Meta-analysis reveals that reproductive strategies are associated with sexual differences in oxidative balance across vertebrates

Abstract

Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identify which factors are associated with such differences. The dataset included 732 effect size estimates from 100 articles (82 species). Larger unsigned effect size (meaning larger sexual differences in a given marker) occurred in: reptiles and fish; those species that do not provide parental care; and oviparous species. Estimates of signed effect size (positive values meaning higher oxidative stress in males) indicated that females were less resistant to oxidative stress than males in: reptiles while males and females were similar in fish, birds, and mammals; those species that do not provide parental care; and oviparous species. There was no evidence for a significant sexual differentiation in oxidative balance in fish, birds, and mammals. Effect size was not associated with: the number of offspring; whether the experimental animals were reproducing or not; biomarker (oxidative damage, non-enzymatic, or enzymatic antioxidant), the species body mass; the strain (wild vs. domestic); or the study environment (wild vs. captivity). Oxidative stress tended to be higher in females than males across most of the tissues analyzed. Levels of residual heterogeneity were high in all models tested. The findings of this meta-analysis indicate that diversification of reproductive strategies might be associated with sexual differences in oxidative balance. This explorative meta-analysis offers a starting platform for future research to investigate the relationship between sex and oxidative balance further.

Water availability and temperature induce changes in oxidative status during pregnancy in a viviparous lizard

“…We found that pregnant female lizards had higher non‐enzymatic antioxidant capacity than males and experienced higher changes in oxidative status when resources are scarce. A common pattern in oviparous reptiles is for breeding females to exhibit higher sensitivity than male reptiles (Costantini, ). Here, we provided evidence that a viviparous species may also experience a potential extra‐cost of reproduction in females (Costantini, ).…”

“…A common pattern in oviparous reptiles is for breeding females to exhibit higher sensitivity than male reptiles (Costantini, ). Here, we provided evidence that a viviparous species may also experience a potential extra‐cost of reproduction in females (Costantini, ). In Z. vivipara , all adult females ovulate during reproductive season and invest in egg production even in the absence of mating opportunity (Bleu, Le Galliard, Meylan, Massot, & Fitze, ), so non‐reproductive females were lacking in our study.…”

Physiological costs of infection: herpesvirus replication is linked to blood oxidative stress in equids

“…Prior work did not detect any significant sexual differences in oxidative status markers between herpesvirus-infected males and females in Magnificent frigatebird nestlings 20 . Sexual differences in oxidative status markers are also generally small to moderate in mammals, even if among species variation occurs 38 . We suggest that future studies should look at sex effects in more detail, comparing males and females across different demanding phases of life, where sexes might be faced with tradeoffs of greater or lesser magnitude.…”

Mitochondrial Traits Previously Associated With Species Maximum Lifespan Do Not Correlate With Longevity Across Populations of the Bivalve Arctica islandica

“…Differences in population longevity appear to be independent of sampling effort (see for example Gruber et al, 2015) and, although no precise record of age at maturity from our sites could be found, data from the western Atlantic suggests that it is variable among populations (Thompson et al, 1980) and likely correlated to longevity as it is in different bivalve species (Ridgway et al, 2011). As our understanding of oxidative stress increases, it appears that mitochondrial ROS management is at the center of modulation of life-history traits (such as reproduction and growth, see Costantini, 2018). We then suggest that the divergences in observed MRL among populations should not only be the consequence of detrimental effects of stressful conditions, but could also result from the adjustment of maturation to insure completion of the life cycle in the different environmental conditions experienced by the populations.…”