A Molecular Quantitative Genetic Study of Epistasis and Its Evolutionary Role

9419992许多性状受多个基因的影响。研究这些基因之间的相互作用，上位性，对于理解这些复杂性状的遗传基础是必不可少的。例如，基因相互作用可能会导致一些家庭发生疾病，但不会导致其他家庭发生疾病，这取决于这些家庭中的哪组基因。上位性的程度对于小种群应对选择压力、避免灭绝或作为物种形成的一部分的灵活性也很重要。我们将测量基因交互作用对小鼠成年体重的影响，然后跟踪这种交互作用对小种群动物之间遗传差异的影响。标准的种群遗传理论预测，随着近亲交配发生在较小的种群中，遗传差异将急剧下降，从而限制了它们的进化潜力。然而，结合上位性效应的新模型预测，近亲交配的遗传差异水平只会略有下降，甚至会增加。两个近亲交配品系的小鼠将被杂交。这个杂交将衍生出50个小种群(4只动物)和2个大种群(100只动物)。小鼠之间遗传差异的总体平均水平以及先前发现的每个基因的差异将在大种群规模处理和小种群规模处理之间进行比较，并根据包含上位性的进化模型解释结果。

9419992 CHEVERUD Many traits are affected by multiple genes. Studying the interactions among these genes, epistasis, is essential for understanding the genetic basis for these complex traits. Gene interaction, for example, may cause a disease to occur in some families but not others depending on what sets of genes are in those families. The extent of epistasis is also important for the amount of flexibility available in small populations to respond to selective pressures, to avoid extinction or as part of speciation. The amount of gene interaction on adult body weight in mice will be measured and then the effects of that interaction on inherited differences between animals in small populations will be followed. Standard population genetic theory predicts a sharp decline in inherited differences as inbreeding occurs in small populations, thus limiting their evolutionary potential. However, new models incorporating the effects of epistasis predict only a slight decline, or even an increase in the level of inherited differences, with inbreeding. Two inbred strains of mice will be crossed. Fifty small populations (4 animals) and two large populations (100 animals) will be derived from this cross. The overall average level of inherited differences between mice and the differences due to each previously identified gene will be compared between the large and small population size treatments and the results interpreted in the light of evolutionary models incorporating epistasis.