The use marker alleles for the introgression of linked quantitative alleles.

It is shown that when an exotic strain and a commercial strain differ genetically at a quantitative locus and at an adjoining marker locus, repeated backcrosses to the commercial strain, retaining only backcross progeny carrying the exotic marker allele, will allow the effective introgression of the linked quantitative allele from the exotic to the commercial strain. The introgression procedure will be particularly effective when exotic and commercial strains differ at two nearby marker loci with the quantitative locus bracketed between them. The simultaneous introgression of a number of quantitative alleles from different exotic strains, and appropriate selection procedures in the intercross generations that follow are also considered.

Genetic aspects of the transition from traditional to modern fish farming.

A theoretical model describing the genetic aspect of the transition from traditional to modern animal husbandry is presented. Traditional races are characterized by high tolerance to harsh environments but a low rate of response to increased management inputs. Modern, artificially-selected breeds are efficient convertors of management inputs to higher production but have a low resistance to harsh environments.

Familial differences in antibody response of broiler chickens to vaccination with attenuated and inactivated Newcastle disease virus vaccine.

Genetic differences in immune response to Newcastle disease virus (NDV) were studied in 4-week-old broilers, vaccinated with attenuated (live) or inactivated NDV. The experiment included 370 chicks from two farms distributed among 22 sire families and 60 dam families. Results in chicks from both farms were similar.

On the power of experimental designs for the detection of linkage between marker loci and quantitative loci in crosses between inbred lines.

The power of experiments aimed at detecting linkage between a quantitative locus and a marker locus, both segregating in the backross or F2 generation of a cross between two inbred lines, is examined. Given that the two lines are close to fixation for alternative alleles of both marker locus and quantitative locus, it is concluded that experiments involving a few thousand offspring should be able to detect close linkages involving quantitative loci (or groups of loci) having rather modest effects (i.e.

Genetic and environmental correlations between brain weight and maze learning in inbred strains of mice and their F1 hybrids.

The relationships among body weight, cerebellum weight, cerebrum weight, maze-learning ability in a double T-maze, and discrimination learning in a Y-maze were studied in six inbred strains of mice and some of their F1 hybrids. The subjects were 131 male albino mice from 14 genotypic groups: five inbred groups and nine groups of crossbred offspring. Intra- and intergroup correlations were computed between all possible pairs of the anatomical and behavioral traits.

A note on assortative mating and artificial selection.

A simple method is presented for determining the effect on the genetic variance of a quantitative trait, of selection followed by various degrees of assortative mating.