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Vol. 37 No. 4, 1998
Chromosomal Inversion Polymorphism in Natural Populations of Drosophila ruberrima
Shu
Fang1,2, Fei-Jann Lin2 and Hwei-yu Chang1,2,*
1Department
of Entomology, National Taiwan University, Taipei, Taiwan 106
2Institute of Zoology, Academia Sinica, Taipei, Taiwan
115
Shu
Fang, Fei-Jann Lin and Hwei-yu Chang (1998) The standard map of
the giant polytene chromosome of Drosophila
ruberrima, one of the members of the immigrans species subgroup
of the immigrans species group, is constructed according to the
primitive gene arrangement or standard sequence (8T) for each
chromosome. A pure line with homozygous chromosomes was established.
Chromosomal inversions can be identified easily by crossing a male fly
with the pure line and checking the F1 with the aid of this
standard map. Inversion polymorphism, both kinds and frequencies, of
this species is high. The Taiwan population is at Hardy-Weinberg
equilibrium, but the Yunnan population shows an excess of homozygotes
which is probably affected by natural selection. The geographic pattern
of chromosomal inversion polymorphism in natural populations reveals
that the marginal island population, Taiwan, is less variable than the
central mainland population, Yunnan, mainland China. Little genetic
differentiation among subpopulations within Taiwan indicates that
extensive gene flow exists. In contrast, moderate genetic
differentiation was observed between the Taiwan and Yunnan populations.
Key words: Drosophila
ruberrima, Genetic differentiation, Genetic variation, Inversion
polymorphism.
*Correspondence: Corresponding address: Department of
Entomology, National Taiwan University, Taipei, Taiwan 106, R.O.C. Tel:
886-2-23630231 ext. 3077. Fax: 886-2-27325017. E-mail:
hwei@ccms.ntu.edu.tw
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