Data from: A significant component of ageing (DNA damage) is reflected in fading breeding colors: an experimental test using innate antioxidant mimetics in painted dragon lizards

A decade ahead of their time, von Schantz and coworkers united sexual selection and free radical biology by identifying causal links between deep-rooted physiological processes that dictate resistance to toxic waste from oxidative metabolism (reactive oxygen species), and phenotypic traits, such as ornaments. Ten years later, these ideas have still only been tested with indirect estimates of free radical levels (oxidative stress) subsequent to the action of innate and dietary antioxidants. Here we measure net superoxide (a selection pressure for antioxidant production) and experimentally manipulate superoxide antioxidation using a synthetic mimetic of superoxide dismutase, Eukarion 134 (EUK). We then measure the toxic effect of superoxide in terms of DNA erosion and concomitant loss of male breeding coloration in the lizard, Ctenophorus pictus. Control males suffered more DNA damage than EUK-males. Spectroradiometry showed that male coloration is lost in relation to superoxide and covaries with DNA erosion; in control males these variables explained 72 % of color loss, whereas in EUK males, the fading of coloration was unaffected by superoxide and unrelated to DNA damage. Thus, EUK’s powerful antioxidation removes the erosion effect of superoxide on coloration and experimentally verifies the prediction that colors reflect innate capacity for antioxidation.

该研究比学界前沿超前十年，von Schantz及其团队通过揭示调控氧化代谢所产生的毒性废物——活性氧（reactive oxygen species）——抗性的深层生理过程，与装饰性表型等性状之间的因果关联，将性选择（sexual selection）与自由基生物学（free radical biology）两大研究领域相统一。十年后的今日，相关假说仍仅通过对先天与膳食抗氧化剂发挥作用后自由基水平（氧化应激（oxidative stress））的间接估算得以验证。
本研究通过合成超氧化物歧化酶（superoxide dismutase）模拟剂Eukarion 134（EUK），对超氧阴离子（superoxide）的抗氧化过程实施实验干预，并直接测定净超氧阴离子水平（超氧阴离子是驱动抗氧化物质生成的选择压力）。随后，我们以饰纹岩蜥（Ctenophorus pictus）为实验对象，从DNA损伤与雄性繁殖色彩消退两个维度，评估超氧阴离子的毒性效应。
结果显示，对照组雄性个体的DNA损伤程度显著高于EUK处理组雄性。光谱辐射测量表明，雄性色彩消退与超氧阴离子水平相关，且与DNA损伤程度呈共变关系：对照组雄性的色彩消退程度有72%可由这两个变量解释；而EUK处理组雄性的色彩消退则不受超氧阴离子影响，且与DNA损伤无关联。
综上，EUK的强效抗氧化作用消除了超氧阴离子对色彩的损伤效应，实验验证了“雄性色彩可反映个体先天抗氧化能力”这一核心预测。