Search results for "selection"
showing 10 items of 1940 documents
Pressure to drink but not to smoke: Disentangling selection and socialization in adolescent peer networks and peer groups
2010
Contains fulltext : 90699.pdf (Publisher’s version ) (Closed access) This paper examined the relative influence of selection and socialization on alcohol and tobacco use in adolescent peer networks and peer groups. The sample included 1419 Finnish secondary education students (690 males and 729 females, mean age 16 years at the outset) from nine schools. Participants identified three school friends and described their alcohol and tobacco use on two occasions one year apart. Actor-based models simultaneously examined changes in peer network ties and changes in individual behaviors for all participants within each school. Multi-level analyses examined changes in individual behaviors for adole…
The development of analogy making in children: cognitive load and executive functions.
2010
The aim of the current study was to investigate the performance of 6-, 8-, and 14-year-olds on an analogy-making task involving analogies in which there are competing perceptual and relational matches. We hypothesized that the selection of the common relational structure requires the inhibition of other salient features, in particular, perceptual matches. Using an A:B::C:D paradigm, we showed that children’s performance in analogy-making tasks depends crucially on the nature of the distractors. Children chose more perceptual distractors having a common feature with C compared with A or B (Experiment 1). In addition, they were also influenced by unstructured random textures. When measuring r…
Color Signals in the Black Grouse (Tetrao tetrix): Signal Properties and Their Condition Dependency
2009
Recent progress in techniques of quantifying between-individual differences of color-based ornaments has revealed undiscovered possibilities for research in sexual selection. We present how the color spectra data can be comprehensively used for studying the importance of sexual ornaments in the black grouse and how these ornaments are related to a male condition. For this, we used both correlative field and experimental data. Field data indicated that older males had more chromatic coloration than yearlings. Blue chroma of males was correlated with male mating success. We experimentally manipulated yearling birds with testosterone implants and found that testosterone-implanted males had imp…
Parental effects on offspring longevity--evidence from 17th to 19th century reproductive histories.
2004
Family studies provide support for a modest genetic influence on offspring life span, although the magnitude of these correlations is small.The study aimed to clarify the relative contributions of parental age at birth and overall parental longevity on offspring lifespan, and to identify the biological and cultural mechanisms.Information was derived from two village genealogies (1650-1927) encompassing 9979 births (5315 males, 4664 females). Data selection was guided by the inclusion of information about parental age at birth and lifespan, offspring lifespan and cohort-specific life expectancy.Parental age at reproduction displayed a negative association with offspring survivability, which …
Female control of paternity in the sexually cannibalistic spider Argiope keyserlingi.
2000
Sexual conflict theory predicts an antagonistic coevolution, with each sex evolving adaptations and counter-adaptations to overcome a temporary dominance of the other sex over the control of paternity. Polyandry allows sexual selection to operate after mating has commenced, with male and female interests competing for control of fertilization. There are numerous examples of male control of paternity, but few studies have unambiguously revealed female control. Attributing variance in paternity to females is often difficult since male and female influences cannot be separated unambiguously. However, we show that polyandrous female orb-web spiders Argiope keserlingi (Arancidae) control the pat…
Functional annulus remodelling using a prosthetic ring in tricuspid aortic valve repair: mid-term results
2013
OBJECTIVES: The functional aortic valve annulus (FAVA) is a complex unit with proximal (aorto-ventricular junction) and distal (sinotubular junction) components. The aim of our study was to evaluate the impact of the total FAVA remodelling, using a prosthetic ring, on mid-term clinical and echocardiographic-RESULTS:-after aortic valve repair. METHODS: Since February 2003, 250 patients with tricuspid aortic valve insufficiency (AI) underwent aortic valve repair. FAVA dilatation was treated by prosthetic ring in 52 patients, by isolated subcommissural plasty in 62, by subcommissural plasty plus ascending aortic replacement in 57 and by David's reimplantation procedure in 79. Survival rate and…
Incentive and Selection Effects of Medigap Insurance on Inpatient Care
2012
The Medicare program, which provides insurance coverage to the elderly in the United States, does not protect them fully against high out-of-pocket costs. For this reason private supplementary insurance, named Medigap, has been available to cover Medicare gaps. This paper studies how Medigap affects the utilization of inpatient care, separating the incentive and selection effects of supplementary insurance. For this purpose, we use two alternative estimation methods: a standard recursive bivariate probit and a discrete multivariate finite mixture model. We find that estimated incentive effects are modest and quite similar across models. On the other hand, there seems to be very significant …
Polyandry enhances offspring survival in an infanticidal species
2009
The adaptive significance of polyandry is an intensely debated subject in sexual selection. For species with male infanticidal behaviour, it has been hypothesized that polyandry evolved as female counterstrategy to offspring loss: by mating with multiple males, females may conceal paternity and so prevent males from killing putative offspring. Here we present, to our knowledge, the first empirical test of this hypothesis in a combined laboratory and field study, and show that multiple mating seems to reduce the risk of infanticide in female bank voles Myodes glareolus . Our findings thus indicate that females of species with non-resource based mating systems, in which males provide nothing…
Raiders from the sky: slavemaker founding queens select for aggressive host colonies.
2012
Reciprocal selection pressures in host–parasite systems drive coevolutionary arms races that lead to advanced adaptations in both opponents. In the interactions between social parasites and their hosts, aggression is one of the major behavioural traits under selection. In a field manipulation, we aimed to disentangle the impact of slavemaking ants and nest density on aggression of Temnothorax longispinosus ants. An early slavemaker mating flight provided us with the unique opportunity to study the influence of host aggression and demography on founding decisions and success. We discovered that parasite queens avoided colony foundation in parasitized areas and were able to capture more broo…
Immune activation rapidly mirrored in a secondary sexual trait.
2003
A crucial assumption underlying most models of sexual selection is that sexual advertisements honestly reflect the phenotypic and/or genetic quality of their bearers ([1][1]). Here we show that experimental activation of the immune system is rapidly mirrored in the expression of a carotenoid-based