Antioxidant Defenses Predict Long-Term Survival in a Passerine Bird (original) (raw)
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Animal Behaviour, 2008
The expression of most life history traits, such as immunity, growth and the development of sexual signals, is negatively affected by high levels of oxidative stress. Dietary antioxidants can reduce oxidative stress and have therefore been the focus of numerous studies in behavioural and evolutionary ecology in the last few decades. Most of this research has focused on carotenoids, neglecting a number of more common, more potent, and thereby potentially more important, antioxidants, such as polyphenolic antioxidants. However, the effects of several classes of antioxidants on different life history traits have been thoroughly investigated in medical and animal-breeding studies. We suggest that behavioural and evolutionary studies will benefit from incorporating these advances. By reviewing the literature on the effects of antioxidants on life history traits in fish, birds and mammals, we develop a broad framework for dietary antioxidants. Fundamental properties of antioxidants, in particular their biochemistry, their potency and the interactions between them affect their relative relevance for life history traits. Based on tissue affinity, we distinguish between two categories of dietary antioxidants: focal antioxidants that are intrinsically important for a given trait and nonfocal antioxidants that influence traits only indirectly. Furthermore, we show how temporal and spatial environmental variability in antioxidant availability, as well as individual variation in food selection, may generate interindividual differences in the expression of life history traits. Finally, we suggest future research lines and experimental designs that may provide basic information needed to advance our knowledge of the ecological and evolutionary relevance of dietary antioxidants.
Ecology Letters, 2009
The concept of trade-offs is central to our understanding of life-history evolution. The underlying mechanisms, however, have been little studied. Oxidative stress results from a mismatch between the production of damaging reactive oxygen species (ROS) and the organismÕs capacity to mitigate their damaging effects. Managing oxidative stress is likely to be a major determinant of life histories, as virtually all activities generate ROS. There is a recent burgeoning of interest in how oxidative stress is related to different components of animal performance. The emphasis to date has been on immediate or short-term effects, but there is an increasing realization that oxidative stress will influence life histories over longer time scales. The concept of oxidative stress is currently used somewhat loosely by many ecologists, and the erroneous assumption often made that dietary antioxidants are necessarily the major line of defence against ROS-induced damage. We summarize current knowledge on how oxidative stress occurs and the different methods for measuring it, and highlight where ecologists can be too simplistic in their approach. We critically review the potential role of oxidative stress in mediating life-history trade-offs, and present a framework for formulating appropriate hypotheses and guiding experimental design. We indicate throughout potentially fruitful areas for further research.
Journal of Avian Biology, 2014
Oxidative stress has been suggested as a mediator in life-history trade-off . By spending more resources on for example reproduction an organism might sacrifi ce its antioxidant defence. So far, most conclusions on trade-off s between lifehistory traits and oxidative stress have been drawn from laboratory studies using a few model species and there is a need for studies conducted in natural settings. We investigated associations between markers for antioxidant status (antioxidant enzyme activities and antioxidant levels), body condition, age and reproduction in three species of wild-living passerines. Th e impact from an anthropogenic stressor (metal pollution) was also assessed. Th e three bird species showed interspecifi c variation in their SOD and CAT activities, indicating diff erent pathways to eliminate radicals. Th e age of females aff ected both antioxidant status and the breeding performance, indicating the importance of age as a factor in life-history studies. Old birds had lower levels of antioxidants/antioxidant enzyme activities and they produced larger broods/more successful broods, though the latter might be confounded by surviving females having increased fi tness. Metal exposure had a negative impact on breeding, and improved breeding outcome was also associated with increased antioxidant defence, but metal exposure was not directly related to the oxidative status of birds, emphasizing that additional stressors might independently aff ect the same traits. Our results highlight that caution has to be taken when generalizing and extrapolating results to even closely related species. Th e results support the idea that there is a cost of reproduction, in terms of increased resources spent on antioxidant defence, though this should be confi rmed with experimental studies.
Oikos, 2009
Selection on physiological traits is thought to mediate the evolution of individual life-history parameters like reproduction, longevity, and the tradeoffs between them, but almost nothing is known about the relationships between physiological and life-history parameters in the wild. Antioxidants are strong candidates to correlate with life histories because they play a critical role in preventing free radical damage to macromolecules, and many types are involved in sexual signaling and embryo provisioning. Here for the first time we present data on associations between serum antioxidant measures (antioxidant capacity and concentrations of uric acid, vitamin E and carotenoids) and indices of reproductive rate and age in two bird species. After controlling for age, 36% of the variation in hatching rate in Leach's storm-petrels Oceanodroma leucorhoa was accounted for by a negative association with antioxidant capacity. Age was negatively associated with uric acid levels. Savannah sparrows Passerculus sandwichensis showed no association between antioxidant capacity and fledging rate, but serum b-carotene levels were weakly positively associated with fledging rate. Because antioxidant levels are known to vary markedly within individuals over time, detection of associations between long-term measures of reproduction and instantaneous antioxidant levels suggests strong (though not necessarily causal) relationships. Relationships between antioxidants and life histories appeared to differ in sparrows and storm-petrels though, likely due to variation in diet, ecology, and life-history evolution in these distantly related species.
Oxidative stress in ecology and evolution: lessons from avian studies
Ecology Letters, 2008
Although oxidative stress is a central topic in biochemical and medical research, the number of reports on its relevance in life-history studies of non-human animals is still low. Information about oxidative stress in wild birds may help describe functional interactions among the components of life-history traits. Currently available evidence suggests that oxidative stress may impart an important physiological cost on longevity, reproduction, immune response or intense physical activity. Given the gaps in our present knowledge, it is still premature to attempt to draw definitive conclusions and basic questions (e.g. how is oxidative stress generated and how do organisms cope with it?) have yet to be fully explored under natural conditions. Therefore, caution is needed in developing hypotheses or drawing general conclusions until additional data become available to perform more rigorous comparative analyses.
Journal of Comparative Physiology B, 2012
Antioxidants have a large potential to coevolve with life-histories because of their capacity to counteract the negative eVects of free radicals on Wtness. However, only a few studies have explored the association between antioxidant levels and life-history strategies comparing a large number of species. Here we used an extensive dataset of 125 species of birds to investigate the association between concentrations of antioxidants (carotenoids and vitamin E) in the liver, which is the main storage organ for fat-soluble antioxidants, and life-history and morphology. We found that high liver antioxidant concentrations were associated with life-history strategies characterized by "live slow, die old", in clear contrast to previous studies reporting a relationship between high plasma antioxidants and life-histories characterized by "live fast, die young". Thus, high carotenoid concentrations were present in species with large body, brain and egg sizes, high absolute metabolic rate and a resident lifestyle, while high vitamin E concentrations were present in species with large brain size and long life span and incubation period. Our results indicate that antioxidants and life-histories coevolve, and that this may be mediated by positive Wtness consequences of the accumulation of liver antioxidants, as species with higher antioxidant levels live longer.
Life history correlates of oxidative damage in a free-living mammal population
Functional Ecology, 2009
Reactive oxygen species, produced as a by-product of normal metabolism, can cause intracellular damage and negatively impact on cell function. Such oxidative damage has been proposed as an evolutionarily important cost of growth and reproduction and as a mechanistic explanation for organismal senescence, although few tests of these ideas have occurred outside the laboratory.
The Challenges of Integrating Oxidative Stress into Life-history Biology
BioScience, 2011
It has been proposed that the molecular and physiological systems that regulate biological functions impose costs and constraints that are fundamental to the understanding of variation in life histories. In particular, studies of oxidative stress emphasize how evolutionary contingency can impose novel trade-offs for organisms, and how this may create or eliminate functional linkages between traits. Here, we critically assess the conceptual and empirical basis for these claims and what they mean for the study of life-history variation. Two key challenges are to go beyond the current focus on single components of regulatory systems, assessed at single points in time, and to establish the importance of trait-and stagespecific nutrient requirements for the functional linkage between life-history traits. Furthermore, future progress will critically depend on the replication of laboratory studies in natural settings to target the complexity of trade-off regulation in the wild.