THE ORIGINS OF THE JAPANESE MAINLAND POPULATION OF DROSOPHILA-ALBOMICANS

Drosophila albomicans is a species widely distributed but mainly in So utheast Asia. In its traditional distribution, there are substantial g enetic differentiations among three geographic areas, Southeast Asian continent, Taiwan and Nansei islands. In the last decade, however, thi s species has invaded the Japanese mainland and is now spreading its d istribution area to western Japan. In this study, variations of chromo somal arrangements, allozymes and sex ratio in F2 hybrids with D. nasu ta were examined to identify the origins of the newly colonizing popul ation. The results strongly suggest that the origins of Japanese mainl and population can be found in Taiwan.