Sexual dichromatism and color diversity in the spiny lava lizard Tropidurus spinulosus using lizard visual modelling

Abstract

Colors are important vehicles for social signals in many taxa. In Squamata, previous studies have linked color characteristics and chromatic diversity to sexual selection and, particularly, species showing male-biased body size dimorphism also showed male-biased dichromatism and color diversity. Sexual dichromatism may occur in body regions used for conspecific communication and it may be expressed at wavelengths, such as ultraviolet, easily perceivable by conspecifics. We tested this prediction in a social lizard model, Tropidurus spinulosus, using spectrophotometry and visual modelling which enable colors to be interpreted as the individuals of the same taxon see them. Our results indicate that sexual dichromatism occurs in the ventral regions and the flanks, which are the body regions involved in sexual displays. Males show greater color diversity, having larger color volumes and more contrasting colors. These findings reinforce the idea that sexual selection towards males is coupled with the evolution of male-biased, diverse, coloration which could act as a signal in social reproductive contexts.

Throat colour polymorphism in relation to sex and body size of the Litter skink,Lankascincus fallax

“…This phenomenon which is known as sexual dichromatism where one sex is distinctly or brightly coloured than the other is widespread in the animal kingdom and is well known from fish (Kingston et al, 2003), lizards (Barry Sinervo & Lively, 1996; M Olsson et al, 2007; Sacchi et al, 2013; James E Paterson & Blouin-demers, 2017) and birds (Burns & Shultz, 2012). One of the most well known underlying causes for sexual dichromatism is female mate preference to certain colour morphs (Stuart-Fox & Ord, 2004; Chen et al, 2012; Rossi et al, 2019). However, L. fallax is not only sexually dichromatic, the males also show throat colour polymorphism.…”

“…Male colour polymorphism is also known to be strongly influenced by sexual selection (Healey et al, 2007; Wellenreuther et al, 2014). Previous studies have shown that females show a higher preference to a particular male colour morph when there are multiple colour morphs among males in the population (Kingston et al, 2003; Stuart-Fox & Ord, 2004; Healey et al, 2007; Rossi et al, 2019). Interestingly, it has also been shown that male throat colour polymorphism is related to habitat selection in tree lizards (J. E. Paterson & Blouin-Demers, 2018).…”

Oviductal fluid counterbalances the negative effect of high temperature on sperm in an ectotherm model

“…body size, as occurs in Tropidurus spinulosus ( López Juri et al, 2020 ). Moreover, trade-offs between colour ornamentation variability ( Rossi et al, 2019 ) and sperm resistance to oxidative stress activated by increased temperature ( Tomášek et al, 2017 ) might also produce variation in sperm velocity.…”

Behavioural plasticity in activity and sexual interactions in a social lizard at high environmental temperatures

“…Study species: Tropidurus spinulosus is a member of the Tropiduridae family, which includes many social lizard species [67]. In particular, in T. spinulosus individuals are often observed in groups on rocky outcrops, interacting with one another [49]. It shows a narrow range of preferred temperatures: selected temperature (Tsel) = 33.7˚C, first quartile of the preferred range (Tset-min) = 32.2 and third quartile of the preferred range (Tset-max) = 35.2 [68].…”

“…Lizards are an interesting model to study social interactions in warming environments [42] because they are ectotherms and exhibit a marked social behaviour and interesting sexual selection dynamics [43,44]. Males may move between perch positions to attract females and repel other males [45][46][47], and may engage in behavioural displays to communicate with conspecifics [48][49][50]. Female and male mate choice has been reported in lizards and is often based on visual phenotypic traits [51][52][53][54].…”