Inoue Yutaka, Watanabe Takao K
Osaka University of Foreign Studies, Minoo, Osaka 562, JAPAN.
National Institute of Genetics, Mishima, Shizuoka 411, JAPAN.
Evolution. 1992 Jun;46(3):797-806. doi: 10.1111/j.1558-5646.1992.tb02085.x.
Drosophila melanogaster populations in nature usually carry inversion polymorphisms. When they were transferred to and maintained in the laboratory as large cage populations, frequencies of polymorphic inversions were drastically decreased and finally eliminated. This "cage effect" was observed irrespective of the geographical origin of the population or the initial frequency of each inversion. The decrease and elimination of inversions in the cage was not overcome by changing conditions such as medium, temperature, or the number of isofemale lines (40-600) introduced. On the other hand, in the sets of isofemale lines derived from the same geographical origins as the cage populations, each of which was maintained as a small vial population, the inversion frequencies, though decreased from the initial frequencies, were kept at significantly high levels. The cage populations initiated with one or two isofemale lines also maintained the inversion polymorphisms that were as high as vial populations.
自然界中的黑腹果蝇种群通常携带倒位多态性。当它们作为大笼种群转移到实验室并在实验室中维持时，多态倒位的频率急剧下降并最终消除。无论种群的地理起源或每个倒位的初始频率如何，都观察到了这种“笼效应”。通过改变条件，如培养基、温度或引入的同雌系数量（40 - 600），无法克服笼中倒位的减少和消除。另一方面，在与笼种群来自相同地理起源的同雌系组中，每个同雌系作为小瓶种群维持，倒位频率虽然从初始频率下降，但仍保持在显著较高水平。由一两个同雌系起始的笼种群也维持了与小瓶种群一样高的倒位多态性。
