Experimentally increased brood size accelerates actuarial senescence and increases subsequent reproductive effort in a wild bird population

The assumption that reproductive effort decreases somatic state, accelerating ageing, is central to our understanding of life‐history variation. Maximal reproductive effort early in life is predicted to be maladaptive by accelerating ageing disproportionally, decreasing fitness. Optimality theory predicts that reproductive effort is restrained early in life to balance the fitness contribution of reproduction against the survival cost induced by the reproductive effort. When adaptive, the level of reproductive restraint is predicted to be inversely linked to the remaining life expectancy, potentially resulting in a terminal effort in the last period of reproduction. Experimental tests of the reproductive restraint hypothesis require manipulation of somatic state and subsequent investigation of reproductive effort and residual life span. To our knowledge the available evidence remains inconclusive, and hence reproductive restraint remains to be demonstrated. We modulated somatic state through a lifelong brood size manipulation in wild jackdaws and measured its consequences for age‐dependent mortality and reproductive success. The assumption that lifelong increased brood size reduced somatic state was supported: Birds rearing enlarged broods showed subsequent increased rate of actuarial senescence, resulting in reduced residual life span. The treatment induced a reproductive response in later seasons: Egg volume and nestling survival were higher in subsequent seasons in the increased versus reduced broods' treatment group. We detected these increases in egg volume and nestling survival despite the expectation that in the absence of a change in reproductive effort, the reduced somatic state indicated by the increased mortality rate would result in lower reproductive output. This leads us to conclude that the higher reproductive success we observed was the result of higher reproductive effort. Our findings show that reproductive effort negatively covaries with remaining life expectancy, supporting optimality theory and confirming reproductive restraint as a key factor underpinning life‐history variation

Higher mercury contamination is associated with shorter telomeres in a long-lived seabird – A direct effect or a consequence of among-individual variation in phenotypic quality?

Mercury is a heavy metal, which is pervasive and persistent in the marine environment. It bioaccumulates within organisms and biomagnifies in the marine food chain. Due to its high toxicity, mercury contamination is a major concern for wildlife and human health. Telomere length is a biomarker of aging and health, because it predicts survival, making it a potential tool to investigate sublethal effects of mercury contamination. However, the relationship between telomeres and mercury contamination is unclear. We measured feather mercury concentration in Cory's Shearwaters Calonectris borealis, long-lived seabirds and top predators, between 9 and 35 years of age and related it to telomere length in erythrocytes. Cory's Shearwaters with higher mercury concentrations had shorter telomeres and the effect was sex-dependent, reaching significance in males only. This may be explained by the fact that males have longer telomeres and higher and more variable mercury concentrations than females in this population. The mercury effect on telomere length was stronger on longer telomeres in the genome within individuals. We discuss the hypotheses that the negative correlation could either be a direct effect of mercury on telomere shortening and/or a consequence of variation in phenotypic quality among individuals that results in a covariation between mercury contamination and telomere length.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Telomere length is repeatable, shortens with age and reproductive success, and predicts remaining lifespan in a long-lived seabird

Telomeres are protective caps at the end of chromosomes, and their length is positively correlated with individual health and lifespan across taxa. Longitudinal studies have provided mixed results regarding the within-individual repeatability of telomere length. While some studies suggest telomere length to be highly dynamic and sensitive to resource-demanding or stressful conditions, others suggest that between-individual differences are mostly present from birth and relatively little affected by the later environment. This dichotomy could arise from differences between species, but also from methodological issues. In our study, we used the highly reliable Terminal Restriction Fragment analysis method to measure telomeres over a 10-year period in adults of a long-lived seabird, the common tern (Sterna hirundo). Telomeres shortened with age within individuals. The individual repeatability of age-dependent telomere length was high (>0.53), and independent of the measurement interval (i.e., one vs. six years). A small (R-2 = .01), but significant part of the between-individual variation in telomere length was, however, explained by the number of fledglings produced in the previous year, while reproduction in years prior to the previous year had no effect. We confirmed that age-dependent telomere length predicted an individual's remaining lifespan. Overall, our study suggests that the majority of between-individual variation in adult telomere length is consistent across adult life, and that a smaller part of the variation can be explained by dynamic factors, such as reproduction

Costs of reproduction and migration are paid in later return to the colony, not in physical condition, in a long-lived seabird

Life history theory suggests a trade-off between costly activities such as breeding and migration and somatic self-maintenance. However, how the short-term cost of parental effort is expressed in species with a slow pace-of-life is not well understood. Also, investigating carry-over effects of migration is most meaningful when comparing migratory strategies within the same population, but this has rarely been done. We explore this hypothesis in a long-lived, pelagic seabird, the Cory's Shearwater, Calonectris borealis, where males display partial migration. By manipulating reproductive effort and taking advantage of the natural variation in migratory strategy, we investigate whether early reproductive failure and migratory strategy had implications on the physical condition of males on return to the colony the following year. We experimentally induced breeding failure from mid-incubation, tracked the over-winter movements of these males and of males that invested in parental effort, and assessed innate immunity, stress, and residual body mass the following year. Early breeding failure resulted in earlier return to the colony among all males, associated with greater probability of reproductive success. Residents had a lower tail feather fault bar intensity, an indicator of stress during the non-breeding period, compared to migrants. Reproductive effort and migratory strategy had no impact on physiological condition otherwise. Our results provide evidence that in species with a slow-pace of life, such as the Cory's Shearwater, somatic maintenance is prioritised, with the costs of reproduction and migration paid in delayed arrival date.FCT - Fundação para a Ciência e Tecnologiainfo:eu-repo/semantics/publishedVersio

Ectoparasite presence and brood size manipulation interact to accelerate telomere shortening in nestling jackdaws

Early‐life conditions impact fitness, but whether the combined effect of extrinsic stressors is additive or synergistic is not well known. This is a major knowledge gap because exposure to multiple stressors is frequent. Telomere dynamics may be instrumental when testing how stressors interact because many factors affect telomere shortening, and telomere shortening predicts survival. We evaluated the effect of manipulated brood size and natural infestation by the carnid fly Carnus hemapterus on nestling growth and telomere shortening of wild jackdaws (Corvus monedula). Telomere length, measured in blood using TRF, shortened on average by 264 bp, and on average, Carnus infection induced more telomere shortening. Further analyses showed that in enlarged broods, nestlings' telomeres shortened more when parasitized, while in reduced broods there was no effect of infection on telomere shortening. We conclude that there is a synergistic effect of number of siblings and Carnus infection on telomere shortening rate: blood‐sucking parasites may negatively impact telomeres by increasing cell proliferation and/or physiological stress, and coping with infection may be less successful in enlarged broods with increased sibling competition. Larger nestlings had shorter telomeres independent of age, brood manipulation or infection. Growth was independent of infestation but in enlarged broods, nestlings were lighter at fledging. Our findings indicate that (i) evaluating consequences of early‐life environmental conditions in isolation may not yield a full picture due to synergistic effects, and (ii) effects of environmental conditions may be cryptic, for example, on telomeres, with fitness consequences expressed beyond the temporal framework of the study

Using supply chain data to monitor zero deforestation commitments: an assessment of progress in the Brazilian soy sector

Zero deforestation commitments (ZDCs) are voluntary initiatives where companies or countries pledge to eliminate deforestation from their supply chains. These commitments offer much promise for sustainable commodity production, but are undermined by a lack of transparency about their coverage and impacts. Here, using state-of-the-art supply chain data, we introduce an approach to evaluate the impact of ZDCs, linking traders and international markets to commodity-associated deforestation in the sub-national jurisdictions from which they source. We focus on the Brazilian soy sector, where we find that ZDC coverage is increasing, but under-represents the Cerrado biome where most soy-associated deforestation currently takes place. Though soy-associated deforestation declined in the Amazon after the introduction of the Soy Moratorium, we observe no change in the exposure of companies or countries adopting ZDCs to soy-associated deforestation in the Cerrado. We further assess the formulation and implementation of these ZDCs and identify several systematic weaknesses that must be addressed to increase the likelihood that they achieve meaningful reductions in deforestation in future. As the 2020 deadline for several of these commitments approaches, our approach can provide independent monitoring of progress toward the goal of ending commodity-associated deforestation

Das Stigma von Suchterkrankungen verstehen und überwinden = Understanding and overcoming the stigma of substance use disorders

Understanding and overcoming the stigma of substance use disorders Abstract. Stigma does harm to individuals with substance use disorders (SUD), and it increases the burden of SUDs. It presents a barrier to help seeking, results in lower treatment quality and increases social and health related consequences of SUDs. This applies to both the individual, societal and economic consequences of substance use. Moreover, stigmatizing persons with addictions is an ethical problem, since it discriminates against a certain group and infringes on their human dignity. Dealing with substance use disorders without stigma is possible. Eliminating the stigma of SUDs means finding better ways to deal with SUDs and to make these ways available to everyone. Instead of devaluing, marginalizing and disciplining persons with SUD, empowerment and appreciation need to be at the core of dealing with SUD in prevention, treatment and every day life

Data from: Within the genome, long telomeres are more informative than short telomeres with respect to fitness components in a long-lived seabird

Telomeres, DNA-protein structures at chromosome ends, shorten with age, and telomere length has been linked to age-related diseases and survival. In vitro studies revealed that the shortest telomeres trigger cell senescence, but whether the shortest telomeres are also the best biomarker of ageing is not known. We measured telomeres in erythrocytes of wild common terns Sterna hirundo using terminal restriction fragment analysis. This yields a distribution of telomere lengths for each sample, and we investigated how different telomere subpopulations (percentiles) varied in their relation to age and fitness proxies. Longer telomeres within a genome lost more base pairs with age and were better predictors of survival than shorter telomeres. Likewise, fitness proxies such as arrival date at the breeding grounds and reproductive success were best predicted by telomere length at the higher percentiles. Our finding that longer telomeres within a genome predict fitness components better than the shorter telomeres indicates that they are a more informative ageing biomarker. This finding contrasts with the fact that cell senescence is triggered by the shortest telomeres. We suggest that this paradox arises, because longer telomeres lose more base pairs per unit time and thus better reflect the various forms of stress that accelerate telomere shortening, and that telomeres primarily function as biomarker because their shortening reflects cumulative effects of various stressors rather than reflecting telomere-induced cell senescence

Data from: Telomere length reflects phenotypic quality and costs of reproduction in a long-lived seabird

Telomere length is associated with cellular senescence, lifestyle and ageing. Short telomeres indicate poor health in humans and reduced life expectancy in several bird species, but little is known about telomeres in relation to phenotypic quality in wild animals. We investigated telomere lengths in erythrocytes of known-age common terns (Sterna hirundo), a migratory seabird, in relation to arrival date and reproductive performance. Cross-sectional data revealed that, independent of age, individuals with short telomeres performed better: they arrived and reproduced earlier in the season and had more chicks in the nest. The latter effect was stronger the older the brood and stronger in males, which do most of the chick provisioning. Longitudinal data confirmed this pattern: compared with birds that lost their brood, birds that raised chicks beyond the 10th nestling day experienced higher telomere attrition from one year to the next. However, more detailed analysis revealed that the least and most successful individuals lost the fewest base pairs compared with birds with intermediate success. Our results suggest that reproductive success is achieved at the expense of telomeres, but that individual heterogeneity in susceptibility to such detrimental effects is important, as indicated by low telomere loss in the most successful birds