Clark A G
Genetics. 1985 Sep;111(1):97-112. doi: 10.1093/genetics/111.1.97.
Observations of intraspecific variation in organelle DNA have prompted a renewed interest in the evolutionary consequences of cytoplasmically transmitted factors. Attempts to quantify the significance of cytoplasmic effects are frequently limited by the difficulty in partitioning the cause of reciprocal cross differences among a series of possibilities. In the experiment reported here the nuclear genomes of a set of six lines of Drosophila melanogaster from diverse geographic locations were replaced in a series of cytoplasms. The segregation of the SM5 balancer chromosome was scored in a factorial design, and the data allowed a partitioning of variance such that cytoplasmic effects were distinguished from maternal effects and meiotic drive. An attempt was made to avoid the confounding problem of hybrid dysgenesis by performing the entire experiment (including chromosomal extractions) in a P cytotype. Results indicated a significant contribution of cytoplasm to the variance in SM5 segregation. Error variance showed an increasing trend as the experiment proceeded, and additional tests indicated that this was due to an accumulation of chromosomal mutations. These findings are interpreted in light of the population genetic theory that addresses the maintenance of cytoplasmic polymorphism.
对细胞器DNA种内变异的观察引发了人们对细胞质传递因子进化后果的新兴趣。量化细胞质效应重要性的尝试常常受到限制，因为难以在一系列可能性中划分正反交差异的原因。在本文报道的实验中，来自不同地理位置的一组六条黑腹果蝇品系的核基因组在一系列细胞质中被替换。在析因设计中对SM5平衡染色体的分离进行评分，这些数据允许进行方差分析，从而将细胞质效应与母体效应和减数分裂驱动区分开来。通过在P细胞型中进行整个实验（包括染色体提取），试图避免杂种不育的混杂问题。结果表明细胞质对SM5分离的方差有显著贡献。随着实验的进行，误差方差呈上升趋势，进一步的测试表明这是由于染色体突变的积累。这些发现根据解决细胞质多态性维持问题的群体遗传理论进行了解释。
