Abstract
A study was conducted using small effective population size as an experimental design to test selective neutrality of seven isozyme polymorphisms. Loci varied as to the degree to which the decay of heterozygosity over 21 generations was retarded. Selection for heterozygotes, overdominance, is implicated for at least four of seven loci. Of these ADH gave the largest heterozygote excess in the presence of inbreeding. An interaction between the small population size treatment and excess heterozygosity suggests that (1) the loci studied may be selectively neutral and linked to other loci which are under the influence of selection or (2) the selection coefficients for the loci studied are not independent of the background genotype. In either case four of the seven enzymes studied are signaling the operation of selection. The problem of distinguishing the effect of a single marker from that of a chromosome segment is emphasized. The identification of the genetic unit of selection is crucial to any interpretation of the meaning of enzyme polymorphisms.
Full Text
The Full Text of this article is available as a PDF (1.4 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Clarke B. Darwinian evolution of proteins. Science. 1970 May 22;168(3934):1009–1011. doi: 10.1126/science.168.3934.1009. [DOI] [PubMed] [Google Scholar]
- Hjorth J. P. A phosphoglucomutase locus in Drosophila melanogaster. Hereditas. 1970;64(1):146–148. doi: 10.1111/j.1601-5223.1970.tb02284.x. [DOI] [PubMed] [Google Scholar]
- Johnson F. M. Isozyme Polymorphisms in DROSOPHILA ANANASSAE: Genetic Diversity among Island Populations in the South Pacific. Genetics. 1971 May;68(1):77–95. doi: 10.1093/genetics/68.1.77. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Johnson F. M., Schaffer H. E., Gillaspy J. E., Rockwood E. S. Isozyme genotype-environment relationships in natural populations of the harvester ant, Pogonomyrmex barbatus, from Texas. Biochem Genet. 1969 Oct;3(5):429–450. doi: 10.1007/BF00485604. [DOI] [PubMed] [Google Scholar]
- Mukai T. The Genetic Structure of Natural Populations of DROSOPHILA MELANOGASTER. VII Synergistic Interaction of Spontaneous Mutant Polygenes Controlling Viability. Genetics. 1969 Mar;61(3):749–761. doi: 10.1093/genetics/61.3.749. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Prakash S., Lewontin R. C., Hubby J. L. A molecular approach to the study of genic heterozygosity in natural populations. IV. Patterns of genic variation in central, marginal and isolated populations of Drosophila pseudoobscura. Genetics. 1969 Apr;61(4):841–858. doi: 10.1093/genetics/61.4.841. [DOI] [PMC free article] [PubMed] [Google Scholar]