Sex-specific SOD levels and DNA damage in painted dragon lizards (Ctenophorus pictus)

When groups of individuals differ in activities that may influence the production of reactive molecules, such as superoxide, we expect selection to result in congruent upregulation of antioxidant production in the group(s) most at risk of suffering concomitant erosion of essential tissue and biomolecules, such as DNA. We investigate this in a (near) annual lizard species, the Australian painted dragon (Ctenophorus pictus), in which males and females have fundamentally different lifestyles, with males being overtly conspicuous and aggressive, whereas females are placid and camouflaged. When kept in identical conditions to females in captivity, males had higher levels of superoxide dismutase (SOD) through the activity season, which is consistent with selection for a higher capacity of superoxide antioxidation and a lower level of DNA damage than females. Males, however, lacked the clear negative, linear relationship between SOD and DNA erosion observed in females, suggesting that female upregulation of SOD results in a more predictable antioxidation and a more immediate target for selection. Lastly, we analysed aspects of female reproduction from a DNA erosion perspective. Females closer to ovulation, hence with less remaining, circulating vitellogenin, had higher superoxide levels. Furthermore, a multiple regression analysis showed that females that produced more clutches over time suffered more DNA erosion, whereas females with higher SOD levels suffered less DNA erosion.