The strong association observed between fire regimes and variation in plant adaptations to fire suggests a rapid response to fire as an agent of selection. It also suggests that fire-related traits are heritable, a precondition for evolutionary change. One example is serotiny, the accumulation of seeds in unopened fruits or cones until the next fire, an important strategy for plant population p...

The ratio of the lengths of the second to fourth digits of the hand (2D:4D) is a sexually dimorphic trait that has been proposed as a measure of prenatal testosterone exposure and a putative correlate of a variety of later behavioral and physiological outcomes including personality, fitness and sexual orientation. We present analyses of 2D:4D ratios collected from twins (1413 individuals) and t...

The effect of genetic and non-genetic factors for carcass, breast meat and leg weights, and yields of a commercial broiler line were investigated using the restricted maximum likelihood method, considering four different animal models, including or excluding maternal genetic effect with covariance between direct and maternal genetic effects, and maternal permanent environmental effect. The like...

AIMS To examine the heritability of cannabis initiation, the influence of a possible twin-specific environment and the influence of age on the effects of genes and environment in Dutch adolescents and young adults. DESIGN Genetic structural equation modelling was used to partition the variance in the liability to cannabis initiation into genetic and environmental components. SETTING All par...

Aims To examine the heritability of cannabis initiation, the influence of a possible twin-specific environment and the influence of age on the effects of genes and environment in Dutch adolescents and young adults. Design Genetic structural equation modelling was used to partition the variance in the liability to cannabis initiation into genetic and environmental components. Setting All partici...

BACKGROUND We sought by use of an adult twin study to investigate the relative contribution of genetic and environmental effects on the expression of nevi and freckles, which are known risk factors for melanoma, and to determine if age and sun exposure influence the heritability of nevi. DESIGN AND METHODS Total nevus and freckle counts were conducted on 127 monozygotic twin pairs and 323 diz...

This study investigated the association between environmental mastery and depression in a sample of 96 older adults (aged 64–98 years) in residential care. The participants completed a scale that assessed depression along with measures for risk factors for depression such as functional capacity, self-evaluated physical health, bereavement experiences and environmental mastery. The results showe...

Recent research in ecology has concentrated on the effect of environmental changes on ecosystem structure and function. In most cases the focus has been on how ecosystems respond to changes in the mean values of environmental parameters, while the impact of changes in the variance has seldom been studied. However, changes in environmental variability may be important. For example, recent climat...

OBJECTIVE Subjective health is a complex indicator predicting longevity independent of objective health. Few studies examine genetic and environmental mechanisms underlying different facets of subjective health across the life course. METHOD Three subjective health measures were examined in 12,900 twins ( Mage = 63.38, range = 25-102) from nine studies in the Interplay of Genes and Environmen...

Previous research has indicated that extraversion and neuroticism are substantially affected both by genotype and environment. This study assesses genetic and environmental influences on the other three components of the five-factor model of personality: Openness to Experience, Agreeableness, and Conscientiousness. An abbreviated version of the NEO Personality Inventory (NEO-PI) was administere...