Showing papers in "Behavior Genetics in 1987"

Recruitment bias in twin research: the rule of two-thirds reconsidered.

Abstract: A review of recent studies of adult volunteer twins confirms an earlier report that, in such studies, male and dizygotic twin pairs are underre-presented. The Martin and Wilson [(1982). Behav. Genet.12:467–472] model of recruitment bias assumes that individuals who are twins respond to recruitment in the same way that singletons do. It is argued that twins recruited for twin studies may be influenced by additional factors, and evidence in support of this view is presented. The consequences of the augmented model. illustrated by Monte Carlo methods, suggests the following conclusions: (1) recruitment bias can have unpredictable and sometimes large effects in the form of under- or, more likely, overestimation of the true twin correlations; (2) these effects will tend to be larger among dizygotic, than among monozygotic, twins; and (3) differential recruitment bias is likely to be accompanied by monozygotic (MZ): dizygotic (DZ) differences in the total variance of the traits measured. Showing that the dependent variable has as large a variance in the twin sample as in the reference population, or that the means and variances of the MZ and DZ samples are similar, provides considerable reassurance that the sample statistics may be representative.

Circadian and ultradian rhythms in period mutants of Drosophila melanogaster.

Abstract: Using digital techniques for signal analysis—the correlogram and a high-resolution analysis of time series, maximum-entropy spectral analysis (MESA)—we have detected both circadian and ultradian rhythms in the locomotor activity of free-runningper 0 males and in females lacking theper locus (per −; heterozygous for two deficiencies, each of which deletes the gene). Over half theper 0 individuals and half theper − individuals tested were rhythmically active, with dominant periods ranging from 4 to 22 h; most of the significantly rhythmicper 0 andper − flies clearly exhibited multiple periodicities. This novel pattern of rhythmic behavior is thoroughly distinct from the wild-type pattern. One hypothesis suggested by our observations is that theper + gene products mediate the coupling of multiple ultradian oscillators to produce wild-type circadian rhythms.

The genetic analysis of repeated measures I: Simplex models

Abstract: The well-known simplex model is extended to a model that may be used for the genetic and environmental analysis of covariance structures. This "double" simplex structure can be specified as a LISREL model. It is shown that data which give rise to a simplex correlation structure, such as repeated-measures data, do not fit a factor-analysis model. The parameter estimation of the simplex model is illustrated with computersimulated twin data.

Physical attractiveness and the personality resemblance of identical twins.

Abstract: The physical attractiveness of 25 pairs of monozygotic (MZ) twins was rated independently for twins A and B. The MZ twins were rated alike in their physical attractiveness (r=0.54; corrected for attenuation,r=0.94). Physical attractiveness was uncorrelated with verbal intelligence but was associated, controlling statistically for the sex difference in attractiveness favoring females, with three of the eight traits in the Comrey inventory: Conformity, Extraversion, and Emotional Stability. In both sexes, greater emotional stability was associated with attractiveness; in males greater extraversion; and in females, greater conformity. When these twin correlations were adjusted for this association with attractiveness, the mean change in the value ofr was only 0.03, indicating that physical attractiveness does not appear to bias conclusions from twin studies.

Performances of inbred and outbred laboratory mice in putative tests of aggression.

Abstract: A variety of situations commonly used to assess aggression in laboratory rodents was studied in two outbred varieties and six inbred strains of mice. The situations investigated included attacks on anosmic TO-line standard opponents by males from individual housing, from pairings with females, or after exposure to electroshock. Lactating females were studied in similar tests. Locust killing (predatory aggression) and restraint-induced target biting were also studied in male subjects. Cohabitation with females was generally a less effective means of inducing social conflict that individual housing. Maternal aggression was absent in some lines but was characteristic of genotypes with the most aggressive males. Correlations performed between the different tests of aggression (based on a combined score reflecting incidenceand intensity data) confirmed earlier claims that locust killing and target biting are distinct from intraspecific forms of attack. These data caution against ready extrapolation between different tests.

Mouse strain differences in operant self-administration of ethanol.

Abstract: By the use of operant conditioning procedures, we determined whether mice from two strains, C57BL/6J and BALB/cJ, differ in ethanol-reinforced behavior. To establish ethanol as a reinforcer, drinking was induced by feeding mice prior to the 30-min experimental session. Initially mice received water and then a series of increasing ethanol concentrations (1, 2, 4, and 8%, w/v) in response to a lever press. The volume of liquid consumed per unit of body weight remained relatively constant across concentrations, and thus the amount of ethanol consumed (g/kg) increased with increases in ethanol concentration. At all concentrations the C57BL/6J mice drank larger volumes than the BALB/cJ mice. After shifting the time of feeding from before to after the session, the consumption of 8% ethanol declined 56% for the C57B/6J mice and 81% for the BALB/cJ mice. To determine if ethanol was serving as a reinforcer, behavior and intake were then compared during ethanol and water availability. The ethanol consumption of the C57BL/6J mice markedly exceeded the water consumption and resulted in blood ethanol levels of 199 ±27 mg/dl. These levels significantly exceeded the 8% ethanol intake of the BALB/cJ mice, while 0% intake was low and not significantly different between strains. The 8% ethanol drinking of the BALB/cJ mice did not differ from their water drinking. Thus, ethanol was established as a positive reinforcer for C57BL/6J mice but not for BALB/cJ mice.

A reply to Heath et al. On assortative mating for educational level.

Abstract: Heathet al. (Behav. Genet.15:349–369, 1985), using data from a Norwegian twin registry and selected British and American samples, contend that assortative mating for educational level has not declined over the past 35 years. This is in contrast to the findings of Johnsonet al. Behav. Genet.10:1–8, 1980), who reviewed the assortative mating literature, and Ahernet al. (Behav. Genet.13:95–98, 1983), who analyzed data from the Hawaii Family Study of Cognition (HFSC). These authors found a decline in assortative mating for both intelligence and education. Heath and coworkers' criticism of the reliability of HFSC measures is rebutted, then new analyses are presented to show that the decline in assortative mating for both itelligence and education can be detected in self-report data from HFSC parents of Japanese ancestry, although not for parents of Caucasian ancestry. Data from a large-scale survey of alcohol use in Hawaii also indicate a decline in assortative mating for education. The differences in secular changes in assortative mating for educational level in Norway and in Hawaii appear to be real, not artifacts of measurement.

Asymmetry of a-b ridge count and behavioral discordance of monozygotic twins

Abstract: Nondirectional asymmetry of paired morphological structures may reflect a decrease in developmental buffering, thereby increasing susceptibility to developmental noise. The palmara-b ridge count, measuring the size of the second interdigital area of the hand, yields a convenient and promising index of developmental canalization in normal adults. We constrasted 28 monozygotic twin pairs in which one or both members exhibiteda-b ridge-count asymmetry, with 32 paris exhibiting little or no left-right asymmetry. The asymmetric paris were significantly less similar for many Minnesota Multiphasic Personality Inventory (MMPI) scales, and total variances of these scales tended to be greater among individual twins with extreme left-right asymmetries. The results suggest that an asymmetrica-b ridge count may identify individuals who are poorly buffered from developmental noise. But the asymmetry may arise from the twinning process itself, and our buffering hypothesis remains to be tested in twins of known placental type and in longitudinal instability of asymmetric nontwins.

Genetic and environmental factors in primary dysmenorrhea and its relationship to anxiety, depression, and neuroticism.

Abstract: Over 1200 pairs of female monozygotic and dizygotic twins with regular menses reported on the amount of flow, severity of pain, and degree of limitation experienced during menstruation. Fifty-two percent of the women reported moderate or severe menstrual pain and these reports were fairly repeatable (0.62–0.80) over a 3-month interval. Heritabilities were 0.22 for flow, 0.38 for pain, and 0.36 for limitation. Covariations between menstrual symptoms and the symptoms and personality variables of state anxiety and depression and trait neuroticism were shown to be almost entirely genetic in origin. There was also gene action specifically affecting menstrual pain and also menstrual flow, but genetic variation in limitation was entirely due to genes also affecting flow, pain, and personality variables-neuroticism in particular.

Genetic influences on ultrasonic vocalizations in young mice

Abstract: Ultrasonic calls produced by young mice elicit maternal investigation and retrieval, and their characteristics have been shown to vary with age and genotype. In this study, we completed a full Mendelian cross of two inbred strains BALB/cJ and DBA/2J. The major result was the detection of directional dominance for a high rate of calling. Other characteristics were influenced by additive and maternal effects in the absence of directional dominance. We estimate the number of loci involved in the rate of calling to be about 1—facilitating studies of a gene-to-behavior pathway.

Genotype-environment correlation and IQ.

Abstract: The estimation of various forms of genotype-environment (GE) correlation is considered. Two methods of estimating “passive” GE correlation from adoption studies are presented and illustrated with IQ data from five adoption studies. One method involves comparison of variances in adoptive and nonadoptive families, whereas the other compares parent-child correlations in such families. The second method yields more precise results for given sample sizes. Ignoring measurement errors leads to marked underestimation of GE correlations. Application of these methods to available adoption data on IQ suggests that typical passive GE correlations for IQ lie in the neighborhood of 0.30.

Locomotor activity in the Tyr-1 mutant of Drosophila melanogaster.

Abstract: The genetics and neurochemistry of locomotor activity inDrosophila have received increasing attention, although no precise relationship has been formulated, and researchers have not always distinguished the various forms of activity. In the present research, using the dopamine-deficientTyr-1 mutant, we demonstrate that it is possible to operationally define and provide separate measures of spontaneous activity and reactivity and have also isolated a third, distinct, category of locomotor activity which we term “stimulated” activity. Our data indicate thatTyr-1 mutants do not differ from isogenic wild-type flies with respect to spontaneous activity or reactivity but that they do display significantly higher stimulated activity levels. It is suggested that low levels of dopamine inTyr-1 may result in increased stimulated activity rather than spontaneous activity as previous research has suggested.

Mother-offspring interaction and pup development in genetically deaf mice.

Abstract: The role of ultrasonic calls emitted by pups on maternal behavior has been investigated by using genetically deaf (dn/dn) and normal-hearing (+/+) mice of the GFF strain. The behavior and the sensory-motor development of unfostered and cross-fostered pups, as well as the behavior of the mothers, was analyzed. Deaf pups emitted fewer ultrasonic calls than pups with normal hearing. The cross-fostering procedure decreased the amount of vocalizations produced by normal pups, thus stressing the reinforcement effect of maternal behavior on pups' ultrasonic communication. No difference in maternal behavior emerged between deaf and normal-hearing mothers toward their pups. However, cross-fostered pups received less maternal care than pups raised by their natural mothers, this effect being more evident in deaf pups reared by mothers with normal hearing, than vice versa. Deafness, in both mothers and pups, seemed to be associated with increased locomotor activity, possibly to offset their auditory handicap in mother-offspring relationships. Furthermore, deaf pups showed a faster gain in weight than normal pups, this capability being affected by the genotype of the rearing parent. On the whole, these data could suggest that maternal behavior in deaf mice has became independent of ultrasonic stimuli emitted by the pups. Other biobehavioral characteristics of deaf mice indicate a more active role played by these pups in mother-offspring interaction in comparison with pups with normal hearing.

Social inequality and assortative mating: cause or consequence?

Abstract: Johnsonet al. (Behav. Genet. 17:1–7, 1987) have interpreted an apparent decline in assortative mating for educational attainment in Hawaii as being a consequence of increased social mobility and increased access to higher education. Data on the educational attainments of adult twin pairs and their spouses from the Virginia twin registry are reported which give no indication of a major decline in the intensity of assortative mating. A previous study of a Norwegian population (Heathet al., Behav. Genet. 15:349–369, 1985), in which an increase in equality of educational opportunity had been documented (Heathet al., Nature 314:734–736, 1985), observed remarkable constancy of the marital correlation for educational attainment. There is thus little evidence that decreases in social inequality in a society lead to a decline in assortative mating.

Genetic analysis of circadian and ultradian locomotor activity rhythms in laboratory rats

Abstract: Obvious differences exist in the daily activity patterns of the LEW/Ztm and ACI/Ztm inbred strains of laboratory rats. The inbred strain ACI/Ztm shows a clear 24-h rhythm of locomotor activity. The activity pattern of the LEW/Ztm strain, however, is characterized by ultradian rhythms of 4- and 4.8-h periods. Genetic analysis of crosses between the two strains was used to examine the relative amounts of additive genetic and dominance effects for traits associated with circadian and ultradian rhythms of locomotor activity. The measured variables of the timing mechanism (amplitude c; acrophase φ; 24, 4.8-, and 4-h spectral estimates) exhibited substantial heritability, with general dominant-recessive modes of inheritance and the associated dominance variance.

Genetic control of the search tactic of Drosophila melanogaster: an ethometric analysis of rover/sitter traits in adult flies.

Abstract: Adults ofrover andsitter Drosophila melanogaster morphs, the larvae of which were previously shown to differ in their foraging tactics by Sokolowski [(1980).Behav. Genet. 10:291–302], can be discriminated as individuals with relatively straight paths (rovers) and restricted, intensive search paths (sitters). The larval progeny ofrover andsitter adult-selected lines, selected from a population of field-collectedD. melanogaster, had respectiverover andsitter larval traits, indicating a possible pleiotropic effect of genes on adult and larval searching behavior. Analysis of the temporal characteristics of the search tactics of adultrover andsitter morphs shows that the main differences between the two morphs are (1) the initial effect of feeding on locomotory rate, (2) the rate of the transition from intensive local search toward relatively straight foraging paths typical of unfed flies, and (3) the tendency to stop during searching. These movement parameters result in restricted, intensive search paths ofsitters and relatively straight paths ofrovers.

The genetic analysis of repeated measures II: The Karhunen-Loeve expansion.

Abstract: A new approach to the genetic analysis of time series of arbitrary length and with arbitrary covariance function is outlined. This approach is based on the simultaneous eigenvalue decomposition of the covariance matrices of the original time series obtained from monozygotic (MZ) and dizygotic (DZ) twins. The method is illustrated with computer-simulated twin data.

Pupation height in Drosophila: sex differences and influence of larval developmental time.

Abstract: Several lines ofDrosophila simulans andD. melanogaster of different origin were examined for pupation height. In all lines male larvae pupated, on average, higher than females. The pupation heights of early-, intermediate-, and late-pupating larvae were also recorded. As pupation progressed in the vials, larvae tended to pupate lower and lower, possibly as a response to diminishing levels of humidity inside the vials, which suggests a strong negative correlation between larval developmental time and pupation height. Thus, selection experiments for pupation height may also select for developmental rate. Since females generally pupate later than males, larval sex differences in pupation height may reflect sex differences in duration of development. The joint effects of sex and duration of development upon pupation height are discussed in relation to the lack of response previously reported in some experiments selecting for pupation height.

The ontogeny of sex appeal in Drosophila melanogaster males.

Abstract: Drosophila melanogaster males are sexually attractive when they are young, but they elicit very little courtship when they are 2–3 days old We have shown that males from a Canton-S stock start to lose their sex appeal between 3 and 4 h after they eclose from their pupal cases because they have begun to synthesizecis-vaccenyl acetate, an inhibitory pheromone, by that time Later, when the young males are between 20 and 24 h old, mature males perform even less courtship because the young males have begun to produce less of a courtship-stimulating pheromone

Phenotypic assortative mating vs. Social homogamy among Japanese and Chinese parents in the Hawaii family study of cognition

Abstract: Among the subjects of Japanese and Chinese ancestries in the parent generation in the Hawaii Family Study of Cognition were 47 pairs of siblings. Since data were available on the spouses of these siblings, this allowed for tests of whether spouse correlations of educational and occupational attainment and cognitive abilities were due to active phenotypic assortment and/or shared social background (social homogamy). Comparisons of sibling correlations, spouse correlations, and correlations between the spouse of one sibling and the spouse of the other sibling, as well as the results of model-fitting analyses, suggest that spouse correlations for education are determined by both phenotypic assortment and social homogamy, spouse correlations for occupational attainment by phenotypic assortment, and spouse correlations for verbal ability mostly by social homogamy.

Spouse similarities in personality items: changes over years of marriage and implications for mate selection.

Abstract: This study examines the variation in similarity between spouses in personality, as assessed by selected items of the Comrey Personality Scales (CPS), over 22 years of marriage. The sample consisted of 138 professional couples in Jerusalem. An analysis of 57 CPS items showed mild convergence for five out of the seven Comrey dimensions over the marriage span investigated and divergence for one Comrey dimension. Convergence and divergence were identified as reduction and increase, respectively, in extreme differences between spouses with length of marriage. These findings underline the necessity of considering the actual scattergrams with marriage length when dealing with assortative mating estimates, in addition to calculating correlation coefficients or comparing means over time. A detailed analysis of spouse correlations for Comrey items in the most recently married subgroup suggests possible mate selection for “self-other centeredness.” Implications for such selection are discussed.

Application of nonlinear factor analysis to genotype-environment interaction.

Abstract: The intention of this paper is to show how the methods of nonlinear factor analysis as developed by McDonal (Br. J. Math. Stat. Psychol.20:205–215, 1967) can be used to study genotype-environment interaction. The method is applied to the interaction of genotype and within-family environmental influences. Simulated twin data are used to illustrate how this type of interaction may be detected and estimated. It is shown that estimates of genetic influences are not affected byG×E interaction.

Adaptation to Daily Meal-Timing and Its Effect on Circadian Temperature Rhythms in Two Inbred Strains of Mice

Abstract: Inbred strains of mice differ in their adjustment to a mealtime out of phase with the light-dark cycle. When food access was restricted to the first 4 h of the light span, C3H/2Ibg mice steadily lost weight and died, while C57BL/6J mice recovered baseline levels of food intake within a few days. C57BL meal-timed mice also showed delayed circadian body temperature rhythms so that peak temperatures coincided with the time of food availability. Both strains were able to adapt when the period of food availability was gradually shifted to the first 12 h of the 16-h light period. C57BL mice again phase-delayed their body temperature rhythms, while C3H mice exhibited highly variable individual responses, and over half continued to increase temperature in anticipation of lights-off. These results suggest that the timing of body temperature rhythms of C57BL mice may be more easily altered relative to the light-dark cycle than that of C3H mice.

Characterization of genes involved with classical conditioning that produce differences between bidirectionally selected strains of the blow fly Phormia regina.

Abstract: Mean response levels for classically conditioned proboscis extensions in hybrid generations from a cross between bidirectionally selected strains of blow flies were used in a biometrical analysis. The best-fitting genetic model suggests the presence of additive, dominance, and digenic epistatic effects from at least four autosomal and X-linked genes. Neither maternal nor Y-linked effects were detected. Earlier studies have described the genetic and behavioral relations between the central excitatory state (CES) and classical conditioning. That evidence indicated that covariability of the two traits is produced by one autosomal gene. The results herein are consistent with such a hypothesis, and they explain why the CES—conditioning correlation is not perfect. Finally, knowledge that some genes associated with conditioning are located on the X chromosome and, therefore, are independent of the CES gene will facilitate efforts to identify new single genes affecting associative learning inPhormia.

Further evidence for a gene influencing spatial ability.

Abstract: Data for six spatial tests from 927 families of European ancestry, 369 families of Japanese ancestry, and 93 families of Chinese ancestry from the Hawaiian Family Study of Cognition were subjected to unified mixed-model segregation analysis. Father, mother, son, and daughter data sets from each ethnic group were separately age-adjusted and standardized and then separately subjected to transformation procedures to reduce skewness and kurtosis. Families were reassociated prior to segregation analysis. Evidence for a major gene contributing to spatial visualizing ability was obtained for Mental Rotations and Progressive Matrices even with a normalizing transformation which reduced skewness and kurtosis to zero. It was concluded that provision for testing deviation from Mendelian transmission in the unified model protected against false inference of a segregating major gene. Minimizing distributional differences in the components of a data set is an important pretreatment.

Testing genetic models for multiple symptoms: an application to the genetic analysis of liability to depression

Abstract: A model is presented which allows for the contribution of genes and environment to categorical data on multiple symptoms. The model distinguishes between parameters needed to express the relationship between a latent trait and observed responses and the parameters required to represent the causes of variation in the latent trait. The regression of the latent trait on covariates may also be specified. The model is applied to symptoms of depression in 1983 pairs of adult female monozygotic and dizygotic twins. A model which allows only for polygenic variation in the latent trait is supported as well as the "mixed model," which also allows for the effects of a major gene. The likelihood is significantly lower when all genetic effects are ascribed to a single gene. Practical limitations of the method are discussed.

Early development in mice. IV. Age at disappearance of the rooting response: genetic analysis in newborn mice.

Abstract: The experimentally induced rooting response can be elicited at birth in inbred strains of mice and disappears between 6 and 12 days of age. The age at disappearance of the rooting response (ADR) varies across strains. At 9 days of age, only 18% of C57BL/6By pups present the response, whereas 86% of BALB/cBy pups still exhibit it. Both the recombinant inbred strains method (using CXB stocks) and Mendelian crosses were used to analyze this difference. The results led to identical conclusions: early ADR is an incompletely dominant trait, correlated to one segragating unit, labeled Adre. Three independent techniques were used to map the new locus: the strain distribution pattern of the CXB recombinant strains, a comparison of the recombination proportion of Adre with previously mapped loci, and congenic strains. The findings are congruent and show that Adre is linked to brown (b), Mup-1, and the minor histocompatibility antigen locus H-21 on chromosome 4.

The effects of crowding on courtship and mating success in Drosophila melanogaster.

Abstract: The mating times of single males and pairs of males were increased by crowding with virgin females but only at very high densities. Mating times were decreased by the presence of a second male. Quantitative analysis of courtship showed that prestimulation of females in crowded conditions influences mating. The pattern of male courtship was highly consistent across moderate levels of crowding. This suggests thatDrosophila courtships evolved in crowded conditions.

The dynamics of sexual selection and its pleiotropic effects

Abstract: Since Darwin's formulation of the theory of sexual selection a number of population biologists have developed models that explore the genetic consequences of his theory. In all these models it is assumed that two forces act to counterbalance the runaway process of sexual selection. That is, female preference for a certain male character tends to select for extreme forms of that character until natural selection exerts its forces to maintain the optimum male phenotype that is able to survive in its environment. In this paper, an alternative explanation for the origin of secondary sexual characters is proposed. It is suggested that polymorphism in secondary sexual characters may be maintained not as a direct result of selection for these characters but by being either linked to or as pleiotropic effects of some other feature of the mate recognition pattern. While there are no genetic data to support these observations inDrosophila at this time, there appears to be compelling evidence that mating success is not wholly dependent on the presence of these characters.