Outcomes of Brood Parasite–Host Interactions Mediated by Egg Matching: Common Cuckoos Cuculus canorus versus Fringilla Finches

Antagonistic species often interact via matching of phenotypes, and interactions between brood parasitic common cuckoos (Cuculus canorus) and their hosts constitute classic examples. The outcome of a parasitic event is often determined by the match between host and cuckoo eggs, giving rise to potentially strong associations between fitness and egg phenotype. Yet, empirical efforts aiming to document and understand the resulting evolutionary outcomes are in short supply.We used avian color space models to analyze patterns of egg color variation within and between the cuckoo and two closely related hosts, the nomadic brambling (Fringilla montifringilla) and the site fidelic chaffinch (F. coelebs). We found that there is pronounced opportunity for disruptive selection on brambling egg coloration. The corresponding cuckoo host race has evolved egg colors that maximize fitness in both sympatric and allopatric brambling populations. By contrast, the chaffinch has a more bimodal egg color distribution consistent with the evolutionary direction predicted for the brambling. Whereas the brambling and its cuckoo host race show little geographical variation in their egg color distributions, the chaffinch's distribution becomes increasingly dissimilar to the brambling's distribution towards the core area of the brambling cuckoo host race.High rates of brambling gene flow is likely to cool down coevolutionary hot spots by cancelling out the selection imposed by a patchily distributed cuckoo host race, thereby promoting a matching equilibrium. By contrast, the site fidelic chaffinch is more likely to respond to selection from adapting cuckoos, resulting in a markedly more bimodal egg color distribution. The geographic variation in the chaffinch's egg color distribution could reflect a historical gradient in parasitism pressure. Finally, marked cuckoo egg polymorphisms are unlikely to evolve in these systems unless the hosts evolve even more exquisite egg recognition capabilities than currently possessed

How do nutrient conditions and species identity influence the impact of mesograzers in eelgrass-epiphyte systems?

Coastal eutrophication is thought to cause excessive growth of epiphytes in eelgrass beds, threatening the health and survival of these ecologically and economically valuable ecosystems worldwide. Mesograzers, small crustacean and gastropod grazers, have the potential to prevent seagrass loss by grazing preferentially and efficiently on epiphytes. We tested the impact of three mesograzers on epiphyte biomass and eelgrass productivity under threefold enriched nutrient concentrations in experimental indoor mesocosm systems under summer conditions. We compared the results with earlier identical experiments that were performed under ambient nutrient supply. The isopod Idotea baltica, the periwinkle Littorina littorea, and the small gastropod Rissoa membranacea significantly reduced epiphyte load under high nutrient supply with Rissoa being the most efficient grazer, but only high densities of Littorina and Rissoa had a significant positive effect on eelgrass productivity. Although all mesograzers increased epiphyte ingestion with higher nutrient load, most likely as a functional response to the quantitatively and qualitatively better food supply, the promotion of eelgrass growth by Idotea and Rissoa was diminished compared to the study performed under ambient nutrient supply. Littorina maintained the level of its positive impact on eelgrass productivity regardless of nutrient concentrations

A multiple cohort study of the gender gradient of life satisfaction during adolescence: longitudinal evidence from Great Britain*

This study is unique in exploiting 12 youth cohorts (aged 11–15) from the British Household Panel Survey (BHPS) and the UK Household Longitudinal Study (UKHLS) spanning 1996–2017 to investigate the gender gradient of adolescent life satisfaction. We find robust evidence of a cross-cohort gender gap particularly at the extremes of the adolescent life satisfaction distribution. Male adolescents are significantly more likely to report complete life satisfaction (by around 6%–14%) and females to report dissatisfaction (by around 3%–7%) indicating a higher female depression propensity. An intra-household gender gap is found for female adolescents raised with opposite sex siblings. Previous period life satisfaction is the strongest determinant of prospective higher self-reported male satisfaction levels

Translation and linguistic validation of a swedish study-specific questionnaire for use among Norwegian parents who lost a child to cancer

Research is needed on how to help cancer-bereaved parents, as they are considered to be a vulnerable population and they are at risk of developing ill health following the loss of a child to cancer. The purpose of the present study was to translate and linguistically validate a Swedish study-specific questionnaire that was developed for Swedish cancer-bereaved parents. The translated questionnaire will be used in a nationwide study in Norway. Methods: Forward and backward translations of the Swedish study-specific questionnaire were conducted, followed by linguistic validation based on telephone interviews with six Norwegian cancer-bereaved parents. Result: It was found that several medical terms and conceptual issues were difficult for the Norwegian parents to understand. There were also four issues regarding the response alternatives. Conclusions: Although Sweden and Norway have quite similar cultures and languages, the results off this pilot study show that, to ensure the quality of a translated questionnaire, linguistic validation as well as translation is necessary

A holistic understanding of the effect of stress on adolescent well-being: a conditional process analysis

While traditional assumptions tend to conceptualise stress as inherently dysfunctional, psychological theory suggests it is not intrinsically maladaptive. Contemporary models emphasise that the stress response can be differentiated into both negative and positive aspects, known as distress and eustress. Research examining the differential effect of positive and negative stress on adolescent wellbeing is limited and has been hindered by a lack of appropriate measurement tools. The aim of the present study was to utilise the recently developed Adolescent Distress-Eustress Scale (ADES) to provide a balanced understanding of the impact of stress on positive mental health, holistically considering the effect of both distress and eustress on adolescent wellbeing. 1,081 Australian adolescents (Mage = 15.14, 54.03% female) completed an online survey comprising of the ADES alongside measures of wellbeing, self-efficacy, psychological illbeing, physical activity, and daytime sleepiness. Conditional Process Analysis suggested that distress exerted no direct influence on wellbeing, with the observed negative relationship fully mediated by psychological and behavioural variables. Contrastingly, eustress was both directly related to increased wellbeing and exerted an indirect effect through relationships with mediating variables. These results demonstrate that stress can have profoundly positive consequences. Theoretical contributions, implications for practice, and perspectives for future research are discussed.Victoria Branson, Edward Palmer, Matthew J. Dry, Deborah Turnbul