Nestling erythrocyte resistance to oxidative stress predicts fledging success but not local recruitment in a wild bird.
Ontology highlight
ABSTRACT:
SUBMITTER: Losdat S
PROVIDER: S-EPMC3565502 | biostudies-other | 2013 Feb
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Persistent phenotypic changes due to early-life stressors are widely acknowledged, but their relevance for wild, free-living animals is poorly understood. We evaluated effects of two natural stressors experienced when young (maltreatment by adults and nutritional stress) on stress physiology in wild Nazca boobies (Sula granti) 6-8 years later, an exceptionally long interval for such studies. Maltreatment as a nestling, but not nutritional stress, was associated years later with depressed baseline corticosterone in females and elevated stress-induced corticosterone concentration [CORT] in males. These results provide rare evidence of long-term hormonal effects of natural early-life stress, which may be adaptive mechanisms for dealing with future stressors.
| S-EPMC5803595 | biostudies-literature
Project description:The immune system provides vital protection against pathogens, but extensive evidence suggests that mounting immune responses can entail survival and fecundity costs. The physiological mechanisms that underpin these costs remain poorly understood, despite their potentially important role in shaping life-histories. Recent studies involving laboratory models highlight the possibility that oxidative stress could mediate these costs, as immune-activation can increase the production of reactive oxygen species leading to oxidative stress. However, this hypothesis has rarely been tested in free-ranging wild populations, where natural oxidative statuses and compensatory strategies may moderate immune responses and their impacts on oxidative status. Furthermore, the possibility that individuals scale their immune responses according to their oxidative status, conceivably to mitigate such costs, remains virtually unexplored. Here, we experimentally investigate the effects of a phytohaemagglutinin (PHA) immune-challenge on oxidative status in wild male and female white-browed sparrow weavers, Plocepasser mahali. We also establish whether baseline oxidative status prior to challenge predicts the scale of the immune responses. Contrary to previous work on captive animals, our findings suggest that PHA-induced immune-activation does not elicit oxidative stress. Compared with controls (n = 25 birds), PHA-injected birds (n = 27 birds) showed no evidence of a differential change in markers of oxidative damage or enzymatic and non-enzymatic antioxidant protection 24 hours after challenge. We did, however, find that the activity of a key antioxidant enzyme (superoxide dismutase, SOD) prior to immune-activation predicted the scale of the resulting swelling: birds with stronger initial SOD activity subsequently produced smaller swellings. Our findings (i) suggest that wild birds can mount immune responses without suffering from systemic oxidative stress, and (ii) lend support to biomedical evidence that baseline oxidative status can impact the scale of immune responses; a possibility not yet recognised in ecological studies of immunity.
| S-EPMC4376632 | biostudies-literature
Project description:Recent data suggest that, in animals living in social groups, stress-induced changes in behavior have the potential to act as a source of information, so that stressed individuals could themselves act as stressful stimuli for other individuals with whom they interact repeatedly. Such form of cross-over of stress may be beneficial if it enhances adaptive responses to ecological stressors in the shared environment. However, whether stress can be transferred among individuals during early life in natural populations remains unknown. Here we tested the effect of living with stressed siblings in a gull species where, as in many vertebrates, family represents the basic social unit during development. By experimentally modifying the level of stress hormones (corticosterone) in brood mates, we demonstrate that the social transfer of stress level triggers similar stress responses (corticosterone secretion) in brood bystanders. Corticosterone-implanted chicks and their siblings were faster in responding to a potential predator attack than control chicks. In gulls, fast and coordinated reactions to predators may increase the chances of survival of the whole brood, suggesting a beneficial fitness value of cross-over of stress. However, our data also indicate that living with stressed brood mates early in life entails some long-term costs. Near independence, fledglings that grew up with stressed siblings showed reduced body size, high levels of oxidative damage in lipids and proteins, and a fragile juvenile plumage. Overall, our results indicate that stress cross-over occurs in animal populations and may have important fitness consequences.
| S-EPMC5495277 | biostudies-literature
Project description:Habitat conversion for agriculture is a major driver of biodiversity loss, but our understanding of the demographic processes involved remains poor. We typically investigate the impacts of agriculture in isolation even though populations are likely to experience multiple, concurrent changes in the environment (e.g. land and climate change). Drivers of environmental change may interact to affect demography, but the mechanisms have yet to be explored fully in wild populations.Here, we investigate the mechanisms linking agricultural land use with breeding success using long-term data for the formerly Critically Endangered Mauritius kestrel Falco punctatus, a tropical forest specialist that also occupies agricultural habitats. We specifically focused on the relationship between breeding success, agriculture and the timing of breeding because the latter is sensitive to changes in climatic conditions (spring rainfall) and enables us to explore the interactive effects of different (land and climate) drivers of environmental change.Breeding success, measured as egg survival to fledging, declines seasonally in this population, but we found that the rate of this decline became increasingly rapid as the area of agriculture around a nest site increased. If the relationship between breeding success and agriculture was used in isolation to estimate the demographic impact of agriculture, it would significantly under-estimate breeding success in dry (early) springs and over-estimate breeding success in wet (late) springs.Analysis of prey delivered to nests suggests that the relationship between breeding success and agriculture might be due, in part, to spatial variation in the availability of native, arboreal geckos.Synthesis and applications. Agriculture modifies the seasonal decline in breeding success in this population. As springs are becoming wetter in our study area and since the kestrels breed later in wetter springs, the impact of agriculture on breeding success will become worse over time. Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs. Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.
| S-EPMC4279951 | biostudies-literature
Project description:Recent studies of non-social animals have shown that sexually selected traits signal at least one measure of genetic quality: heterozygosity. To determine whether similar cues reveal group quality in more complex social systems, we examined the relationship between territory size, song structure and heterozygosity in the subdesert mesite (Monias benschi), a group-living bird endemic to Madagascar. Using nine polymorphic microsatellite loci, we found that heterozygosity predicted both the size of territories and the structure of songs used to defend them: more heterozygous groups had larger territories, and more heterozygous males used longer, lower-pitched trills in their songs. Heterozygosity was linked to territory size and song structure in males, but not in females, implying that these traits are sexually selected by female choice and/or male-male competition. To our knowledge, this study provides the first direct evidence in any animal that territory size is related to genetic diversity. We also found a positive association between seasonal reproductive success and heterozygosity, suggesting that this heritable characteristic is a reliable indicator of group quality and fitness. Given that heterozygosity predicts song structure in males, and can therefore be determined by listening to acoustic cues, we identify a mechanism by which social animals may assess rival groups, prospective partners and group mates, information of potential importance in guiding decisions related to conflict, breeding and dispersal.
| S-EPMC1691794 | biostudies-literature
Project description:Attempts to understand the causes of variation in senescence trajectories would benefit greatly from biomarkers that reflect the progressive declines in somatic integrity (SI) that lead to senescence. While telomere length has attracted considerable interest in this regard, sources of variation in telomere length potentially unrelated to declines in SI could, in some contexts, leave telomere attrition rates a more effective biomarker than telomere length alone. Here, we investigate whether telomere length and telomere attrition rates predict the survival of wild white-browed sparrow-weaver nestlings (Plocepasser mahali). Our analyses of telomere length reveal counterintuitive patterns: telomere length soon after hatching negatively predicted nestling survival to fledging, a pattern that appears to be driven by differentially high in-nest predation of broods with longer telomeres. Telomere length did not predict survival outside this period: neither hatchling telomere length nor telomere length in the mid-nestling period predicted survival from fledging to adulthood. Our analyses using within-individual telomere attrition rates, by contrast, revealed the expected relationships: nestlings that experienced a higher rate of telomere attrition were less likely to survive to adulthood, regardless of their initial telomere length and independent of effects of body mass. Our findings support the growing use of telomeric traits as biomarkers of SI, but lend strength to the view that longitudinal assessments of within-individual telomere attrition since early life may be a more effective biomarker in some contexts than telomere length alone.
| S-EPMC6772082 | biostudies-other
Project description:In socially monogamous animals, including humans, pairs can meet and spend time together before they begin reproduction. However, the pre-breeding period has been challenging to study in natural populations, and thus remains largely unexplored. As such, our understanding of the benefits of mate familiarity is almost entirely limited to assessments of repeated breeding with a particular partner. Here, we used fine-scale tracking technology to gather 6 years of data on pre-breeding social associations of individually marked great tits in a wild population. We show that pairs which met earlier in the winter laid their eggs earlier in all years. Clutch size, number of hatched and fledged young, and hatching and fledging success were not influenced by parents' meeting time directly, but indirectly: earlier laying pairs had larger clutches (that also produce higher number of young), and higher hatching and fledging success. We did not detect a direct influence of the length of the initial pairing period on future mating decisions (stay with a partner or divorce). These findings suggest a selective advantage for a new pair to start associating earlier (or for individuals to mate with those they have known for longer). We call for more studies to explore the generality of fitness effects of pair familiarity prior to first breeding, and to elucidate the mechanisms underlying these effects.
| S-EPMC7779496 | biostudies-literature
Project description:BackgroundSaccharomyces cerevisiae has been associated with human life for millennia in the brewery and bakery. Recently it has been recognized as an emerging opportunistic pathogen. To study the evolutionary history of S. cerevisiae, the origin of clinical isolates and the importance of a virulence-associated trait, population genetics and phenotypic assays have been applied to an ecologically diverse set of 103 strains isolated from clinics, breweries, vineyards, fruits, soil, commercial supplements and insect guts.Methodology/principal findingsDNA sequence data from five nuclear DNA loci were analyzed for population structure and haplotype distribution. Additionally, all strains were tested for survival of oxidative stress, a trait associated with microbial pathogenicity. DNA sequence analyses identified three genetic subgroups within the recombining S. cerevisiae strains that are associated with ecology, geography and virulence. Shared alleles suggest that the clinical isolates contain genetic contribution from the fruit isolates. Clinical and fruit isolates exhibit high levels of recombination, unlike the genetically homogenous soil isolates in which no recombination was detected. However, clinical and soil isolates were more resistant to oxidative stress than any other population, suggesting a correlation between survival in oxidative stress and yeast pathogenicity.Conclusions/significancePopulation genetic analyses of S. cerevisiae delineated three distinct groups, comprising primarily the (i) human-associated brewery and vineyard strains, (ii) clinical and fruit isolates (iii) and wild soil isolates from eastern U.S. The interactions between S. cerevisiae and humans potentiate yeast evolution and the development of genetically, ecologically and geographically divergent groups.
| S-EPMC2669729 | biostudies-literature
Project description:AMP-activated protein kinase (AMPK) is an energy sensor essential for maintaining cellular energy homeostasis. Here, we report that AMPKalpha1 is the predominant isoform of AMPK in murine erythrocytes and mice globally deficient in AMPKalpha1 (AMPKalpha1(-/-)), but not in those lacking AMPKalpha2, and the mice had markedly enlarged spleens with dramatically increased proportions of Ter119-positive erythroid cells. Blood tests revealed significantly decreased erythrocyte and hemoglobin levels with increased reticulocyte counts and elevated plasma erythropoietin concentrations in AMPKalpha1(-/-) mice. The life span of erythrocytes from AMPKalpha1(-/-) mice was less than that in wild-type littermates, and the levels of reactive oxygen species and oxidized proteins were significantly increased in AMPKalpha1(-/-) erythrocytes. In keeping with the elevated oxidative stress, treatment of AMPKalpha1(-/-) mice with the antioxidant, tempol, resulted in decreased reticulocyte counts and improved erythrocyte survival. Furthermore, the expression of Foxo3 and reactive oxygen species scavenging enzymes was significantly decreased in erythroblasts from AMPKalpha1(-/-) mice. Collectively, these results establish an essential role for AMPKalpha1 in regulating oxidative stress and life span in erythrocytes.
| S-EPMC2888409 | biostudies-literature
Project description:Identifying the causes and fitness consequences of intraspecific variation in cognitive performance is fundamental to understand how cognition evolves. Selection may act on different cognitive traits separately or jointly as part of the general cognitive performance (GCP) of the individual. To date, few studies have examined simultaneously whether individual cognitive performance covaries across different cognitive tasks, the relative importance of individual and social attributes in determining cognitive variation, and its fitness consequences in the wild. Here, we tested 38 wild southern pied babblers (Turdoides bicolor) on a cognitive test battery targeting associative learning, reversal learning and inhibitory control. We found that a single factor explained 59.5% of the variation in individual cognitive performance across tasks, suggestive of a general cognitive factor. GCP varied by age and sex; declining with age in females but not males. Older females also tended to produce a higher average number of fledglings per year compared to younger females. Analysing over 10 years of breeding data, we found that individuals with lower general cognitive performance produced more fledglings per year. Collectively, our findings support the existence of a trade-off between cognitive performance and reproductive success in a wild bird.
| S-EPMC9768653 | biostudies-literature