Pterin-based ornamental coloration predicts yolk antioxidant levels in female striped plateau lizards (Sceloporus virgatus)

Abstract

Summary1. Maternal investment in egg quality can have important consequences for offspring fitness. For example, yolk antioxidants can affect embryonic development as well as juvenile and adult phenotype. Thus, females may be selected to advertise their yolk antioxidant deposition to discriminatory males via ornamental signals, perhaps depending on the reproductive costs associated with signal production. 2. Female striped plateau lizards (Sceloporus virgatus) develop pterin-based orange colour patches during the reproductive season that influence male behaviour and that are positively associated with the phenotypic quality of the female and her offspring. Here, we assessed one potential developmental mechanism underlying the relationship between offspring quality and female ornamentation in S. virgatus, by examining the relationship between ornament expression and yolk antioxidant levels. 3. As expected, concentrations of the yolk antioxidants vitamin A, vitamin E and carotenoids (lutein and zeaxanthin) were strongly positively intercorrelated. Eggs from larger clutches had fewer antioxidants than eggs from smaller clutches, suggesting that females may be limited in antioxidant availability or use. Fertilized and unfertilized eggs did not differ in yolk antioxidant levels. 4. The size of a female's ornament was positively related to both the concentration and total amount of yolk antioxidants, and ornament colour was positively related to yolk antioxidant concentration. Thus, in S. virgatus, female ornaments may advertise egg quality. In addition, these data suggest that more ornamented females may produce higher-quality offspring, in part because their eggs contain more antioxidants. As the colour ornament of interest is derived from pterins, not carotenoids, direct resource trade-offs between ornaments and eggs may be eliminated, reducing reproductive costs associated with signalling. 5. This is the first example of a positive relationship between female ornamentation and yolk antioxidants in reptiles and may indicate the general importance of these patterns in oviparous vertebrates.

Lumbar curvature: a previously undiscovered standard of attractiveness

“…This view contrasts with evidence from non-human species that an organism's attractiveness as a mate is linked to traits that help solve adaptive challenges related to survival and reproduction (Norris, 1993;Petrie, 1994;Birkhead & Fletcher, 1995;Stacey, Eileen, Rebecca, & Kevin, 2011). We report independent studies testing the overarching proposal that human standards of attractiveness reflect the output of evolved psychological mechanisms designed to detect fitness-relevant traits (Symons, 1995;Thornhill & Gangestad, 1999;Gangestad & Scheyd, 2005;Sugiyama, 2005;Singh & Singh, 2011).…”

Effect of stress on female-specific ornamentation

“…The affected ornament features are sensitive to circulating CORT levels and are predictive of both female and offspring phenotype (Weiss, 2006;Weiss et al, 2009;Weiss et al, 2011). The ornament's susceptibility to the physiological effects of stress is independent of the interrelationships between CORT and body mass, as well as those between CORT and the sex steroid hormones.…”

“…We measured female ornamentation weekly and focused our analyses on peak ornament expression (Weiss et al, 2009;Weiss et al, 2011). To do so, the right throat patch of each female was photographed weekly along with a small ruler using an Olympus C-5050 ZOOM 5-megapixel digital camera set to macro mode with a Super Bright zoom F1.8 lens (Center Valley, PA, USA) under standardized indoor lighting, and each photo series was separately assessed by three people (E.E.M., S.L.W.…”

“…Females develop orange throat patches during the ovarian cycle, with peak ornament size and color occurring around the time of ovulation (Weiss, 2002). Though all reproductive females express some orange color, the extent of ornamentation at peak expression varies among individuals and that variation may function as an honest signal of female phenotype as well as the quality of her eggs and her future offspring (Weiss, 2006;Weiss et al, 2009;Weiss et al, 2011). If corticosterone mediates the expression of this honest signal, then we predict that females experimentally exposed to stressors will produce smaller and less colorful ornaments relative to control females.…”

Temperature experienced during incubation affects antioxidant capacity but not oxidative damage in hatchling red-eared slider turtles (Trachemys scripta elegans)

“…Additionally, ontogenic studies suggest that maturation of the antioxidant system is not completed until early in adulthood and enzymatic antioxidant activity is often lacking until the very end of embryonic development (Khan and Black, 2003;Barata et al, 2005;Fontagné et al, 2008;Rizzo et al, 2007). Thus, during early development, individuals have reduced defenses against oxidative stress and are potentially reliant on dietary antioxidants available in the yolk, including carotenoids, vitamin E and vitamin A (Thompson et al, 1999;Speake et al, 2001;Surai et al, 2001;Dierenfeld et al, 2002;Weiss et al, 2011).…”