Fruit-fly protocol
Experimental testing of Asymmetrical Sex Evolution using fruit Fly.
Materials:
- Drosophila melanogaster (13 days to go from egg to sexually mature)
- Starter Kit with most materials
- Drosophila vials: 25-30mm diameter narrow tubes with cotton or foam added to the top to prevent flies from flying out. Food is added to each tube much like how agar is coated on plates for bacterial growth.
- Food: Mixture of carbohydrates, Fruit, yeast and water. (kit provided)
- Environment: 25C at 60% humidity. This allows for a generation time of only 9-10 days. Keep out of direct sunlight or heat sources as this spoils media and leads to male sterility.
- http://www.keepinginsects.com/general-care/breeding-fruit-flies/
- Common foods include honey, pieces of fruit as well as water that is UV treated with a chloride at a minimum of 2ppm.
Methods:
- 4 cages will house roughly 100 flies of equal genders. There will be differences in genotype however our focus is on Skin color of the population. The colors needs to be ones that exhibit codominance (a model where there is a spectrum of color. Such that the two homozygous are on the extreme end of the spectrum (White/Black) and all heterozygotes lie in the gray spectrum.)
- Alternative
using Eye size and Light. [Lighting systems. Equipped with a dimmer
to reduce brightness of the bulb and another at full 100W. The lighting
should not be too close to the cage to affect temperature.]Two cage
will contain a dim lighting system, which would be advantageous to flies
with larger eyes, and the other two would contain a bright lighting
system, which would be advantageous to flies with small eyes to filter
out light. The food sources (Fruit) will be moved into random spots
within the cage to prevent any learning associated with food location.
This relies on the fruit flies sight to locate food and not any sort of
memory acquired. All eggs and larvae will not be allowed to grow until
forced selection occurs.
- Forced selection is the following. Fruit flies mature after 1-2 weeks. Egg and larval stage is 8 days. 24 hours after female lays eggs they become larvae. At a certain time point (5-6 days) the gender one cage containing the advantageous trait (i.e. males with large eyes in dim lighting) would all be removed. This would be repeated in the other cages and with the opposite sex. Once forced selection occurs the eggs and larvae formed 2 days afterwards will be permitted to grow.
- The population size will be recorded before and after forced selection in addition to daily.
- Every generation will be performed the same way (gender removal, recording of flies that were removed vs. remaining, recording of eye size within group remaining for both sexes. ( Running these in parallel is best. Possibly doing 10 vials of around 100 flies. This way you can achieve a large population size whilst keeping costs down)