Data from: Heterozygosity-fitness correlations in a migratory bird: an analysis of inbreeding and single-locus effects

Studies in a multitude of taxa have described a correlation between heterozygosity and fitness, and usually conclude that this is evidence for inbreeding depression. Here we have used multi-locus heterozygosity estimates from 15 microsatellite markers to show evidence of heterozygosity-fitness correlations (HFCs) in a long-distance migratory bird, the light-bellied Brent goose. We found significant, positive heterozygosity-heterozygosity correlations between random subsets of the markers we employ, and no evidence that a model containing all loci as individual predictors in a multiple regression explained significantly more variation than a model with multi-locus heterozygosity as a single predictor. Collectively these results lend support to the hypothesis that the HFCs we have observed are a function of inbreeding depression. However, we do find that fitness correlations are only detectable in years where population-level productivity is high enough for the reproductive asymmetry between high and low heterozygosity individuals to become apparent. We suggest that lack of evidence of heterozygosity-fitness correlations in animal systems may be because heterozygosity is a poor proxy measure of inbreeding, especially when employing low numbers of markers, but alternatively because the asymmetries between individuals of different heterozygosities may only be apparent when environmental effects on fitness are less pronounced

Data from: Climatic conditions produce contrasting influences on demographic traits in a long distance Arctic migrant

The manner in which patterns of variation and interactions among demographic rates contribute to population growth rate (λ) is key to understanding how animal populations will respond to changing climatic conditions. Migratory species are likely to be particularly sensitive to climatic conditions as they experience a range of different environments throughout their annual cycle. However, few studies have provided fully integrated demographic analyses of migratory populations in response to changing climatic conditions. Here, we employed integrated population models to demonstrate that the environmental conditions experienced during a short but critical period play a central role in the demography of a long-distance migrant, the light-bellied Brent goose (Branta bernicla hrota). Female survival was positively associated with June North Atlantic Oscillation (NAO) values, whereas male survival was not. In contrast, breeding productivity was negatively associated with June NAO, suggesting a trade-off between female survival and reproductive success. Both adult female and adult male survival showed low temporal variation, whereas there was high temporal variation in recruitment and breeding productivity. In addition, while annual population growth was positively correlated with annual breeding productivity, a sensitivity analysis revealed that population growth was most sensitive to changes in adult survival. Our results demonstrate that the environmental conditions experienced during a relatively short-time window at the start of the breeding season play a critical role in shaping the demography of a long-distant Arctic migrant. Crucially, different demographic rates responded in opposing directions to climatic variation, emphasising the need for integrated analysis of multiple demographic traits when understanding population dynamics

M Arrays for adults and juveniles

Survival histories in M Array format for adult females, adult males and juveniles. Note juvenile goslings were only ringed in one year of the present stud

Carry-over effects reveal reproductive costs in a long-distance migrant

It has been known for some time that the consequences of 'decisions' made at one point in an animal's life may not always be borne immediately. For example, numerous studies have demonstrated the trade-off between current and future breeding success across multiple taxa. 2. It is becoming increasingly clear that such processes may also operate among seasons, such that the conditions experienced at one point in the annual cycle may have significant downstream impacts, or 'carry-over effects', and this is particularly evident among migratory species. We might therefore predict that certain combinations of reproductive and migratory strategy could lead to profound carry-over effects. However, the extent to which these phenomena might generate variation in fitness within a population is unclear.3. Here, we investigate how winter habitat selection in a long-distance migrant, with extended parental care (the Light-bellied Brent goose) is influenced by parental status and how this has a counterintuitive effect on subsequent breeding success.4. Dominant individuals and groups generally monopolize the best quality resources. In the case of geese, families are dominant; however, our findings highlight a hidden cost to raising a family. Stable isotope analysis demonstrates that later in the non-breeding season, adults with families utilize lower quality resources than non-breeders. This is probably caused by parents being constrained in habitat choice by the lower foraging efficiency of their juveniles. Consequently, parental adults end the winter in poorer condition than non-breeders.5. We further demonstrate that parents in one year are less likely than expected to breed again in the next year and suggest that this is caused by conditions during the non-breeding period being carried over into the breeding season. In conclusion, we demonstrate previously hidden costs to raising a family, which are likely to be important in terms of life-history evolution

Individual Genotypes

Individual Genotype

Environmental Conditions during Breeding Modify the Strength of Mass-Dependent Carry-Over Effects in a Migratory Bird

<div><p>In many animals, processes occurring in one season carry over to influence reproductive success and survival in future seasons. The strength of such carry-over effects is unlikely to be uniform across years, yet our understanding of the processes that are capable of modifying their strength remains limited. Here we show that female light-bellied Brent geese with higher body mass prior to spring migration successfully reared more offspring during breeding, but only in years where environmental conditions during breeding were favourable. In years of bad weather during breeding, all birds suffered reduced reproductive output irrespective of pre-migration mass. Our results suggest that the magnitude of reproductive benefits gained by maximising body stores to fuel breeding fluctuates markedly among years in concert with conditions during the breeding season, as does the degree to which carry-over effects are capable of driving variance in reproductive success among individuals. Therefore while carry-over effects have considerable power to drive fitness asymmetries among individuals, our ability to interpret these effects in terms of their implications for population dynamics is dependent on knowledge of fitness determinants occurring in subsequent seasons. </p> </div

Graph illustrating how the strength of mass-dependent carry-over effects is modulated by the environmental conditions during breeding.

<p>In years with positive June NAO (red line), representative of poor weather conditions during breeding, higher body mass does not yield an increase in reproductive success. Conversely, when breeding conditions are favourable (Negative June NAO, blue line), individuals with greater body mass return the following year with more offspring. The x axis represents body mass (as Scaled Mass Index) expressed in units of standard deviations from the mean, where ‘0’ represents an individual of average mass in the sample. Shaded areas span the 95% credible intervals for the fitted means. Points are raw data means for years with positive June NAO (triangles) and negative June NAO (circles), averaged over 1 SD bins of body mass and plotted at the midpoint of that bin. Point size is proportional to sample size per bin. Sample size per bin is displayed next to each point. Predictions for both good and poor environmental conditions are for ‘average' conditions in each scenario, being the mean of years with negative NAO residuals for ‘good’ years and mean positive residuals for ‘bad’ years. Note that as the data predict over values within 1.5 SD of mean body mass, some data at the tails of the distribution for body mass are excluded from the plot. </p

Demographic rates reveal the benefits of protected areas in a long-lived migratory bird

Recent studies have suggested that protected areas often fail to conserve target species. However, the efficacy of terrestrial protected areas is difficult to measure, especially for highly vagile species like migratory birds that may move between protected and unpro-tected areas throughout their lives. Here, we use a 30-y dataset of detailed demographic data from a migratory waterbird, the Whooper swan (Cygnus cygnus), to assess the value of nature reserves (NRs). We assess how demographic rates vary at sites with varying levels of protection and how they are influenced by movements between sites. Swans had a lower breeding probability when wintering inside NRs than outside but better survival for all age classes, generating a 30-fold higher annual growth rate within NRs. There was also a net movement of individuals from NRs to non-NRs. By combining these demographic rates and estimates of movement (into and out of NRs) into popu-lation projection models, we show that the NRs should help to double the population of swans wintering in the United Kingdom by 2030. These results highlight the major effect that spatial management can have on species conservation, even when the areas protected are relatively small and only used during short periods of the life cycle.Peer reviewe

Long-term effectiveness of dopamine agonists and monoamine oxidase B inhibitors compared with levodopa as initial treatment for Parkinson\u27s disease (PD MED): A large, open-label, pragmatic randomised trial

\ua9 2014 Elsevier Ltd. Background Whether initial treatment for Parkinson\u27s disease should consist of levodopa, dopamine agonists, or monoamine oxidase type B inhibitors (MAOBI) is uncertain. We aimed to establish which of these three classes of drug, as initial treatment, provides the most effective long-term control of symptoms and best quality of life for people with early Parkinson\u27s disease. Methods In this pragmatic, open-label randomised trial, patients newly diagnosed with Parkinson\u27s disease were randomly assigned (by telephone call to a central office; 1:1:1) between levodopa-sparing therapy (dopamine agonists or MAOBI) and levodopa alone. Patients and investigators were not masked to group assignment. Primary outcomes were the mobility dimension on the 39-item patient-rated Parkinson\u27s disease questionnaire (PDQ-39) quality-of-life scale (range 0-100 with six points defined as the minimally important difference) and cost-effectiveness. Analysis was intention to treat. This trial is registered, number ISRCTN69812316. Findings Between Nov 9, 2000, and Dec 22, 2009, 1620 patients were assigned to study groups (528 to levodopa, 632 to dopamine agonist, 460 to MAOBI). With 3-year median follow-up, PDQ-39 mobility scores averaged 1\ub78 points (95% CI 0\ub75-3\ub70, p=0\ub7005) better in patients randomly assigned to levodopa than those assigned to levodopa-sparing therapy, with no increase or attrition of benefit during 7 years\u27 observation. PDQ-39 mobility scores were 1\ub74 points (95% CI 0\ub70-2\ub79, p=0\ub705) better in patients allocated MAOBI than in those allocated dopamine agonists. EQ-5D utility scores averaged 0\ub703 (95% CI 0\ub701-0\ub705; p=0\ub70002) better with levodopa than with levodopa-sparing therapy; rates of dementia (hazard ratio [HR] 0\ub781, 95% CI 0\ub761-1\ub708, p=0\ub714), admissions to institutions (0\ub786, 0\ub763-1\ub718; p=0\ub74), and death (0\ub785, 0\ub769-1\ub706, p=0\ub717) were not significantly different, but the upper CIs precluded any substantial increase with levodopa compared with levodopa-sparing therapy. 179 (28%) of 632 patients allocated dopamine agonists and 104 (23%) of 460 patients allocated MAOBI discontinued allocated treatment because of side-effects compared with 11 (2%) of 528 patients allocated levodopa (p&lt;0\ub70001). Interpretation Very small but persistent benefits are shown for patient-rated mobility scores when treatment is initiated with levodopa compared with levodopa-sparing therapy. MAOBI as initial levodopa-sparing therapy was at least as effective as dopamine agonists. Funding UK National Institute for Health Research Health Technology Assessment Programme and UK Department of Health