银额果蝇自然群体分化过程中的细胞遗传学

对我国大陆银额果蝇的分布及其细胞遗传学进行了广泛的调查，发现了一种值得注意的新核型。该核型结构兼有早已认可的长、短两大类基本核型的特征，即核型中的两条同源４号染色体为１长１短型。含新核型的群体分布于我国大陆东南沿海一带的上海、福州、厦门和深圳。而且，这些自然群体内还出现“１长１短型”、“长型”和“短型”重叠并存的多态现象。跟踪研究表明，新核型具有不稳定的遗传性，能世代传递，它的频率随世代增长而降低，并不是突然消失。但是，在上海、福州群体内出现的“长型”至第十五代之后却全部消失。这种新核型大概是银额果蝇自然演化过程中的中间过渡核型，是该果蝇种群分化中的细胞遗传学变异的过渡表征

A New Karyotype of Drosophila albomicans

ln the paper, we present a new karyotype of D. albomicans found in the populations from Southeast China. Short chromosome IV of D. albomicans has been reported in Thailand populations while long type was discovered in Taiwan populations. However, we found that long and short chromosome IV coexisting in the same somatic cells. The individuals which contained the "hybrid" cells were collected from Shanghai, Fuzhou, Xiamen and Shenzhen, China. Moreover, the three karyotypes could be detected in each population mentioned above in other words, the populations showed a pattern of karyotype polymorphism. Furthermore, our observation disclosed that the new karyotype was unstable. Its frequency decreased with increasing breeding generation. Since the geographic locations of these populations just lies between the regions of double long and double short type' s populations, this new karyotype seems a intermediate transitional type during the variance process of D. albomicans.