Individual heterogeneity and senescence in Silvereyes on Heron Island

Individual heterogeneity and correlations between life history traits play a fundamental role in life history evolution and population dynamics. Unobserved individual heterogeneity in survival can be a nuisance for estimation of age effects at the individual level by causing bias due to mortality selection. We jointly analyze survival and breeding output from successful breeding attempts in an island population of Silvereyes (Zosterops lateralis chlorocephalus) by fitting models that incorporate age effects and individual heterogeneity via random effects. The number of offspring produced increased with age of parents in their first years of life but then eventually declined with age. A similar pattern was found for the probability of successful breeding. Annual survival declined with age even when individual heterogeneity was not accounted for. The rate of senescence in survival, however, depends on the variance of individual heterogeneity and vice versa; hence, both cannot be simultaneously estimated with precision. Model selection supported individual heterogeneity in breeding performance, but we found no correlation between individual heterogeneity in survival and breeding performance. We argue that individual random effects, unless unambiguously identified, should be treated as statistical nuisance or taken as a starting point in a search for mechanisms rather than given direct biological interpretation

Invest in Primary Health Care and Public Health for the Pandemic and Beyond:An ASPHER Statement

info:eu-repo/semantics/publishedVersio

A Study of Obscuration in Catadioptric Lenses

In this paper we will examine the effect of obscuration upon the various features we desired to image with a 157nm microstepper utilising a catadioptric lens. We will show the effect the obscuration has upon imaging when using not only conventional illumination and binary masks, but also when using a range of enhancement techniques such as off-axis illumination and phase-shifting masks. We will show how use of a large obscuration, whilst enhancing the signals for the densest features, actually degrades the signal for more isolated features. The level of obscuration must also take into account cross duty-ratio effects, i.e. the distribution of diffraction energy, for phase shifted features of various sizes. In this situation where a small sigma would be used a large level of obscuration can significantly increase biases. The choice of obscuration can have a major effect upon the imaging capabilities of a tool. In future, when the use of catadioptric lenses may be more widespread (for example this may happen at 157nm) it may be desirable to have the option to vary this obscuration dependant upon the pattern being imaged

Predicting the impacts of chemical pollutants on animal groups

Wildlife are exposed to an increasing number and diversity of chemical pollutants.Chemical pollutants can elicit a range of sublethal effects on individual organisms, but research on how these contaminants affect social interactions and animal groups is severely lacking.It is imperative that perspectives from behavioural ecology and ecotoxicology are integrated, to increase our understanding of how contaminant effects on individuals might cascade to group-level processes.We present a conceptual framework for researchers and practitioners to guide the study of how chemical pollutants might affect the emergence, organisation, and function of animal social groups.Chemical pollution is among the fastest-growing agents of global change. Synthetic chemicals with diverse modes-of-action are being detected in the tissues of wildlife and pervade entire food webs. Although such pollutants can elicit a range of sublethal effects on individual organisms, research on how chemical pollutants affect animal groups is severely lacking. Here we synthesise research from two related, but largely segregated fields – ecotoxicology and behavioural ecology – to examine pathways by which chemical contaminants could disrupt processes that govern the emergence, self-organisation, and collective function of animal groups. Our review provides a roadmap for prioritising the study of chemical pollutants within the context of sociality and highlights important methodological advancements for future research