Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity

Abstract

Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism.

Dynamic sexual dichromatism produces a sex signal in an explosively breeding Neotropical toad: A model presentation experiment

“…Bell and Zamudio, 2012;Doucet and Mennill, 2010;Maan and Cummings, 2009;Ries et al, 2008). Sexual dichromatism is relatively rare in anurans, having been documented in only 2% of species (Bell and Zamudio, 2012). Bell and Zamudio (2012) distinguish two classes of sexual dichromatism in anurans: ontogenetic dichromatism and dynamic dichromatism.…”

“…Sexual dichromatism has recently garnered attention in anurans (e.g. Bell and Zamudio, 2012;Doucet and Mennill, 2010;Maan and Cummings, 2009;Ries et al, 2008). Sexual dichromatism is relatively rare in anurans, having been documented in only 2% of species (Bell and Zamudio, 2012).…”

Observations on the Calling Behaviour of the Jervis Bay Tree FrogLitoria jervisiensis

“…Dynamic sexual dichromatism is a temporary colour change that occurs in male frogs during the breeding period (Bell and Zamudio 2012). This phenomenon has been recorded in the stream-breeding hylids Litoria jungguy, L. lesueuri, L. wilcoxi (Donnellan & Mahony 2004;Kriger & Hero 2007) and L. revelata (Webster 2013).…”

“…al. 2012); or the bright colour being evidence of the fitness of the male frog (Bell and Zamudio 2012). L. jervisiensis closely resembles L. revelata and some authors have placed these frogs in a distinct species-group (Barker et.…”

Do Masculine Men Smell Better? An Association Between Skin Color Masculinity and Female Preferences for Body Odor

“…Sexual dichromatism is frequent between species of birds (Bortolotti et al 1996;Dale et al 2015), amphibians (Bell and Zamudio 2012) and fish (Kodric-Brown 1998). Human skin color, apart from being an important indicator of current health (Fink et al 2012;Re et al 2011;Stephen et al 2009b;Whitehead et al 2012), has been shown to be different between human females and males (Van den Berghe and Frost 1986) but also to be considered attractive in mate preferences (Carrito et al 2016).…”