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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1971 Oct;68(10):2480–2483. doi: 10.1073/pnas.68.10.2480

Polymorphisms in Continental and Island Populations of Drosophila willistoni*

Francisco J Ayala 1, Jeffrey R Powell 1, Theodosius Dobzhansky 1
PMCID: PMC389448  PMID: 5289881

Abstract

A comparative study of genic allozyme and chromosomal polymorphisms in four continental (South American) and six oceanic island (West Indies) populations of Drosophila willistoni has been made. The pattern of genic polymorphism is closely similar in all populations. Although regional and local differences in gene frequencies are found, generally the same alleles occur at high, intermediate, and low frequencies in all populations. An average individual is heterozygous at 18.4 and 16.2% of its loci in the continental and island populations, respectively. By contrast, chromosomal polymorphism is sharply reduced on the islands compared to most continental populations, and some chromosomal inversions are more frequent on some islands than on others. The observations are not compatible with the hypothesis that most of the gene variants are adaptively neutral. Balancing natural selection is responsible for most of the genic polymorphism in natural populations of D. willistoni.

Keywords: Colombia, West Indies, natural selection, chromosome inversions, isozymes, starch-gel electrophoresis

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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