Personality and Alcohol Use across College: Examining Context-Dependent Pathways toward Alcohol Problems.

BACKGROUND: College life is characterized by marked increases in alcohol consumption. Extraversion and neuroticism are associated with alcohol use problems in college and throughout adulthood, each with alcohol use patterns consistent with an externalizing and internalizing pathway respectively. Students higher in extraversion drink more frequently and consume more alcohol, while neuroticism is paradoxically not consistently associated with elevated alcohol use. OBJECTIVE: This study examined whether students higher in neuroticism may drink the day before stressors, namely tests and assignment deadlines. METHOD: Multilevel generalized linear models were performed using data from a longitudinal study of first-time, first-year undergraduates assessing alcohol use across four years of college, with daily diary bursts each semester. RESULTS: Students higher in extraversion had heavier alcohol use and greater alcohol use problems in their fourth year of college. Neuroticism was not associated with drinking behaviors or with drinking before a test or assignment, but was associated with greater fourth year alcohol problems. Students lower in extraversion who reduced heavy drinking the day before academic events had fewer alcohol use problems at the fourth year of college relative to students higher in extraversion. CONCLUSIONS: Students higher in extraversion appear to exhibit a continuity of established alcohol use patterns from adolescence, predisposing them to a more hazardous trajectory of college alcohol use. Characteristics of low extraversion may afford some protection from alcohol-positive college culture. High neuroticism appears associated with a hazardous trajectory of college alcohol use, but continued research into situational factors of alcohol use in high neuroticism is warranted.

Sex-specific microhabitat use is associated with sex-biased thermal physiology in Anolis lizards.

If fitness optima for a given trait differ between males and females in a population, sexual dimorphism may evolve. Sex-biased trait variation may affect patterns of habitat use, and if the microhabitats used by each sex have dissimilar microclimates, this can drive sex-specific selection on thermal physiology. Nevertheless, tests of differences between the sexes in thermal physiology are uncommon, and studies linking these differences to microhabitat use or behavior are even rarer. We examined microhabitat use and thermal physiology in two ectothermic congeners that are ecologically similar but differ in their degree of sexual size dimorphism. Brown anoles (Anolis sagrei) exhibit male-biased sexual size dimorphism and live in thermally heterogeneous habitats, whereas slender anoles (Anolis apletophallus) are sexually monomorphic in body size and live in thermally homogeneous habitats. We hypothesized that differences in habitat use between the sexes would drive sexual divergence in thermal physiology in brown anoles, but not slender anoles, because male and female brown anoles may be exposed to divergent microclimates. We found that male and female brown anoles, but not slender anoles, used perches with different thermal characteristics and were sexually dimorphic in thermal tolerance traits. However, field-active body temperatures and behavior in a laboratory thermal arena did not differ between females and males in either species. Our results suggest that sexual dimorphism in thermal physiology can arise from phenotypic plasticity or sex-specific selection on traits that are linked to thermal tolerance, rather than from direct effects of thermal environments experienced by males and females.