Showing papers in "Behavior Genetics in 1985"

Multiple Regression Analysis of Twin Data

Abstract: A multiple regression model for the analysis of twin data is described in which a cotwin's score is predicted from a proband's score and the coefficient of relationship (R=1.0 and 0.5 for identical and fraternal twin pairs, respectively). This model is especially appropriate for the analysis of data on twins in which one member of each pair has been selected because of a deviant score, e.g., low reading performance. When the model is fitted to such data, the partial regression of the cotwin's score on the coefficient of relationship provides a powerful test of the extent to which the difference between the mean for probands and that for the unselected population is heritable, i.e., a test for genetic etiology. By fitting an augmented model containing an interaction term to either selected or unselected data sets, direct estimates of heritability and the proportion of variance due to shared environmental influences can also be obtained (subject, of course, to the usual assumptions underlying twin analyses, e.g., a linear polygenic model, little or no assortative mating, and equal shared environmental influences for identical and fraternal twins).

The resolution of cultural and biological inheritance: Informativeness of different relationships.

Abstract: The informativeness of different relationships for resolving the genetic and cultural transmission of a continuous variable is explored by computer simulation. Extended twin, extended nuclear-family, and adoption designs are considered. Combining data on twin and parent-offspring pairs provides a powerful means of detecting genetic and cultural transmission. The addition of uncle-nephew and first-cousin data sometimes leads to an increase in power. Designs involving monozygotic twin pairs and their offspring are weaker. The most powerful adoption designs involve data on both biological parent-adopted-away offspring and adoptive parent-adopted offspring pairs. In the absence of information about biological parents, combining nuclear-family, adoptive parent-adopted offspring, and adoptive/natural sibling relationships still provides a powerful strategy for hypothesis testing. Adoption designs are more robust than extended twin and extended nuclear-family designs for resolving cultural and biological inheritance in the presence of genetic dominance or phenotypic assortative mating.

A twin study of ethanol metabolism.

Abstract: Blood alcohol measurements were obtained for 206 pairs of twins who had ingested a standard dose of alcohol (0.75 g/kg body weight) and repeat measurements were obtained for 40 of these pairs on a second occasion. The repeatability of the peak blood alcohol concentration (BAC) was 0.66, that of the rate of elimination was 0.39, and that of the time to peak BAC was 0.27. Only a small portion of the nonrepeatable variance could be explained by measurement error or drinking experience. It is concluded that short-term environmental factors exercise considerable influence on alcohol metabolism, particularly in the absorption phase. All of the repeatable variance in peak BAC and rate of elimination was due to genetic factors. Only a small proportion of any of the genetic variance could be explained by individual differences in weight, adiposity, or lung function. Likewise, these three factors were unable to account for the fact that females had higher BACs than males during both absorption and elimination.

Bidirectional selection for susceptibility to ethanol withdrawal seizures in Mus musculus.

Abstract: Using within-family selection from a genetically heterogeneous population of HS/Ibg mice, lines and replicates have been selected for high (withdrawal seizure prone; WSP) and low (withdrawal seizure resistant; WSR) susceptibility to convulsions after withdrawal from chronic exposure to ethanol. Two nonselected control lines (withdrawal-seizure control; WSC) have also been maintained. The response was bidirectional in both replicates across 11 selected generations, WSP and WSR lines differing approximately 10-fold in seizure severity after an identical regimen of chronic exposure to ethanol. Realized heritability was found to be approximately 0.28. The phenotype appears to be polygenic in nature. The relatively low amount of inbreeding in these lines and the large response to selection should make them useful for examining the physiological basis of physical dependence on ethanol.

Resolving the effects of phenotype and social background on mate selection.

Abstract: Traditional studies of mate selection have not addressed the question of how a marital correlation arises. The common assumption that assortative mating is based on phenotype has not been properly tested. Social background may be a major determinant of choice of spouse. We show how the collection of data on monozygotic (MZ) and dizygotic (DZ) twin pairs and their spouses, and estimation of all possible correlations between the twin pairs and their spouses, will allow these alternative hypotheses to be tested. Power simulations show that it will be feasible to resolve the contributions of phenotype and social background to mate selection for variables such as IQ, education, and attitudes for which the marital correlation is moderately high.

A twin study of psychomotor and physiological responses to an acute dose of alcohol.

Abstract: A battery of psychomotor tasks and physiological measures was administered to 206 pairs of twins before alcohol and then three times at hourly intervals after they ingested a standard dose of ethanol (0.75 g/kg body weight). Repeat measurements were obtained for 41 of these pairs on a second occasion. Performance on motor coordination, standing steadiness, pursuit rotor, arithmetic computation, and reaction-time tasks deteriorated after alcohol, but decrements on the five tasks were generally independent of each other. Measurements of blood pressure, pulse rate, and skin temperature were all elevated following alcohol intake, but these responses were also uncorrelated. The variance in many of these measures increased after alcohol. An analysis of covariance structure revealed that most of this additional variance exposed by alcohol was genetic in origin, particularly for standing steadiness, pursuit rotor, arithmetic computation, and pulse rate. Up to 50% of the variance in body sway after alcohol was estimated to be due to genetic factors expressed only under the influence of alcohol. Although significant correlations were found with blood alcohol concentration, previous drinking experience, and the personality trait Extraversion, little of the genetic variance exposed by alcohol could be explained by these predictors. It is concluded that the sources of the considerable genetic variation affecting performance under alcohol must be sought elsewhere.

Gene mapping studies with the syndrome of autism.

Abstract: The UCLA Registry for Genetic Studies of Autism had collected data on 308 families by February 1, 1983. A subsample of 46 families withat least two affected children was analyzed for evidence of a Mendelian mode of inheritance. The data were consistent with an autosomal recessive mode of inheritance (Ritvo, E. R., Spence, M. A., Freeman, B. J. Mason-Brothers, A., Mo. A., and Marazita, M. L., 1985, American Journal of Psychiatry, in press). Thirty-four of these families were subjected to gene linkage analyses with 30 standard phenotypic gene markers. There is no evidence of linkage between the purported autism locus and HLA, either from analysis of HLA haplotype sharing or fromlod scores. In addition, close linkage with autism, i.e., ≤5% recombination, could be excluded for 19 of the other autosomal genetic markers. The largest positivelod score, 1.04, was with haptoglobin (HP), at recombination frequencies of 10% in males and 50% in females. Normal C-and Q-banded chromosome polymorphisms were evaluated for association with autism and as additional linkage markers.

A multivariate analysis of the genetics of fearfulness in potential guide dogs.

Abstract: Fearfulness is the most common reason causing dogs to be unsuitable for training as guide dogs We have carried out a diallel cross using four breeds of dog—Labrador, German shepherd, boxer, and kelpie—and recorded 38 measures of fearfulness The variation between litters was described by three discriminant functions One function, which measured general fearfulness, showed significant genetic variation but no nongenetic between-litter variation The other two functions showed a mixture of genetic and environmental variation Of the three functions, only general fearfulness affected a dog's suitability as a guide dog Labradors were the least fearful and German shepherd dogs the most fearful of the four breeds There was no heterosis for general fearfulness, but there was significant within-breed genetic variation, implying that fearfulness could best be reduced by a selection program among Labradors Optimum methods of selecting against general fearfulness are discussed

Comment on genetic similarity theory

Abstract: Genetic similarity theory, a purported extension of the concept of inclusive fitness, is not only unnecessary, but also logically flawed. In this paper, the author (1) discusses the definition of inclusive fitness; (2) identifies the major logical flaw of genetic similarity theory; and (3) refers readers to earlier, more thorough discussions of several common mis-understandings of kin selection and assortment.

Female discrimination of male odors correlated with male genotype at the T locus: a response to T-locus or H-2-locus variability?

Abstract: Female house mice (Mus musculus), derived from several populations of wild-caught mice, were tested for their ability to discriminate between males whose genotype at the T locus was +/+ and those whose genotype was +/t, using odor cues alone. Females spent more time near the odors or +/+ males than near the odors of +/t males. This preference was independent of the T-locus genotype of the female and the particular type of t allele carried by either the male or the female. A female's preference, however, did appear to be related to the genotype of her parents. Females with one +/t parent were more likely to prefer +/t males than were females whose parents were both +/+. In a second experiment 18 females were tested with odors from soiled bedding of recombinant males whose genotype varied at the T locus but who were similar at the H-2 locus. As a control, these 18 females were also tested with bedding of wild-derived +/+ and +/tw semilethal males. Females tested with recombinant males preferred odors of males not carrying lethal t alleles over those of males carrying two lethal t alleles, indicating that T-locus variability, not H-2-locus variability, is responsible for odor differences between +/+ and +/t males. Female responses to odors of recombinanat males did not differ from those to odors of +/+ and +/tw semilethal males. Responses of mice to odor differences associated with T-locus variability may have evolved independently of responses to odor variability associated with the H-2 locus.

The aging effect on male mating activity in Drosophila melanogaster.

Abstract: Noncompetitive mating activity for young (3-day) and old (28-day) Drosophila melanogaster males was measured under chromosomally homozygous and heterozygous conditions. Old males were consistently less active than young ones under both conditions. Three of 29 homozygous lines exhibited sterility due to aging. Virility at the old age did not correlate with that at the young age. Differences among homozygous lines were highly significant for old and young males, indicating a genetic basis for the trait. Individual variation in “old” virility was shown to be much higher than that in young males.

Genetic similarity theory: a reply to Mealey and new evidence.

Abstract: Mealey's criticisms of genetic similarity theory (GST) (Rushton,et al., 1984) are rebutted as either based on a misreading of its claims or a failure to grasp the nature of such theorizing. We argue that, if a gene can ensure its own survival by acting so as to bring about the reproduction of any organism in which copies of itself are to be found, then GST is a worthwhile alternative to kin selection theory. The most effective way for this to be accomplished is for organisms to be able to detect copies of its genes in others, and proffer preferential treatment to those most similar. We report novel data congruent with this hypothesis: (a) spouses assort more on the basis of the more genetically influenced of a set of homogeneous traits (i.e., there is a positive correlation between assortative mating coefficients and heritability estimates), and (b) following the death of a child, parental grief intensity is correlated with the child's similarity to the parent.

No decline in assortative mating for educational level.

Abstract: Education data from the Norwegian twin panel reveal no decline in the marital correlation for educational attainment for the past 35 years. Comparable marital correlations are found for British and American samples. A higher marital correlation is obtained for the parents of the Norwegian twins and the parents of their spouses, but this is an artifact. A twin's recall of his/her parents' educational levels is shown, by model fitting, to be biased by his/her own education level. Allowing for this bias reduces our estimate of the parental marital correlation and reduces estimates of the broad heritability of educational attainment from 74–81 to 49–58%. Other, unrelated factors may also be biasing estimates of the similarity of their parents' educational levels by the twins and their spouses.

Segregation analysis of human hand preference.

Abstract: Segregation analysis was performed on a large body of data on hand preference in nuclear families. The results suggest that the pattern of inheritance is consistent with Mendelian transmission, with different penetrance parameters for males and females. Although a single-locus model was more likely, a polygenic alternative could not be rejected. The parsimonious model specified a recessive right-shift gene of frequency 0.748. All females with the right-shift genotype become right-handed, while a small percentage (4.2%) of males with the right-shift genotype becomes left-handed (sporadic left-handers). Goodness-of-fit tests of simple genetic models were performed on the current data set as well as six others from the literature. Results suggest an adequate fit of both single-locus and polygenic models in nearly all data sets, with reasonable consistency among the parameter estimates. Furthermore, the observed generational effect in hand preference (reduction in left-handedness in parents compared with offspring) is found to be consistent with the relaxation of cultural pressure over time. Also, the simple genetic models of hand preference provide an acceptable alternative to maternal transmission, which has previously been suggested.

Morphometric studies in inbred and hybrid house mice. VI. A genetical analysis of brain and body size.

Abstract: Body size (weight) and brain size were measured in inbred and hybrid mice of three different ages (1, 3, and 5 months). Hybrid values were generally greater than those of either inbred parent for both characters at all three ages (overdominance). There was statistically significant positive heterosis for both brain and body size, its magnitude consistently averaging slightly over 1.0 standard deviation unit. The variance in inbred groups was significantly greater than in hybrid groups (positive homeostasis) for body size at 1 month and for brain size at 3 and 5 months. Both characters differed among inbred strains, crosses, reciprocals, litters, and litter sizes, although body size exhibited more sexual dimorphism than did brain size. Heritabilities for brain size were high (0.63–0.67) and consistent in all ages studied, whereas those for body size were moderate in magnitude (0.28–0.54) and increased with age.

Genetic polymorphisms and additive genetic models

Abstract: The degree of genetic dissimilarity between inbred strains or substrains of mice may be estimated from available data concerning biochemical and immunological polymorphisms. Dissimilarities between substrains are bimodally distributed, suggesting that both genetic drift and contamination are responsible for substrain differences. Previously published data concerning open-field activity in a number of inbred strains are analyzed with a view to showing a linear dependence of behavioral differences on genetic dissimilarity; two independent sources of data show that about 13% of the variance may be thus explained, and that additional information explaining a further 6–11% is gained by taking into account the effects of albinism. These results are in moderately good agreement with the results of more conventional biometrical analyses.

Heritability estimate for temperament scores in German shepherd dogs and its genetic correlation with hip dysplasia.

Abstract: Temperament and hip dysplasia scores of 575 German shepherd dogs bred and evaluated by the United States Army's Division of Bio-Sensor Research between 1968 and 1976 were examined. The records represented 4 years, 18 sires, and 71 dams. Restricted maximum-likelihood procedures were used to obtain variance component estimates from which the heritabilities and genetic correlation were estimated. Heritability estimates for the temperament and hip dysplasia scores were 0.51 and 0.26, respectively. The genetic correlation between the two traits was estimated as −0.33. Males showed significantly higher temperament scores than females.

Experience-mediated courtship reduction and competition for mates by maleDrosophila melanogaster

Abstract: Previous research has described conditions which will alter the mating behavior of femaleDrosophila. MaleD. melanogaster exposed to mated females or immature males will show reduced levels of courtship toward normally attractive virgin females or immature males, respectively. Experiments allowing experienced and naive subject males to compete for virgin females are described. The results indicate that experience with mated females does not significantly alter the effectiveness of a male competing for a mate. However, experience with immature males can significantly increase the chances of securing a mate in some circumstances. These results are consistent with previous suggestions that “learning” phenotypes inD. melanogaster may be associated with evolutionary fitness.

Behavior-genetic analysis of the paradise fish, Macropodus opercularis. I: Characterization of the behavioral responses of inbred strains in novel environments: a factor analysis

Abstract: Behavioral responses to novelty of female paradise fish were investigated. Individuals of four pure-breeding strains and an outbred population were compared in a variety of standard behavioral tests. An ethological description of the same subjects was obtained by recording time sequences of defined behavior elements. Results on standard psychological tests were related to ethologically defined behavioral units by factor analysis.

Relation between the genetic variability of digging behavior of Drosophila larvae and their susceptibility to a parasitic wasp.

Abstract: TwoDrosophila strains were compared with respect to the behavior of their larvae on food substrate: a wild-type strain (D) from the West Indies exhibited digging behavior, while a laboratory strain (S), bearing theebony mutation, remained on the surface. Chromosome transfers showed this difference to be due mainly to autosomes. There was a significant difference between the two strains in the proportions of larvae parasitized by a cynipid wasp. This was not due to theebony mutation or to other traits such as larval size, cuticle thickness, and speed of development. Chromosome transfers demonstrated a significant role of the three major chromosomes in the susceptibility to the parasite. A clear parallelism was found between the susceptibility to parasitization and the proportion of surface larvae. The depth of concealment of the larvae in the food matter appears to be a favorable behavioral strategy for escaping parasite attacks. The possible adaptive significance of genetic variations in larval behavior is discussed.

Genetic stability of cannibalism in Tribolium confusum.

Abstract: This study reports the stability of genetically controlled cannibalistic behavior in four strains of flour beetles. The strains were derived from Thomas Park's “Chicago Standard” strain ofTribolium confusum using only three or four generations of brother-sister matings in the mid-1950s. Their cannibalistic attributes, as well as their fecundity, egg hatchability, developmental time, and adult longevity, were assayed shortly thereafter and strong interstrain cannibalistic differences were reported. However, other aspects of their demography were remarkably similar. Using the same strains, the cannibalism assays, originally performed during 1959–1962, were repeated. After some 60 generations of husbandry in identical abiotic environments, the strains are essentially unchanged. Different environments were generated, however, by the social and antisocial behaviors of the beetles themselves. The stability is discussed with regard to three possibilities: (1) there are only a few genes which account for the observed differences in cannibalism, (2) cannibalism is selectively neutral, and (3) each strain is at a different local adaptive peak with respect to cannibalism.

Prepupation behavior in Drosophila: embedding.

Abstract: A newD. Melanogaster prepupation behavior, “embedding,” is described. Prior to pupation, some larvae burrow through the agar and pupate at the end of the burrowed tunnel with the posterior end of their body embedded in the agar. Embedding behavior is studied in laboratory-and field-derived stocks under two light regimes and in two test dishes. The chromosomal constitution of the strains (in particular the third pair of autosomes) significantly affected differences in embedding behavior. Differences in embedding behavior were also affected by light regime but not by test dish.

Fitting heredity-environment models jointly to twin and adoption data from the California Psychological Inventory.

Abstract: A method is proposed for fitting heredity-environment models simultaneously to data from several groups on multiple measures. The procedure is shown to be computationally practicable by applying it to the 18-scale California Psychological Inventory (CPI), using data from 17 subgroups from two twin studies and an adoption study. A number of models involving different assumptions about heredity and environment were tested. Overall, the genes appeared to contribute about 40% of the personality test variance; shared family environment, 5% or less; and other factors, presumably including idiosyncratic experiences, gene-environment interaction, and measurement error, the remaining 55%. On the whole, making distinctions among genetic parameters improved the fits of models more often than did making distinctions among environmental parameters, and models that allowed for differences across traits fit significantly better than models that did not.

Separated fraternal twins: resemblance for cognitive abilities.

Abstract: Thirty-four pairs of Swedish fraternal twins separated in the first 10 years of life were administered 12 tests of cognitive abilities. The average age of the twins was 59 years. Nineteen pairs were separeted before the first year of life and 26 pairs (76%) were separated by the age of 5 years. Moderate positive twin correlations were found for all tests, reaching significance for Raven's Progressive Matrices and Word Beginnings and Endings. A twin correlation of 0.52 emerged for the first principal component (a measure of general ability). Moderate correlations were found for Spatial Ability and for Verbal Ability/Perceptual Speed factors; for the Memory factor the correlation was lower. The effect of early environment on cognitive ability was assessed by analyzing the association between a degree of separation index and twin resemblance. The importance of the separation measures taken individually was also examined. Some significant effects were found, but these were consistently in a counterintuitive direction: Twins separated earlier weremore similar than those separated later.

Responses of male mice to odors of females: effects of T- and H-2-locus genotype.

Abstract: Male wild house mice (Mus musculus) were given a choice of odors of females whose T-locus genotype was +/ + or +/t Males showed strong preferences for the odors of +/ + females However, when males were tested with odors of recombinant females whose genotype differed at the T locus but which carried similar haplotypes at the H-2 locus, the preference for odors of +/+ females was not manifested Consequently, differences in female odor production that are responsible for male odor preference are not due specifically to the female genotype at the T locus

Genetic variation in the male courtship sound of Drosophila littoralis.

Abstract: Drosophila littoralis males and females emit sounds during courtship by vibrating their wings Genetic variation in the male courtship sound of this species was studied by analyzing the sounds of males of 42 fresh isofemale strains from three localities in Finland and those of several laboratory strains originating from Europe and Caucasus Among the fresh strains, the mean number of sound cycles in a pulse varied from 12 to 17 cycles, the length of a pulse from 39 to 51 ms, the length of a sound cycle from 29 to 36 ms, and the length of an interpulse interval (ipi) from 280 to 400 ms The sounds of the old laboratory strains differed from each other more than the sounds of the fresh strains There was, however, no sign of geographic differentiation

Long-term Ebony polymorphisms: a comparison of the contributions of behavioral and nonbehavioral fitness characters.

Abstract: Theebony11 mutant allele was observed to be polymorphic in three sets of duplicated populations which differed in their genetic backgrounds. The polymorphisms were maintained for over 5 years (130 generations) and showed no signs of decay, withebony frequencies fluctuating from 10 to 30%. Studies of fitness characters suggested that male mating speed may be an important factor in maintaining these polymorphisms, as heterozygous males mate significantly faster than either homozygote. Other characters such as female fecundity, larval viability, and developmental rate showed little evidence either for heterosis or for frequency-dependent effects which might contribute to the polymorphism.

Bivariate path analysis of familial resemblance for reading ability and symbol processing speed.

Abstract: A bivariate path model which incorporates measures of phenotypic assortative and cross-assortative mating is formulated for the analysis of familial resemblance for two characters in nuclear families (parents and at least one child). The model facilitates the partitioning of phenotypic variances for the two characters and their covariance into components due to transmissible familial (genetic and/or family environmental) influences and specific, nontransmissible environmental influences. The model is applied to the joint transmission of reading ability and symbol processing speed in families with a reading-disabled child and in those with children of normal reading ability. Although the model is not adequate to explain data on families with a reading-disabled child, it provides an acceptable fit to the data on control families, and parameter estimates obtained for the two data sets are very similar. Familial sources of variation are important for both reading ability and symbol processing speed, and more than half of the phenotypic correlation between the two variables is due to familial influences.

The genetic architecture of hyponeophagia and the action of diazepam in rats.

Abstract: Rats of 18 genotypes derived from the Roman selected strains were tested for inhibition of feeding due to novelty (hyponeophagia) in the absence or presence of 1 mg/kg diazepam. The resulting data from three behavioral indices were subjected to the Hayman [(1954). Biometrics10:235–244], variance/covariance, Mendelian cross, and single-test cross analyses. Additive genetic variation, directional dominance for high neophobia, and some nonallelic interaction were detected. The genetic architecture of the separate behavioral indices, and its modification in the drugged subjects, was discussed in relation to evolutionary adaptation and the anxiolytic and appetite-enhancing actions of the drug.

Larval behavioral response to environmental ethanol in relation to alcohol dehydrogenase activity level in Drosophila melanogaster.

Abstract: FourDrosophila melanogaster strains characterized by different alcohol dehydrogenase (ADH) activity levels are compared for the behavior of their larvae in response to environmental ethanol. The larvae are attracted by ethanol if they are able to convert rapidly the acetaldehyde resulting from the metabolic oxidation of ethanol. A comparison is made with the oviposition behavior of flies of the same strains in response to environmental ethanol. A similarity between oviposition behavior and larval behavior is found only for a strain lacking both alcohol dehydrogenase and aldehyde oxidase (AO).