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Unformatted text preview: state, so the drive system would disappear when the drive allele went to fixation. There will be a window of time where the allele is increasing in frequency, but this could be short-lived. If the drive allele reduced viability in the homozygous state (as the T locus example), then variation can be maintained and the drive system would persist longer, making it more likely to be detected. Another case where genic selection may act: sex ratios. Why should the sex ratio be 1:1 in most diploid species? Assume a sex ratio of 40% males and 60% females. Males in this case are in limited supply. Any gene leading to the production of more males (a allele results in more males the A allele at a sex determination locus) will be favored until the frequency of males is >50%. Sex ratios tend to stabilize at 50:50 (R. A. Fisher, 1930)....
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This note was uploaded on 11/05/2011 for the course BIOLOGY MCB2010 taught by Professor Jessicadigirolamo during the Fall '10 term at Broward College.
- Fall '10