A laboratory study of crosses of captive fruit flies (Drosophila melanogaster)
There are ca.1,500 species of Drosophila sp. which are found in multiple habitats. The fly originated in tropical West Africa and breeds in a variety of rotting fruits. They are saprophytic, feeding and ovipositing in rotting plant, and, sometimes, animal matter. They are holometabolous, undergo metamorphosis and are ideally housed in a laboratory at 18-25°C. Stocks of infrequently used strains are often kept at lower temperatures in order to slow down development. Under normal circumstances, at 18°C, complete development takes ca.3 weeks. In the current investigation, two captive sub-types were chosen: Wild (long winged, pale striped abdomen, WWSS) and Vestigial (short winged, ebony striped abdomen, wwss) Type. Flies were stilled in ice and sexed on a cold tray. Three Wild Type of each sex were chosen and mated with the opposite sex of three Vestigial Type. Three of the subsequent F1 generation (WwSs, 1:0) were collected and mated and the ratio of the F2 phenotype noted. Each glass vial contained pre-prepared nutrient agar. Commonly used in college and university laboratories, these flies form an important molecular model in Biological research, are cheap to rear, can be studied based on inherited alleles, and used to predict the likelihood of genetic diseases and their progression in humans.
Wild flies were captured and separated into the following types: captive breeding of Wild type and Vestigial type were reproduced (embryonic stage, three instars and pupae) to produce the F1 generation, followed by a subsequent cross (F2). A Chi-Squared statistical test was used to predict the proportion of phenotypic characteristics in the progeny (p<0.05). Consideration of the use of fruit flies as a molecular tool was discussed.
The tubes in sequence include the Fo, F1 and F2 crosses. The lifecycle and methodology for F2 crosses are presented on whiteboards.
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