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Biomedical subjects

M Slatkin

Publications and source records attributed to M Slatkin.

77 records · Page 5Linked to original sources
PubMed1973

Gene flow and selection in a cline.

A model of the effect of gene flow and natural selection in a continuously distributed, infinite population is developed. Different patterns of spatial variation in selective pressures are considered, including a step change in the environment, a "pocket" in the environment and a periodically varying environment. Also, the problem of the effect of a geographic barrier to dispersal is analyzed. The results are: (1) there is a characteristic length scale of variation of gene frequencies, (see PDF). The population cannot respond to changes in environmental conditions which occur over a distance less than the characteristic length. The result does not depend either on the pattern of variation in selective pressures or on the exact shape of the dispersal function. (2) The reduction in the fitness of the heterozygote causes a cline in gene frequencies to become steeper. (3) A geographic barrier to dispersal causes a drastic change in the gene frequencies at the barrier only when almost all of the individuals trying to cross the barrier are stopped.

Environment↗
PubMed1972

On treating the chromosome as the unit of selection.

A simple method is presented for approximating the behavior of a multiple genetic system under the action of selection and linkage. The effects of genetic drift and mutation are left out. It is found that the results are close to those obtained from a computer simulation of the same problem by Franklin and Lewontin (1970). It is possible to describe the system in terms of a correlation length on the chromosome which measures the degree to which the different parts are bound by linkage. There is also a brief discussion about the higher order correlation coefficients as a measure of the interaction effects.

Alleles↗
PubMed1970

Selection and polygenic characters.

A mathematical model is developed which describes the effect of selection on polygenic or continuously varying phenotypic characters. For the simplest case the standard deviation of a phenotypic character in a population cannot be greater than radical2beta where beta is the expected deviation of the offspring from the average of the parents' types. This is found to carry over to density-dependent selection, and it indicates that there are limits to the amount of phenotypic diversity, and therefore niche breadth, which a population can maintain. These limits, however, are also subject to selection.

Genetics, Population↗