Stability of a factor-analytic description of smoking behavior.

Three types of human smoking behavior, identified by factor analysis of questionnaire responses, were found to exhibit a stable structure in a series of different populations and environments. Type I smoking behavior is closely related to a personally perceived need for tobacco products. Types II and III are related to psychosocial-sensorimotor rewards and the intensification of pleasure, respectively. The typology is easily detectable and remarkably constant in the following populations: staff, employees, and patients of a teaching hospital in London, England; urbanites and suburbanites of mixed ages in a part of metropolitan Denver, Colorado, U.S.A.; college students in Fort Collins, Colorado, U.S.A., elderly urbanites and suburbanites in the metropolitan areas of (a) Stockholm, Sweden and (b) Göteborg, Sweden; and the adult children of the Swedish groups (a) and (b).

Response to Selection for Mating Speed and Changes in Gene Arrangement Frequencies in Descendants from a Single Population of DROSOPHILA PSEUDOOBSCURA.

Heritability estimates, based on 19 generations of selection for fast and slow mating speed, were not significantly different from zero at the 0.05 level in any replicate of selected lines in a population of flies descended from the Mather population in California. Only the combined heritability estimate of approximately 2% was significant. This indicated that very little additive genetic variance was present in the base population and that strong directional selection for rapid mating may have occurred in the previous history of the local population at Mather and/or during its many generations of laboratory propagation. Frequencies of third chromosome gene arrangements were monitored during the course of selection. Balancing selection, unrelated to that imposed for mating speed, and genetic drift appeared to be the major factors causing changes in chromosome frequencies. Present differences in adaptive value of third chromosome variants in nature may be associated with nonadditive effects on mating speed, as well as effects on other components of fitness.

Fertility and offspring survival in mice selected for different sensitivities to alcohol.

The LS (long-sleep) and SS (short-sleep) selected lines of mice exhibit relatively high and low sensitivity to alcohol, respectively, because of their previous history of selective breeding. The present study identifies other differences between the two lines. SS animals are almost twice as fertile as LS animals. Analysis of vaginal plug formation suggested that higher sexual activity of SS mice is an important component of their greater fertility. Forced maternal drinking of a 10% ethanol solution during gestation, and especially during lactation, caused a decrease in survival of LS but not of SS offspring. Increased cannibalism of pups by LS mothers was probably an important component of this decrease in progeny survival. Maternal consumption of liquid in both lines was decreased during gestation, and especially during lactation, when 10% ethanol was the only available liquid in each case. The physiological basis for decreased survival of LS progeny may involve either direct effects of alcohol on progeny or indirect effects caused by water, nutritional, or hormonal imbalance in LS mothers when they are exposed to alcohol stress. The relationship of fertility and progeny survival differences in the two lines to their differences in alcohol sensitivity produced by selective breeding is discussed.

Cold temperature resistance, chromosomal polymorphism and interpopulation heterosis in Drosophila pseudoobscura.

Descendants of two Colorado, U.S.A., populations of D. pseudoobscura, Boulder and La Foret, were exposed to +2 degrees and -2 degrees . In third instar larvae from Boulder AR and PP third chromosome gene arrangements survived better than TL and others, while the reverse situation occurred for La Foret. Deleterious dominant effects were observed for AR from La Foret. In adults from Boulder there was a trend towards greater survival for AR and PP than for other gene arrangements, while AR from La Foret showed relatively poor cold resistance. Survival of Boulder and La Foret flies, and their interpopulation hybrid, was determined after exposure to -2 degrees at two humidities. Order of survival of developmental stages was: adults >> third instar larvae > mixture of first and second instar larvae. Adults survived better at low humidity, while larvae survived better at high humidity. Boulder adults and larvae survived better than those from La Foret. Advantage in survival of hybrids over the midparent ranged from 23% to 138%. Hybrid advantage over the higher parent ranged from 5% to 111%. Order of expression of heterosis was: mixture of first and second instar larvae > third instar larvae > adults. Relation of all results to the chromosomal polymorphisms at Boulder (seasonally constant) and La Foret (seasonally cyclic) is discussed.