Parasites and health affect multiple sexual signals in male common wall lizards, Podarcis muralis

Abstract

Multiple advertising sexual traits may either advertise different characteristics of male condition or be redundant to reinforce reliability of signals. Research has focused on multiple visual traits. However, in animals that use different multiple additional sensory systems, such as chemoreception, different types of traits might have evolved to signal similar characteristics of a male quality using different sensory channels. We examined whether ventral coloration and chemicals in femoral gland secretions of male common wall lizards, Podarcis muralis, are affected by their health state (blood-parasite load and cell-mediated immune response). Our results indicated that less parasitized lizards had brighter and more yellowish ventral colorations and also femoral secretions with higher proportions of two esters of octadecenoic acid. In addition, lizards with a greater immune response had more saturated coloration and secretions with higher proportions of octadecenoic acid methyl ester. We suggest that these signals would be reliable because only healthier males seemed able to allocate more carotenoids to coloration and presumably costly chemicals to secretions. The use of multiple sensory channels may provide more opportunities to signal a male quality under different circumstances, but also may reinforce the reliability of the signal when both types of traits may be perceived simultaneously.

Chemical communication, sexual selection, and introgression in wall lizards

“…The lipophilic chemical composition of the femoral secretions (Table S2) was consistent with that previously reported for this species (Martín and López 2006b;Martín et al 2008;Pellitteri-Rosa et al 2014). Considering those 21 compounds selected from the samples on the basis of their common occurrence (Table 1), the lizard secretions consisted primarily of steroids (85.7%), but also contained waxy esters (3.7%), tocopherols (7.6%), terpenoids (2.1%), alkenes (0.7%), and ketones (0.3%).…”

“…These secretions are chemically complex and their composition may mediate social interactions, territoriality, and reproduction (e.g., López and Martín 2002;Carazo et al 2007), and ultimately play a key role in determining mating success (Mayerl et al 2015). In lacertid lizards, for example, the proportions of cholesterol and campesterol have been shown to correlate positively with body size (López et al 2006;Martín and López 2007), and higher proportions of cholesta-5,7-dien-3-ol, ergosterol and waxy esters have been associated with lower parasite loads and higher immune responses (López et al 2006;Martín et al 2008). In lacertid lizards, for example, the proportions of cholesterol and campesterol have been shown to correlate positively with body size (López et al 2006;Martín and López 2007), and higher proportions of cholesta-5,7-dien-3-ol, ergosterol and waxy esters have been associated with lower parasite loads and higher immune responses (López et al 2006;Martín et al 2008).…”

Common Wall Lizard Females (Podarcis muralis) do not Actively Choose Males Based on their Colour Morph

“…In P. muralis , the effects of parasite load and immunocompetence on the relative proportions of lipophilic chemical compounds in femoral gland secretions have been demonstrated (Martin et al. ), as well as differences in some compounds (especially tocopherols and furanones) among morphs (Pellitteri‐Rosa et al. ).…”

Blood parasites in two co-existing species of lizards (Zootoca vivipara and Lacerta agilis)

“…Reports have documented that haemogregarinid parasites influenced several life-history traits, such as body mass condition (Amo et al 2004), age-dependant host mortality (Sorci 1996), colour, composition of femoral secretions (Martin et al 2008), and reduction of tail regeneration after autotomy (Oppliger and Clobert 1997).…”