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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.

SUBMITTER: Costantini D

PROVIDER: S-EPMC5809033 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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

Costantini David D

Current zoology 20170201 1

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 p ...[more]

PMID: 29492033

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Project description:BackgroundMany of the 35 million women and girls aged 15-49 requiring humanitarian assistance have inadequate access to the sexual and reproductive health (SRH) services to which they are entitled. Ensuring accountability is critical to realizing their SRH and reproductive rights (RR).ObjectivesThis scoping review examines the extent and nature of existing evidence on accountability strategies for SRH in humanitarian settings in different geographical scopes/contexts, and contextualizes these findings in the larger thematic literature. This review seeks to answer the following questions: What accountability strategies are employed to address the availability, accessibility, acceptability, and quality of SRH in humanitarian settings? What do we know about the successes and challenges of the given strategies? What are the implications for practice?MethodsWe consulted public health, social science, and legal databases including SCOPUS, PubMed, ProQuest, and LexisNexis for peer-reviewed articles, as well as Google Advanced search for grey literature; the search was conducted in March 2019. We searched for relevant articles and documents relating to accountability, humanitarian, and SRH and/or RR. To identify key challenges not reflected in the literature and additional grey literature, 18 key informants from international NGOs, local government bodies, academia, and donor agencies were interviewed from March-June 2019.ResultsA total of 209 papers and documents were identified via our literature searches and interviews for review. We identified three categories of approaches to accountability in our background reading, and we then applied these to the papers reviewed a priori. We created a fourth category based on our findings. The categories include: (1) humanitarian principles, codes of conduct, and legal instruments; (2) technical, performance, and impact standards; (3) efforts to solicit and address the rights and needs of the affected populations, or "listening and responding," and, (4) accountability demands made by affected populations themselves. Almost all papers identified referred to challenges to realizing accountability in humanitarian contexts. There are promising accountability approaches - some specific to SRH and some not - such as open-ended feedback from affected populations, quality improvement, and practical application of standards. Reflecting a largely top down orientation, papers concentrate on accountability mechanisms within humanitarian work, with much less focus on supporting affected populations to deepen their understanding of structural causes of their position, understand their entitlements, or access justice.ConclusionIn the last 20 years, there has been increasing standard and guideline development and program experiences related to accountability in humanitarian settings. Yet, the emphasis is on tools or mechanisms for accountability with less attention to changing norms regarding SRH and RR within affected communities, and to a lesser extent, among implementers of humanitarian programs or to institutionalizing community participation.

Project description:Inferring from patterns observed in biomedical research, ecoimmunological theory predicts that oxidative stress is a ubiquitous physiological cost that contributes to generating variation in immune function between individuals or species. This prediction is, however, often challenged by empirical studies testing the relationship between immune response or infection and oxidative status markers. This points out the importance of combining ecological immunology and oxidative stress ecology to further our understanding of the proximate causes and fitness consequences of individual variation in health, and adaptability to natural and anthropogenic environmental changes. I reviewed evidence and performed phylogenetic meta-analyses of changes in oxidative status markers owing to either injection of an antigen or infection in captive and free-living vertebrates (141 studies, 1262 effect sizes, 97 species). The dataset was dominated by studies on fish, birds and mammals, which provided 95.8% of effect sizes. Both antigen injection and parasite exposure were associated with changes of oxidative status. There were significant effects of taxonomic class and experimental environment (captivity vs. wild). In contrast with my predictions, age category (young vs. adult), study design (correlational vs. experimental) and proxies of pace of life (clutch size, litter size, and body mass; for birds and mammals only) were negligible in this dataset. Several methodological aspects (type of immunostimulant, laboratory assay, tissue analysed) showed significant effects on both strength and direction of effect. My results suggest that alterations of oxidative status are a widespread consequence of immune function across vertebrates. However, this work also identified heterogeneity in strength and direction of effect sizes, which suggests that immune function does not necessarily result in oxidative stress. Finally, this work identifies methodological caveats that might be relevant for the interpretation and comparability of results and for the application in conservation programs.

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

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

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