Bryant Edwin H, Meffert Lisa M
Department of Biology, University of Houston, Houston, Texas, 77204-5513.
Evolution. 1995 Aug;49(4):626-634. doi: 10.1111/j.1558-5646.1995.tb02299.x.
Selection for increased morphometric shape (ratio of wing length to thorax width) was compared between control (nonbottlenecked) populations and bottlenecked populations founded with two male-female pairs of flies. Contrary to neutral expectation, selectional response was not reduced in bottlenecked populations, and the mean realized heritabilities and additive genetic variances were higher for the bottlenecked lines than for the nonbottlenecked lines. Additive genetic variances based on these realized heritabilities were consistent with independent estimates of genetic variances based on parent-offspring covariances. Joint scaling tests applied to the crosses between selected lines and their controls revealed significant nonadditive components of genetic variance in the ancestor, which were not detected in the crosses involving bottlenecked lines. The nonbottlenecked lines responded principally by changes in one trait or the other (wing length or thorax width) but not in both, and regardless of which trait responded, larger trait size was dominant and epistatic to smaller size. Stabilizing selection for morphometric shape in the ancestor likely molded the genetic architecture to include nonadditive genetic effects.
对对照（非瓶颈）种群与由两对雌雄果蝇建立的瓶颈种群之间增加形态测量形状（翅长与胸宽之比）的选择进行了比较。与中性预期相反，瓶颈种群中的选择反应并未降低，并且瓶颈品系的平均实现遗传力和加性遗传方差高于非瓶颈品系。基于这些实现遗传力的加性遗传方差与基于亲子协方差的遗传方差独立估计值一致。应用于选择品系与其对照之间杂交的联合尺度检验揭示了祖先中遗传方差的显著非加性成分，而在涉及瓶颈品系的杂交中未检测到这些成分。非瓶颈品系主要通过一个性状或另一个性状（翅长或胸宽）的变化做出反应，但不是两个性状都变化，并且无论哪个性状做出反应，较大的性状大小对较小的性状大小具有显性和上位性。祖先中对形态测量形状的稳定选择可能塑造了遗传结构，使其包含非加性遗传效应。
