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Biomedical subjects

B Wallace

Publications and source records attributed to B Wallace.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Evidence for social learning in the self-presentation of alcohol problems.

AIMS: To examine the extent to which problem alcohol users' self reports of drinking pattern and symptomatology derive primarily from a functional, learned social-cognitive schema (referred to as a 'script' in this paper), rather than from acts of recall or memory. METHODS: Using a between-groups design with one repeated (within-subjects) measure, problem drinkers and non-problem drinkers were asked to complete a questionnaire about drinking behaviour and symptoms. Each group filled in the questionnaire twice, under both of two conditions. In condition one, they used the questionnaire to describe their own drinking and in condition two they were asked to describe the drinking of the other group (i.e. the problem drinkers filled out the questionnaire to describe non-problem drinking and the non-problem drinkers described problem drinking). RESULTS: Using analyses of variance for the different sub-scales of the questionnaire, no overall differences were found between the two groups on four of the five subscales. However, clear and significant differences were found between the two conditions. That is, both groups were able to produce clearly differentiated scripts for both problem drinking and non-problem drinking. CONCLUSIONS: These data, together with related data from other sources, suggest that 'scripts' for problem drinking and for non-problem drinking can be elicited from both problem-drinking and non-problem-drinking groups. The data support conclusions from an earlier study, suggesting that subjects may use learned 'scripts' rather than recall when responding to certain types of questionnaire instruments.

Adult↗
PubMedDate not supplied

The Wilhelmine E. Key 1986 invitational lecture. Fifty years of genetic load.

The author's involvement with and his successive reactions to the genetic load concept [whose beginning is identified with Haldane's paper. The effect of variation on fitness] is presented in the form of a personal odyssey. The major change in attitude involved the realization that the density- and frequency-independent selection discussed by most population geneticists has little bearing on events transpiring within natural populations; instead, natural selection should be viewed primarily as a density- and frequency-dependent phenomenon. Under this view, the culling of a large number of young zygotes to the considerably smaller number of adults that can be sustained by the environment is an essential process enabling any population's continued existence; to the extent that genetic variation facilitates culling, a genetic load (in direct opposition to the early view) can enhance a population's persistence through time.

Animals↗
PubMedDate not supplied

Selection for the inviability of sterile hybrids.

Complementary lethal, semilethal, and dwarfing genes whose effects appear to be expressed only in (usually sterile) interspecific hybrids are not uncommon in plants. Accounting for these genes by Darwinian selection has been somewhat puzzling. However, if luxuriant, sterile hybrid progeny compete with and tend to eliminate their pure-species half-sibs, genes that are detrimental to the growth and development of hybrid progeny will be favored by Darwinian selection; the selective advantage lies in the improved fertility of parental plants. This account, which deals largely with the corky gene of New World cotton species, contrasts events that may occur in plant and animal species.

Alleles↗
PubMedDate not supplied

Coadaptation revisited.

During the four decades or more since Dobzhansky introduced the term "coadaptation" to refer to the commonly observed selective superiority of inversion heterozygotes in populations of Drosophila pseudoobscura, the definition of the term has evolved, as have views concerning the rapidity with which coadaptation might occur. Indeed, the paucity of demonstrated instances of linkage disequilibrium in natural populations has led many to dismiss coadaptation as a factor in evolutionary change. The present article reviews the reasons why coadaptation (and the equivalent expression, "integration of gene pools") was proposed as a phenomenon occurring in local (or experimental) populations, offers supporting data obtained through a reanalysis of data on irradiated populations of D. melanogaster, and concludes that sound evidence supports coadaptation as a factor in the genetic change of populations.

Adaptation, Biological↗
PubMedDate not supplied

On the displacement of single-locus polymorphisms.

And where, along the evolutionary track, some mutant gene did arise which was advantageous in its heterozygous degree of expression but deleterious homozygously, that gene, though temporarily multiplied as a make-shift arrangement, would usually have become replaced, after a while, by mutant genes of less deviant expression, occupying the same or other loci, which gave an equivalent advantage when they were present homozygously. For such genes would make possible a more uniform, and therefore (when all individuals were averaged) a closer approach to the adaptational optimum.

Alleles↗