high androgen titers also impose immune-related costs (2, 3). As a result, only the best individuals can afford to produce elaborate ornaments.There is growing evidence that the unidirectional view of hormone/ornament relationships is incomplete (4, 5). Instead, relationships between hormones and ornaments may be bidirectional and therefore more complex than previously anticipated. Although there is little experimental evidence that ornaments influence hormone titers, theory suggests ornaments could affect the hormone titers of individuals displaying ornaments (signalers) and/or individuals perceiving ornaments (receivers) directly or indirectly via behavior.Understanding how ornaments influence hormone titers of signalers and receivers is important because hormones have persistent effects on morphology, physiology, and behavior. Androgens in vertebrates and juvenile hormone (JH) in insects mediate the fecundity vs. lifespan tradeoff (6, 7). High titers of androgens and JH typically increase success in competitive contexts, but also decrease survival (8, 9). Therefore, if ornaments alter hormones, the hormonal changes will produce a cascade of sub...

Achromatic plumage brightness predicts stress resilience and social interactions in tree swallows (Tachycineta bicolor)

“…However, signals themselves can alter the social environment that an animal experiences by changing the frequency and nature of social interactions, which may be costly (Møller 1987;Dey et al 2014;Webster et al 2017). Furthermore, social experiences can result in physiological changes that ultimately influence the production and maintenance of signals (Dey et al 2014); thus, there is the potential for dynamic feedback between physiology, signals, and the social environment (Vitousek et al 2013;Levin et al 2016;Tibbetts et al 2016; Crocker-Buta and Leary 2018; Levin et al 2018). Under this scenario, mechanisms that link physiology, signals, and the ability to withstand challenges have the potential to generate the integrated suites of traits associated with honest signaling.…”

Information‐gathering as a response to manipulated signals in the eastern fence lizard, Sceloporus undulatus

“…In spiny‐footed lizards, adult aggression was reduced toward juveniles with experimentally manipulated red coloration (Fresnillo, Belliure, & Cuervo, ). Experimentally painted wasps received more aggression, which changed juvenile hormone levels of both signalers and receivers (Tibbetts, Crocker, & Huang, ). Here, using territorial Sceloporus undulatus lizards in the wild, we examine receiver response to intruders with different patch sizes to determine (a) if patch size conveys information assessed during male‐male interactions and (b) if/how receivers modulate their behavioral responses to different types of signals.…”

“…In spiny-footed lizards, adult aggression was reduced toward juveniles with experimentally manipulated red coloration (Fresnillo, Belliure, & Cuervo, 2015). Experimentally painted wasps received more aggression, which changed juvenile hormone levels of both signalers and receivers (Tibbetts, Crocker, & Huang, 2016).…”

Plumage manipulation alters the integration of social behavior, physiology, internal microbiome, and fitness

“…This finding suggests that dynamic feedback may play an important role in coordinating an integrated signaling phenotype. Our results have implications for understanding how variation in signal expression arises and is maintained and the extent to which the information encoded in signals is contingent upon their use in a social environment.Keywords: social feedback; phenotypic integration; plumage signals Tibbetts et al 2016;Vitousek et al 2013). While both classic honesty mechanisms and dynamic feedback might produce similarly coordinated signaling phenotypes, the underlying processes are quite different (Rubenstein & Hauber 2008;Tibbetts 2014;Vitousek et al 2014).…”

“…Keywords: social feedback; phenotypic integration; plumage signals Tibbetts et al 2016;Vitousek et al 2013). While both classic honesty mechanisms and dynamic feedback might produce similarly coordinated signaling phenotypes, the underlying processes are quite different (Rubenstein & Hauber 2008;Tibbetts 2014;Vitousek et al 2014).…”