Welcome back to science! Today, you will publish the final draft of your fruit fly DYO on your blog.
Title your post: DYO #2: Fruit Fly Population Investigation
Use the
DYO Worksheet and
Analysis and Conclusion Worksheet to help you.
Your DYO should include the following parts:
- Problem (Question):
- Hypothesis:
- Background Research:
- Procedure:
- Data Table and Graph (click here for photos of your graphs - C2, C3, C4, C5):
- Analysis:
- Conclusion:
David, Alyssa and Melissa's DYO #2: Fruit Fly Population Investigation
Problem (Question): How does the ratio of males to females affect the fruit fly population in a controlled environment?
Hypothesis:
If (IV) I put 1 male and 2 females in a vial with a food source for 3 weeks,
then (DV) I expect to see 326 adults at the end of three weeks. I think this
because every day the female lays 20 eggs. After 14 days, the first 20 eggs that were laid become adults until day 21, when 8 sets of 40 eggs have become adults. This makes 320 adults plus the original 6 fruit flies (2 males and 4 females).
Background Research: The fruit fly is an insect that has four different stages of life; egg, larva, pupa, adult . The egg looks like a tiny grain of rice. The larva looks like a little white worm. The pupa looks like a cocoon. The adult looks like a miniature fly. The egg and larva stage is 8 days long. The pupa stage is 6 days long. Adult fruit flies come out of the pupa after a total of 14 days. 2 days after hatching, an adult fruit fly is able to lay her own eggs (handout from teacher). Adult female fruit flies can lay about 20 eggs per day (
Wikipedia). You can tell the difference between a male and female fruit fly by looking at their abdomen. Male fruit flies have a dark tip. Females have a lighter colored tip (handout from teacher).
Procedure:
- Step 1: I set up three different vials with a food source and 2 males and 4 females in each one. This made a ratio of 2 to 1 (2F:1M).
- Step 2: Place vials together in bin at room temperature.
- Step 3: Check vials each week and record observations (i.e., number of adults, number of pupae, existence of eggs and larva, any strange or unusual activity)
- Step 4: At the end of 3 weeks (on day 21), use FlyNap to put flies to sleep. Empty out sleeping flies on an index card, record the number of adults on your data table and put the flies back in the vials.
Data Table and Graph: The effect of (IV) the ratio of males to females on (DV) the number of adults after 3 weeks.
Analysis: I looked at 3 vials that each had 1 male and 2 females. Each vial had a different number adults at the end of 3 weeks. Vial 1 had 52 adults. Vial 2 had 127 adults. Vial 3 had 12 adults.
In the beginning of my experiment, I hypothesized that
if I put 1 male and 2 females in a vial with a food source for 3 weeks,
then I expect to see 326 adults at the end of three weeks. I thought this
because every day the females lay 20 eggs each. After 14 days, a batch of 20 eggs becomes adults. Therefore, starting at day 14, the first set of eggs (40) will become adults. Each day after that, another set of 40 eggs becomes adults. This continues up until day 21, when there should be 320 new adults plus the original 6 for a total of 326 adults.
My data
does not support my hypothesis because the average number of adults in my three vials was 63.6. This is nowhere near what I predicted. It is way lower.
Two possible reasons for the difference between my results and my hypothesis are carrying capacity and human error. Carrying capacity is the amount of organisms that can be supported by an ecosystem. The vials I used might have been too small to allow fruit flies to breed up to their potential like out in nature. The amount of food I used might have not been enough. Further, the temperature might not have been ideal. Secondly, I noticed a bunch of dead adult fruit flies that had drowned or got caught in the foam top when I went to count my fruit flies. These dead fruit flies were difficult to count and could have changed my results.
Conclusion: In my experiment, I tried to find out if the number of fruit flies I predicted there to be after three weeks could be replicated in a real-world situation. After figuring out the number that I thought there would be, I set up my experiment and monitored it for results. During my experiment the fruit flies reproduced, but not quite as much as I thought they would. At the end of the experiment, my data did not match my hypothesis. This could be because the carrying capacity of the vial was lower than the carrying capacity of an ecosystem where the flies could reproduce naturally. The data could have been lower because of human error as well. There were flies that got caught in the food at the bottom of the vial. If I repeated this experiment I would want to give the flies more space and food to live. I would also make sure that the vials were stored correctly (ex: the right temperature, standing up). Something I'd like to investigate further is whether or not the temperature of the room they are stored in affects how much they reproduce.
