Adaptive chromosomal polymorphism in the population of Drosophila immigrans = Drosophila immigrans(초파리)集團에 있어서 適應的 染色體多型現象

국문 초록 (Abstract)

이 硏究는 Drosophila immigrans(초파리)의 染色體 逆位多型現象의 行動을 밝히기 위하여 이루어졌다. 그 特別한 目的은 첫째 人工集團에 있어서 特定한 染色體逆位의 適應的 役割에 關한 증거를 얻는데 있었고, 둘째 어떤 遺傳的 機構가 이들 染色體逆位多型現象의 保存에 關係하고 있는가를 究明하는 데 있었다.
이 硏究를 爲하여 20個의 人工集團을 構成하여 15代間 飼育하면서 各 染色體逆位의 頻度變化를 調査하였다.
自然集團에 있어서 A 逆位의 頻度는 Hawaii 集團에 있어서 有意하게 높았고 Kauai 集團에 있어서는 낮은 頻度를 보였다. 한편 C 逆位는 Kauai 集團에서 가장 높은 頻度를 보였고 Hawaii 集團에서는 낮은 頻度를 나타냈다. 그런데 B 逆位는 兩集團에서 각기 낮은 頻度를 보여 有意한 差는 보이지 않았다.
實驗集團에 있어서는 처음 4世代間에 걸쳐 그 頻度變化가 심하였고 특히 A 逆位의 경우 Hawaii에서 유래한 集團에서는 급격히 빈도가 높은 반면 Kauai에서 由來한 集團에서는 反對로 理論値보다도 낮은 頻度를 보여주었다. 그리고 C 逆位의 경우는 A 逆位의 頻度와 相反된 現象을 나타내었다. 즉 Kauai集團에서는 높았고 Hawaii 集團에서는 낮은 頻度를 나타내었다. B 逆位의 경우는 兩集團에서 그리 顯著한 差異를 나타내지 않았다. 그러나 처음 2世代間은 그 差異를 보였다.
모든 集團은 6,7世代부터 平衡狀態에 들어갔으며 따라서 이들 逆位多型現象은 適應的인 染色體多型現象이라고 보아진다.
이들 集團은 頻度依存淘汰 或은 Relational balance 假說로 說明하는 것이 타당하다고 본다.

다국어 초록 (Multilingual Abstract)

This study tests the behavior of inversion polymorphism in Drosophila immigrans under a laboratory conditions. The specific purposes of the experiment are to a) obtain evidence concerning the adaptive role of specific inversions in genetic adjustment in an artificial environment, b) determine what genetic mechanisms are involved in the maintenance of inversion polymorphisms. For this study, twenty cages containing replicate populations were established in which Drosophila bearing one of three gene arrangements (A, B, or C) were allowed to reproduce.
Frequencies in natural populations indicated that, in a Hawaii natural population, inversion A showed the highest frequency, while inversion C was present in the highest frequency in a Kauai population. In both population, inversion B was the least frequency. In artificial populations of geographically uniform origin, frequency changes of inversion A in the first four generations were quite different from each population group. The observed frequency in Hawaii populations was significantly higher than that expected on the basis of theoretical values, while in the Kauai populations, the observed frequency coincided with expected value. Populations bearing inversion B from either Hawaii or Kauai were similar as regards their mode of frequency change, although differences were observed in the first two generations. The adaptive values which were estimated for inversion C showed differences between the Hawaii and Kauai populations. Their differences were reflected in the equilibria obtained. All of the geographically uniform populations showed that the relative frequencies of gene arrangements reach equilibria at certain levels. This phenomenon suggested that these gene arrangements in artificial populations were not adaptively neutral.
Relational balance and/or frequency dependent selection may be applied to consideration of these populations.