Dietary lipids reduce the expression of carotenoid-based coloration in Lacerta vivipara

Abstract

Summary1. The importance of dietary lipids for carotenoid-based ornaments has rarely been investigated, although theory predicts that dietary lipids may control the development of these widespread animal signals. Dietary lipids have been suggested to enhance the expression of male carotenoidbased ornaments because they provide carotenoids with a hydrophobic domain that facilitates their absorption and transport. Dietary lipids may also enhance the uptake of tocopherols (vitamin E), which share common absorption and transport routes with carotenoids. Here, we test whether dietary lipids enhance carotenoid availability and male carotenoid-based colorations. We also explore the effects of dietary lipids on plasma tocopherol concentration, which allow disentangling between different pathways that may explain how dietary lipids affect ornamental expression. 2. Following a two-factorial design, we manipulated dietary access of naturally occurring fatty acids (oleic acid) and carotenoids (lutein and zeaxanthin) and measured its effects on the circulating concentrations of carotenoids (lutein and zeaxanthin) and vitamin E (a-and c-(b-) tocopherols) and on the ventral, carotenoid-based coloration of male common lizards (Lacerta vivipara). 3. Lutein but not zeaxanthin plasma concentrations increased with carotenoid supplementation, which, however, did not affect coloration. Lipid intake negatively affected circulating concentrations of lutein and c-(b-) tocopherol and led to significantly less orange colorations. The path analysis suggests that a relationship between the observed colour change and the change in plasma concentrations of c-(b-) tocopherol may exist. 4. Our study shows for the first time that dietary lipids do not enhance but reduce the intensity of male carotenoid-based ornaments. Although dietary lipids affected plasma carotenoid concentration, its negative effect on coloration appeared to be linked to lower vitamin E plasma concentrations. These findings suggest that a conflict between dietary lipids and carotenoid and tocopherol uptake may arise if these nutrients are independently obtained from natural diets and that such conflict may reinforce signal honesty in carotenoid-based ornaments. They also suggest that, at least in the common lizard, sexual selection with respect to carotenoid-based coloration may select for males with low antioxidant capacity and thus for males of superior health.

Corticosterone regulates multiple colour traits in Lacerta [Zootoca] vivipara males

“…As colour change in carotenoid-based coloration of common lizards is mediated by iridophores rather than carotenoids (San-Jose et al, 2013), corticosterone may modulate carotenoid-based coloration via iridophore cell receptors, which would explain why elevated blood corticosterone levels impaired both carotenoid-and melanin-based ventral coloration. On the other hand, corticosterone may indirectly influence carotenoid-and melanin-based coloration by increasing oxidative stress (Costantini et al, 2008(Costantini et al, , 2011, as proposed for male common lizards (Cote et al, 2010;San-Jose et al, 2012b) and demonstrated for other species (Galvan & Alonso-Alvarez, 2008), respectively.…”

“…Given that the prey items used here and in Cote et al. 's study (2010) may have differed in nutritional quality and that the ventral coloration of male common lizards has been shown to vary according to the amount of certain dietary nutrients (San‐Jose et al ., , ), the absence of this effect suggests that the corticosterone effect may be modulated by food quality rather than food quantity. In contrast to Cote et al .…”

“…These findings contrast with studies in birds, which have shown that food availability substantially determines the expression of carotenoid‐based ornaments (Hill, ; McGraw et al ., ). However, in contrast to birds, carotenoid‐based coloration is not affected by carotenoid ingestion in the common lizard, in the brown anole or in the other lizard species studied to date (Olsson et al ., , ; Steffen et al ., ; San‐Jose et al ., ). This suggests that lizard coloration may not be carotenoid‐limited, which could explain why food availability did not affect carotenoid‐based ornaments.…”

“…In July 2008, 36 adult common lizard males were captured at Somport (Central Pyrenees, Huesca, Spain, 42°47′40″ N, 0°31′33″ W, 1634 m above sea level) and housed in the laboratory at the Instituto Pirenaico de Ecología (Jaca, Huesca, Spain). Lizards were individually housed in terraria equipped with two shelters, a water pond and peat soil as substrate (for further details see San‐Jose et al ., ) and were fed with a wax moth larva ( Galleria mellonella ) every 4 days and provided with water ad libitum . Half of the lizards were randomly assigned to a corticosterone treatment group and the other half to a control group.…”

Frequency-dependent sexual selection with respect to progeny survival is consistent with predictions from rock-paper-scissors dynamics in the European common lizard

“…In contrast, iridophores exhibit condition-dependency and account for phenotypic plasticity (San-Jose et al, 2013; see also . The male's ventral coloration exhibits color morphs and is at the same time condition-dependent Fitze et al, 2009;San-Jose et al, 2012b), i.e., phenotypically plastic. O alleles positively and negatively affect endurance and survival, respectively .…”