Phenotypic and social effects on behavioural trade-offs in Eurasian perch

Trading between conflicting demands is a fundamental part in how animals interact with its environment and social surrounding. Knowledge of what factors that are affecting behavioural decisions is central in our understanding of animal adaptation and ecology. This thesis summarizes a series of behavioural experiments investigating how animals compromise behaviours depending on environmental background and context. The focus is on within- and between-population variation in risk-taking and social trade-offs in young of the year and one year old Eurasian perch. Perch behaviour was quantified by observational studies in aquaria, using standardized assays that captured perch boldness and sociability. Perch from different predation backgrounds were compared in common garden experiments, as well as in multi-year inter-population comparisons, to study influence of predation experience on risk-taking phenotype. Results demonstrate predation as an important factor underlying how perch balance risk. Variation in risk-taking phenotype could to a large extent be explained by individual differences in experience of predation, rather than by fixed inherited responses caused by divergent selection. Experience of predation had long lasting effects on perch boldness, but perch were also able to quickly adjust phenotype in response to current conditions, indicating temporal flexibility in how experience shape behaviour. Social context influenced behaviour, with fish being bolder in larger group, and showing higher behavioural conformity. Occurrence of consistent individual variation in risk-taking and social behaviour could be established, confirming the existence of a personality dimension in perch behaviour. The thesis concludes that variation in how perch trade-off conflicting behaviours exists at multiple levels, from population to individual. Behavioural plasticity, even in strongly fitness related traits, is evident, although potential behavioural constraints in the form of consistent individuality is also present

A Note on the Variability of V538 Cassiopeiae

CCD observations of V538 Cas have been made on nine nights during three weeks using the AAVSO Bright Star Monitor. No significant variations were found.Comment: To be published in The Journal of the American Association Of Variable Star Observers (JAAVSO

Gotzmann's persistence theorem for finite modules

We prove a generalization of Gotzmann's persistence theorem in the case of modules with constant Hilbert polynomial. As a consequence, we show that the defining equations that give the embedding of a Quot scheme of points into a Grassmannian are given by a single Fitting ideal.Comment: 13 pages; restructured the paper and clarified some proof

Arthur Lewis' Contribution to Development Thinking and Policy

Arthur Lewis' seminal 1954 paper and its emphasis on dualism appeared at a time when neither the work of Keynes or Harrod-Domar nor the later neoclassical production function of Solow seemed relevant for developing countries. As a consequence, his model, rooted in the classical tradition, plus its many extensions, generated an extensive literature at the center of development theory. The approach also encountered increasingly strong criticism, some of the "red herring" variety, but some, spearheaded by neoclassical microeconomists like Rosenzweig, also raised serious challenges, focused especially on its labor market assumptions. This paper reviews this landscape and asks what theoretical or policy relevance the Lewis model retains for today's developing countries.Development Theory, Dualism, Labor Markets

Record of Graduation Letter for Ada Gillett

This letter from Linfield College registrar G.R. Schlauch to an unknown party (most likely Ada (Gillett) Rich) confirms her graduation from Linfield in 1920. The letter functions as a transcript, showing all classes taken, as well as how long the classes were, how many credits were earned per class, and the grade. Gillett graduated from Linfield with degrees in philosophy and music. This letter also served as a recommendation to any state Board of Education so she could apply for a teaching certificate.https://digitalcommons.linfield.edu/lca_rich/1003/thumbnail.jp