David J R, Gibert P, Legout H, Pétavy G, Capy P, Moreteau B
CNRS, UPR 9034, Laboratoire Populations, Génétique et Evolution, Bât. 13, 91198 Gif sur Yvette, France.
Heredity (Edinb). 2005 Jan;94(1):3-12. doi: 10.1038/sj.hdy.6800562.
Founding isofemale lines from wild collected females is a basic tool for investigating the genetic architecture of Drosophila natural populations. The method permits the analysis of quantitative traits under laboratory conditions, with a much broader scope than the mere evidence of a significant genetic heterogeneity among lines. Genetic variability is generally demonstrated by a significant coefficient of intraclass correlation, but several experimental precautions are needed and explained here. The relationship between classical (additive) heritability and intraclass correlation is not straightforward, presumably because the genetic bottlenecks due to the initiation of the lines unravel a significant, nonadditive genetic variance due to dominance and epistatic effects. It is thus suggested to consider intraclass correlation as a specific genetic parameter that enables comparisons between different traits, different populations or different environments. The use of isofemale lines is, however, not restricted to the calculation of an intraclass correlation. It can be used to estimate genetic correlations among traits or environments. The method is also convenient for the analysis of phenotypic plasticity in relation to an environmental gradient. A precise description of the response curves (the reaction norms) is possible, distinguishing trait parameters and plasticity parameters. A fairly general conclusion is that, for a given trait, mean value and plasticity are genetically independent. It is also possible to analyze traits, which, like sexual dimorphism, must be measured on different individuals, and even to demonstrate their genetic variability. In many cases, further empirical and theoretical analyses are possible and needed. It is argued that, in the future, isofemale lines will have an increasing significance among the various techniques appropriate to the analysis of quantitative evolutionary genetics in a diversity of species.
从野外采集的雌性果蝇建立同雌系是研究果蝇自然种群遗传结构的基本方法。该方法能够在实验室条件下分析数量性状，其范围比仅仅证明品系间存在显著遗传异质性要广泛得多。遗传变异性通常通过显著的组内相关系数来证明，但这里需要并解释一些实验注意事项。经典（加性）遗传力与组内相关之间的关系并不直接，可能是因为品系起始时的遗传瓶颈揭示了由于显性和上位性效应导致的显著非加性遗传方差。因此，建议将组内相关视为一个特定的遗传参数，它能够用于比较不同性状、不同种群或不同环境。然而，同雌系的用途并不局限于计算组内相关。它可用于估计性状或环境之间的遗传相关性。该方法也便于分析与环境梯度相关的表型可塑性。可以精确描述响应曲线（反应规范），区分性状参数和可塑性参数。一个相当普遍的结论是，对于给定的性状，平均值和可塑性在遗传上是独立的。还可以分析像两性异形这类必须在不同个体上测量的性状，甚至可以证明它们的遗传变异性。在许多情况下，进一步的实证和理论分析都是可行且必要的。有人认为，未来同雌系在适用于分析多种物种数量进化遗传学的各种技术中将具有越来越重要的意义。
