Article Abstract:
Genetic variation has been measured in surface-dwelling populations of Culex pipiens, mosquitoes, in London and the form called molestus that lives in the London Underground, a subterranean railway system. The molestus strain is commercially significant because it is a biting nuisance. In the southern part of the range it is a disease vector. Genetically, the two strains were different. There was no evidence of gene flow between the two strains, although they are close physically. Different populations of each form differed very little. It appears from substantially reduced hetozygosity in the underground type and from allelic composition that colonization was a one-time event or very close to that. Underground populations have breeding compatibility with each other, but not with those in the open air. In the south of the species range it seems there may be more gene flow and mixing of pipiens and molestus traits. Processes that may allow establishment of reproduction isolation in the north of the species range and not in the south have been considered.
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Article Abstract:
Direct Drosophila melanogaster response to artificial selection on knockdown temperature, the upper temperature at which insects can no longer cling to an inclined surface and a convenient index of high-temperature sensitivity, is discussed. Results suggest one or two loci of large effect and some additive modifiers.
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Article Abstract:
Results show that 80% of genetic diversification in mahogany timber plants is maintained within population and logging decreased population diversity significantly (P=0.034) as revealed by DNA-based RAPD technique.
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