Sperm of colourful males are better protected against oxidative stress

Abstract

Sperm cells are highly vulnerable to free radicals, and sperm quality and male fertility are critically affected by oxidative stress. Recently, sexual ornaments, particularly carotenoid-based colourful traits, have been proposed to depend on a male's capacity to resist oxidative stress, and thus to signal sperm quality. We conducted an experimental test of this hypothesis on great tits Parus major, in which adults are sexually dichromatic in carotenoid-based breast plumage. We report the first evidence that ornaments and sperm quality may be linked through oxidative stress. When experimentally subjected to oxidative stress resulting from increased workload, less colourful males suffered a greater reduction in sperm motility and swimming ability, and increased levels of sperm lipid peroxidation compared to more colourful males. Moreover, the level of sperm lipid peroxidation was negatively correlated with sperm quality. Finally, carotenoid supplementation increased sperm quality of less colourful males, suggesting that pale males are deficient in carotenoid antioxidants.

Inbreeding depression of sperm traits in the zebra finch Taeniopygia guttata

“…In birds, sperm velocity appears to be sensitive to high levels of oxidative stress (Helfenstein et al. 2010); here, we show that it may also be sensitive to genetic stress caused by inbreeding.…”

Lycopene improves the distorted ratio between AA/DHA in the seminal plasma of infertile males and increases the likelihood of successful pregnancy

“…The color of the breast plumage of male great tits is due to carotenoids. Consequently, males with more colorful plumage have increased protection against oxidative stress and have markedly better reproductive ability 23 . In addition to the effect of lycopene treatment on PUFA levels in seminal plasma, we have also found a positive effect on pregnancy rates in couples suffering from idiopatic or male factor infertility.…”

Oxidative stress and condition-dependent sexual signals: more than just seeing red

“…For example, both the percentage of motile sperm and sperm swimming ability can correlate negatively with oxidative stress [78,79], suggesting that oxidative stress may influence the functional characteristics of sperm. Various oxidative insults incurred along the female genital tract could also mean that only individual sperm free from oxidative stress and possessing good antioxidant protection will be able to reach the ovum [77].…”