The Cellular Basis of Polymorphic Coloration in Common Side-Blotched Lizards,Uta stansburiana

Abstract

Diurnal lizards are useful model organisms for the study of color polymorphisms. The cellular basis of nonavian reptilian coloration and dermal chromatophores, as well as the different pigments contained therein, is relatively well understood. Nonetheless, specific predictions cannot be made for the biochemical chromatophore constituents of individual species a priori. Despite well-documented associations between throat coloration and behavioral, physiological, and life history traits, the cellular basis of throat coloration in polymorphic Common Side-Blotched Lizards, Uta stansburiana, has never been studied. We used a combination of chromatographic techniques in conjunction with transmission electron microscopy and a thin-layer reflectance model to determine the cellular basis of polymorphic coloration in U. stansburiana. We found that different morphs express coloration through varying spatial arrangements of dietary xanthophylls (lutein and zeaxanthin), differential synthesis of drosopterins, differential melanin synthesis, and morph-specific iridophore reflecting platelets. Our results indicate that chromatic variations in this polymorphism cannot be attributed to alternative xanthophore pigmentation or structural reflectance alone. Instead, the chromatophores of U. stansburiana are multicomponent color signals.

Body coloration and mechanisms of colour production in Archelosauria: The case of deirocheline turtles

“…Previous reports have described iridophores with randomly organized platelets in red and white skin of Phelsuma grandis where they produce broadband reflection [16]. In contrast, reflecting platelets in orange and yellow skin regions of Uta stansburiana [57], Sceloporus undulatus , and S. magister [56] are highly organized to reflect orange and yellow wavelengths. Even though broadband reflecting iridophores do not influence perceived colour, they may increase the brightness of colour regions and their overall conspicuousness to observers [3,103].…”

“…4, 5). Unlike lizards [16,57,97] turtles lack a layer of dermal melanophores in the red-yellow skin regions. Turtles bask to thermoregulate and overheating may represent an immediate risk for them [129], but basking could also have a social function [130] for which it may be advantageous to accumulate heat at a slower rate.…”

“…Based on the length of the minor axis of both intact platelets and empty holes we calculated putative reflective wavelengths of reflecting platelets following equation (2) in Morrison [56] as applied by Haisten et al [57] with refractive index of reflecting platelets 1.83 [58]. However, this model of colour production applies only to reflecting platelets that produce colour through thin-film interference [59], which is characterized by reflecting platelets organized in planes perpendicular to the direction of propagation of incoming light (i.e.…”

Manipulation of parasite load induces significant changes in the structural-based throat color of male iberian green lizards

“…In this sense, the costs of production or maintenance (i.e., honesty) of carotenoid-based ornaments have been studied in different organisms (in lizards, Fitze et al 2009 ; in birds, Mougeot et al 2009 ; in lizards, Cote et al 2010 ; in birds, Simons et al 2012 ). In addition to carotenoid-based ornaments, some yellow or orange-based coloration of lizards (especially American species) are instead based on pterins ( Weiss et al 2012 ; Haisten et al 2015 ). Thus, yellow ornaments based on pterines might be costly to produce because they are synthetized consuming purines via salvage pathways ( Morrison et al 1995 ; Weiss et al 2012 ).…”

“…Melanophores play a key role in the contribution to the blue and UV-blue colorations ( Cox et al 2005 , 2008 ). In contrast, pigment-based colorations present a superficial layer of xantophores/erythrophores that can contain a combination of pigments (pterines and/or carotenoids) ( Kopena et al 2013 ; Olsson et al 2013 ; Haisten et al 2015 ) and that in combination with the remaining skin layers results in yellow, orange, or some red ornaments ( Grether et al 2004 ; San-Jose et al 2013 ). Experimental studies demonstrated the influence of hormones on the structural component ( San-Jose et al 2013 ) and the pigmentary component underlying the coloration of lizards ( Cox et al 2008 ; Cote et al 2010 ).…”