UV coloration influences spatial dominance but not agonistic behaviors in male wall lizards

Abstract

A bright ultraviolet (UV) component in the coloration of males may signal individual quality and thus determine the outcome of male-male contests. Yet, the role of the UV component of coloration in resolving conflicts is still controversial relative to factors such as residency status and seasonality. Here, we investigated whether a reduction of UV reflectance of lateral blue spots in male wall lizards (Podarcis muralis) interacts with residency status (resident vs. intruder) to influence agonistic behaviors, the outcome of contests, and basking time (a measure of spatial dominance). We performed this experiment during one breeding and one non-breeding season. The UV manipulation did not predict the outcome of contests. During the breeding season, the agonistic behaviors and basking time depended on the residency status of males but not on their UV treatment. During the non-breeding season, experimental factors affected basking time only. For a given male, the time spent basking depended in a complex manner on its residency status, its UV treatment, and those of its rival. UV reflectance of blue spots thus influences the processes of mutual assessment and spatial dominance, but is not a critical determinant of fighting success. Altogether, these results evidence context-dependent effects of the UV reflectance of blue spots on territorial behaviors according to residency status and, potentially, season. They also suggest that UV signaling may be more important than expected for malemale interactions during the non-breeding season.

Relationship between oxidative stress and sexual coloration of lizards depends on thermal habitat

“…Developmental costs could manifest as lower immune response (Martin and Lopez 2009) or susceptibility to parasites (Salvador et al 1996), whereas maintenance costs can increase predation risk (Johnson and Candolin 2017) or aggression from conspecifics (Rick and Bakker 2008b). Among lacertid lizards, the European green lizard (Lacerta viridis), the viviparous lizard (Zootoca vivipara), the wall lizard (Podarcis muralis) and the Iberian green lizard (Lacerta schreiberi) bear UV coloration as a sexual signal (Bajer et al 2012;Martin and Lopez 2009) indicating condition (Martin et al 2013), parasite infection (Molnár et al 2013) and territory size (Molnár et al 2016), influencing mate choice and male-male competition (Bajer et al 2011;Martin and Lopez 2009;Martin et al 2015).…”

Linkages between stratospheric ozone, UV radiation and climate change and their implications for terrestrial ecosystems

“…199 UV-reflectance of lateral blue spots in male lizards has a clear role in male-male interactions, including the processes of mutual assessment. 200 If two males have an equal signal from their UV-reflecting throat patch, their behaviour towards each other is more aggressive. 201 At present, evidence for an ecological role of UV vision in animals is steadily increasing, but detailed information of the functional role of UV-absorbing or reflecting tissues often remains a matter of speculation.…”

Colour patch size and measurement error using reflectance spectrophotometry

“…The UV-blue spots are believed to act as social signals and are sexually dimorphic (i.e. they differ in colour between males and females and are smaller and less numerous in females -P erez i de Lanuza, Carazo & Font 2014;Martin et al 2015). The size of these UV-blue spots can vary from a few mm to less than 0Á5 mm in diameter (personal observation), and are therefore a challenge for the acquisition of reliable spectrophotometric measurements.…”

“…However, many relatively small colour patches may be biologically relevant. This includes some of the most interesting colour patches displayed by insects, arachnids, fish, amphibians or lizards, such as the conspicuous ultraviolet (UV)-blue patches found on some of the outer-ventral scales (OVS) of many lacertid lizards, which probably function as social signals (P erez i de Lanuza, Carazo & Font 2014;Martin et al 2015). In these circumstances, researchers using standard equipment must estimate based on intuition the minimum size of a colour patch that can be reliably measured (S min ), with two major shortcomings.…”