Sex chromosome variation in natural populations of the Anopheles sundaicus complex from Thailand and Indonesia
Sukowati, S.; Baimai, V.; Andris, H.
Mosquito Borne Diseases Bulletin 13(1-2): 8-13
Analysis of larval mitotic chromosomes of Anopheles sundaicus Theobald has been made from F1 progeny of isofemale lines derived from wild-caught females collected from 9 geographically isolated populations in Thailand and Indonesia. These populations show a similar mitotic karyotype (2n=6) consisting of two pairs of autosomes and one pair of sex chromosomes. Heterochromatin variation has been observed in mitotic sex chromosomes. These types of sex chromosomes have been encountered in three different combinations. In addition, autosome 2 in one population showed different amounts of centromeric heterochromatin. Such quantitative difference of heterochromatin in mitotic karyotypes provided evidence for chromosomal differentiation occurring in natural populations forming recognisable cytological forms of genetic species within the taxon An. sundaicus, viz., form A (2A1, X1, X2, Y1), form B (2A1, X1, X2, Y2) and form C (2B1, X1, X2, Y1). Form A is widely distributed in Thailand and Indonesia, while form B has been found in North Sumatra and Central Java. Form C, however, has been found only in Asahan, North Sumatra, Indonesia.