Frankham R, Briscoe D A, Nurthen R K
Genetics. 1980 Jul;95(3):727-42. doi: 10.1093/genetics/95.3.727.
Abdominal bristle selection lines (three high and three low) and controls were founded from a marked homozygous line to measure the contribution of sex-linked "mutations" to selection response. Two of the low lines exhibited a period of rapid response to selection in females, but not in males. There were corresponding changes in female variance, in heritabilities in females, in the sex ratio (a deficiency of females) and in fitness, as well as the appearance of a mutant phenotype in females of one line. All of these changes were due to bb alleles (partial deficiencies for the rRNA tandon) in the X chromosomes of these lines, while the Y chromosomes remained wild-type bb+. We argue that the bb alleles arose by unequal crossing over in the rRNA tandon.--A prediction of this hypothesis is that further changes can occur in the rRNA randon as selection is continued. This has now been shown to occur.--Our minimum estimate of the rate of occurrence of changes at the rRNA tandom is 3 X 10(-4). As this is substantially higher than conventional mutation rates, the questions of the mechanisms and rates of origin of new quantitative gaenetic variation require careful re-examination.
从一个有标记的纯合品系建立了腹部刚毛选择品系（三个高选系和三个低选系）及对照品系，以测定性连锁“突变”对选择反应的贡献。其中两个低选系在雌性中表现出一段对选择的快速反应期，但在雄性中没有。在雌性方差、雌性遗传力、性别比例（雌性不足）和适合度方面有相应变化，并且在一个品系的雌性中出现了突变表型。所有这些变化都是由于这些品系X染色体上的bb等位基因（rRNA串联重复序列的部分缺失），而Y染色体仍为野生型bb+。我们认为bb等位基因是由rRNA串联重复序列中的不等交换产生的。——该假说的一个预测是，随着选择的继续，rRNA串联重复序列中会发生进一步变化。现在已经证明确实会发生这种情况。——我们对rRNA串联重复序列处变化发生率的最低估计是3×10^(-4)。由于这大大高于传统的突变率，新的数量遗传变异的起源机制和速率问题需要仔细重新审视。
