Population cytogenetics of Drosophila Kikkawai in Thailand

Abstract

Drosophila kikkawai, a member of the montium subgroup belonging to the melanogaster group of the genus Drosophila is quite common and widespread species. Samples from Mae Hong Son population were taken at two month intervals for examined cytologically. D. kikkawai exhibits variation in sizes and shapes of the 4th and Y chromosomes. There were 9 types of 4th chromosome (Lt, Mt, St, Lm, Mm, Sm, Lsm, Msm and Ssm) and 3 types of Y chromosomes, detected in this study. In sprite of six types of 4th chromosome were previously observed and described, it has found more three additional types, St, Sm and Ssm in this study. In addition, it is very interesting that Y1 chromosome has been found, which is the new record in this population. The frequencies of different types of 4th chromosome tended to variation between seasonal changes. The results of the homogeneity test showed the significant differences appeared in a population between seasonal changes. There were eight, from 96 isofemale lines of Mae Hong Son population, showed various conditions of aneuploidy (2n = 8-10). Interestingly enough, five from six collections in this study have been found aneuploidy. And a goodness of fit test showed non significant difference between the season. It was only inversion 3LA has been found in Mae Hong Son population. The frequencies of gene arrangements in the six samples tended to variation between seasonal changes. The result of the goodness of test showed the significant differences exist between the rainy season and the summer. The correlation between mitotic chromosome and inversion polymorphism showed positive correlation. On contrary, the correlation between mitotic chromosome and aneuploid condition showed negative correlation. This result similar to the correlation between inversion polymorphism and aneuploid condition.