Mittler, Sidney||Bennett, Jack (Cecil Jackson)
M.S. (Master of Science)
Department of Biological Sciences
In order to determine the adaptive values of certain combinations of genes of Drosophila melanogaster, flies carrying these genes were placed in Bennett population cages. In one experiment, a population was started with yellow, forked attached-X females in competition with yellow, white, forked and yellow, vermillion, forked, carnation attached-X females. Oregon-R, wild males were put in this population. In a second experiment, the same attached-X stocks were placed in competition with each other, but Canton-S wild males were used. Thus, a genetic system was set up whereby the adaptive values of homozygous recessive mutant genes could be studied without interference of heterozygotes. After each population was well established, wild type females appeared at different periods in each cage. These wild type females may have entered the population through contamination or non-disjunction of the X chromosome in the male. It should be realized that mutations affecting body and eye color and bristle and wing structure also affect other factors such as longevity, hatchabllity, and egg-laying ability. As most mutant homozygotes act to decrease the fitness of an organism and the population as a whole, it would seem that they would be of no value in the process of evolution, However, visible deviations of apparent abnormalities produced in the homozygous condition can be looked upon as an undesirable outcome in nature’s attempt to increase the fitness of an organism. If through heterozygosity a mutant gene is preserved long enough, it Is possible that the homozygotes could be adaptively superior in a different environment or genetic background.
Baran, Marion S., "Competition between various attached-X mutant stocks of Drosophila melanogaster in population cages" (1964). Graduate Research Theses & Dissertations. 1883.
vii, 25 pages
Northern Illinois University
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