Intraspecific variation in sex heterochromatin of species B of the Anopheles dirus complex in Thailand

Abstract

Cytological examination of F1 larval mitotic chromosomes from a total of 126 families of Anopheles dirus species B from southern Thailand populations has revealed a pronounced quantitative variation of constitutive heterochromatin in the two sex chromosomes. Five types of X chromosomes and four types of Y chromosomes have been identified in this study. Such gross variation in sex chromosomes is most likely due to a gradual acquisition of extra heterochromatin. Key words: Anopheles, heterochromatin variation, coevolution, sex chromosomes.