A Study of Molecular Population Genetics on the Aspect of Edaptive evolution in Drosphila

在基因分子数据积累的过程中，中性分子进化理论(Kimura，1968)的普遍性已被人们所接受。Mukai和他的同事们已经证明，大多数蛋白质的多态是选择性中性的。本研究的目的是在分子水平上考察适应性进化的来源--遗传变异，并验证中性理论对这些实验数据是否具有可操作性。1.生活力的加性遗传方差存在由北向南的变异。这表明，一些平衡选择正在对这些变异群体进行。我们研究了北方(阿森里)和南方(小川原)群体中4个基因区域(adh、Amy、Gpdh、Punch)的Southern限制性内切酶多态性。限制酶切位点的多态性没有显著差异，但插入a…的多态性有显著差异更多的删除。在南方种群中观察到较大的差异。这一事实可能表明，北方种群的超额加性遗传变异反映了这些变异的累积效应。2.Gpdh基因的重复或三倍体存在多态现象。指出基因复制是基因进化的重要机制。这些变异似乎维持在突变发生和净化选择之间的平衡，或通过随机遗传漂移。此外，我们还获得了一个证据，证明这些基因是通过不平等交换而以一致的方式进化的。3.转座子约占果蝇基因组的10%，经常造成复杂的突变。转座率是评价这些突变对适应性进化贡献的重要参数之一。利用突变累积线，我们估计了几个转座元件的转座率。这是此类估计的第一个可靠结果。4.比较了几种转座子在南方和北方群体中的分布。一些类似拷贝的元素在两个种群之间表现出数量上的差异。5.研究了P元素活性和分子结构对群体结构的影响。我们得到的证据表明，在P元素的入侵过程中，它会造成大量的遗传负荷。P元素的长度也有变化。全尺寸元素的分布在种群间存在差异，但在所调查的所有种群中，Kp类元素的出现频率都在增加。较少

The generality of the neutral theory of molecular evolution (Kimura, 1968) has been accepted in the course of accumulation of molecular date of genes. Mukai and his colleagues have shown that most of the protein polymorphisms are selectively neutral. The purpose of this study is to investigate the genetic variation, that is the source of adaptive evolution, in molecular level and testify whether the neutral theory is operational for these experimental data.Following things have become clear in this study. 1. We have shown that there is north to south cline in the additive genetic variance in viability. This is suggesting some of balancing selection is operating on these variations population. We studied restriction enzyme in southern polymorphism in four gene regions (Adh, Amy, Gpdh, Punch) in north (Amori) and south (Ogasawara) populations. There is no significant difference in restriction site polymorphisms, but significant difference was detected in the polymorphisms in insertions a … More nd deletions. Large amount of difference was observed in the southern population. This fact may suggest that excess additive genetic variance in the northern population is reflecting the cumulative effect of these variations. 2. The duplication or triplication of Gpdh gene is found to be polymorphic. It is pointed that gene duplication is important mechanism of gene evolution. These variation appeared to be maintained in the balance between mutational occurrence and purifying selection or by random genetic drift. Furthermore, we obtained an evidence that these genes evolved in concerted fashion by unequal crossing-over. 3. Transposable elements occupy about 10% of Drosophila genome and they often create complicated mutations. Transposition rate is one of the important parameter in evaluating the contribution of these mutations to adaptive evolution. Using mutation accumulation lines, we estimated transposition rates of several transposable elements. This the first reliable of such estimations. 4. We compared the distribution of several transposable elements in southern and northern populations. Some copia like elements shows difference in number between two populations. 5. We investigated the population structure concerning to P element activity and molecular structure. We obtained an evidence that in the course of invasion of P element, it causes large amount of genetic loads. There is variation in the length of P element. There is interpopulational difference in the distribution of complete size elements, but the frequency of KP like elements is increasing in all the populations investigated. Less