Persistence of chromosomal polymorphism in various strains ofDrosophila ananassae

✍ Scribed by B. N. Singh

• Publisher: Springer Netherlands
• Year: 1982
• Tongue: English
• Weight: 485 KB
• Volume: 59
• Category: Article
• ISSN: 0016-6707
• DOI: 10.1007/bf00133300

✦ Synopsis

Strains of Drosophila ananassae, each descended from a single inseminated female collected in nature, were maintained in laboratory cultures for 10 to nearly 50 generations. The chromosomal analysis of these strains was made immediately after their capture and chromosomal inversions were detected. The same strains were re-examined and it was found that all the strains remained polymorphic during the course of time. Although some of the strains did not show the same chromosomes which were ascertained at the original examination, they failed to become homozygous in all the chromosomes. Some old strains maintained for more than 100 generations but not established by the author were also examined and showed a persistence of inversion polymorphism.

The strains were maintained by transferring between 20 and40 flies to fresh food bottles in each generation and with this breeding system the strains should have become homozygous with respect to most of the unfixed genetic variants which they contained originally. But the strains remained chromosomally polymorphic, which shows that the inversion heterozygotes exhibit heterosis.