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Biomedical subjects

M E Gilpin

Publications and source records attributed to M E Gilpin.

17 recordsLinked to original sources
PubMed1987

Neutral mutations and repetitive DNA.

We have previously shown that computer simulations of processes that generate selectively advantageous changes together with random duplications and deletions give rise to genomes with many different genes embedded in a large amount of dispensable DNA sequence. We now explore the consequences of neutral changes on the evolution of genomes. We follow the consequences of sequence divergences that are neutral when they occur in dispensable sequences or extra copies of genes present in multigene families. We find that when divergence occurs at about the same frequency as duplication/deletion events, genomes carry repetitive sequences in proportion to their size. Inspection of the genomes as they evolved showed that multigene families were generated by relatively recent duplications of single genes and so would be expected to be highly homogeneous.

Biological Evolution↗
PubMed1974

Gene frequency comparisons between taxa: support for the natural selection of protein polymorphisms.

The hypothesis has been advanced that the pervasive protein variation found in natural populations of many organisms is adaptively neutral, and thus not subject to natural selection. This neutrality hypothesis predicts that at polymorphic gene loci different configurations of allelic frequencies will occur in different species. Results of an extensive study of protein variation in several species of Drosophila show that any two species have very similar allelic frequencies at a substantial proportion of all gene loci, while at many other loci the species have very different sets of alleles. Genetic distances have been calculated between pairs of subspecies, morphologically similar species, and morphologically different species. The distribution of genetic distances is strikingly different from the predictions of the neutrality theory. Protein variation appears to be maintained by natural selection.

Alleles↗
PubMed1974

Interference competition and niche theory.

A linear model of interspecific competition with separate parameters for exploitation and interference is deduced. Interference is assumed to have a cost and an effect. The interfering species realizes a "profit" if some resources, which the species interfered against would have utilized, are made available as a result of the interference. Interference is favored when its cost is small, its effect is high, and the resource overlap with the species interfered against is high. Interference is likely to be an alternative strategy to high exploitation efficiency. The incorporation of interference into niche theory clarifies the competitive phenomenon of unstable equilibrium points, excess density compensation on islands, competitive avoidance by escape in time and space, the persistence of the "prudent predator," and the magnitude of the difference between the size of a species' fundamental niche and its realized niche.

Adaptation, Biological↗
PubMed1973

Global models of growth and competition.

Very precise data on the dynamics of a competitive system of two species of Drosophila have been obtained. By a curvilinear regression approach, analytical models of competition have been fitted. By statistical and biological criteria of simplicity, reality, generality, and accuracy, the best of these models has been chosen. This model represents an extension of the Lotka-Volterra model of competition; it adds a fourth parameter that controls the degree of nonlinearity in intraspecific growth regulation. It represents a similar extension of the logistic model of population growth.

Animals↗