Here are the three concepts that we are dealing with in our study. In animals, kin selectionfavours altruism towards related individuals more so than towards unrelated individuals. There are many studies in the field on kin selection in insects, chimpanzees, lions and others but no study has looked at fruit flies and we wanted to see if there is altruism in flies. Altruism is an act performed to enhance fitness of another individual at the cost of one’s own. Kin selection is all the evolutionary processes that favour increased fitness of relatives. Indirect fitness is passing on genes through close kin which benefits one’s own fitness. So, all of these combined, we have the evolution of altruism towards kin which has been a topic in studies of social selection, evolutionary psychology and ultimately human nature.
Reason for rearing flies in different vials is to alleviate environmental effects, flies from the same environment have been shown to develop social tolerance for one another.
Reason for pairing same sex flies was to avoid sexual incidences which would have introduced other variables and all sorts of confounding variables because a male might share for reproduction. This is not altruism related to kin selection.Side note: we were not blind to the experiment.
Bio318 Final Presentationn
Does Altruism Differ BetweenIsogenic and Unrelated Fruit Flies? Cigdem Demirez Soham Bhatia Bio318Y http://www.littlebrownbooks.net/sedaris/ March.20.2012
Altruism, Kin Selection and Indirect Fitness• no study on Drosophila•Altruism = sacrificial1•Kin selection: favour relatives2•Indirect fitness: benefits selfthrough relatives3 http://www.shutterstock.com/pic-14703082/stock- photo-male-common-fruit-fly-drosophila- melanogaster1- Kropotkin, Peter. (1902). Mutual Aid: A Factor of Evolution.2- Darwin, Charles. (1859). Origin of Species.3- Hamilton, W.D. (1964). The Genetic Evolution of Social Behaviour. J. of Theo. Bio. 7 (1): 1-16.
Drosophila melanogaster•Wild type -Isogeny: +; BB; +BB•Sexually Dimorphic -easy to differentiate sexes•Short life cycle: -20 to 30 days4 -can study many generations Amsel, Sheri. www.exploringnature.org
Do fruit flies share more with geneticallyidentical versus unrelated flies, if at all? Hypothesis: Fruit flies will show greater altruism in sharing food, if at all, towards genetically identical individuals (isogenic) than towards unrelated individuals. Prediction: If Drosophila are altruistic, a pair of isogenic flies will statistically differ less in time spent at food source in comparison to an unrelated pair.
Experimental Protocol1- Rear Flies2- Experimental trials: 5 groups• pair of: isogenic males isogenic females unrelated males unrelated females•Control: single males & females3- Record Measurements• time spent at food source within 5 minutes
1- Rearing Flies Isogenic M Strain and C Strain 9 families each5 •Sucrose based food •21 ºC •12h light/dark cycle •Relatively humid5-Simon, A.F. et. al. (2012). A simple assay to study social behaviour in Drosophila: measurement ofsocial space within a group. Genes Brain and Behaviour. 11(2): 243-252.
2- Experimental TrialsIsogenic Group: n=30 pairs of - males - females •15 pairs for each strainUnrelated Group: n=30 pairs of - males - femalesControl Group: n=30 single - males - females
3- Measurement•Food deprive for 24 h•Pair similar flies•Measure time spent at food source by each fly•5 minute trials•Time of day: 11 a.m. - 3 p.m.•Assumptions - each fly equally interested to feed
Analyzing Variables•Independent variable: Categorical: -level of relatedness -gender•Response variable: Continuous: time spent at food source•Statistical Test: non-parametric: Mann-Whitney U test
No difference in sharing betweengenetically identical and unrelated flies 200 180 Avg Difference in Time 160 140 120 male 100 female 80 60 40 20 0 control isogenic unrelated
No significance in Values Male Female U = 538 U = 538 Isogenic vs Unrelated P = 0.207 P = 0.193 U = 470 U = 499 Isogenic vs Control P = 0.476 P = 0.312 U = 380 U = 407 Unrelated vs Control P = 0.225 P = 0.312All p-values > α (0.05)All U-values > Ucrit (317)
Conclusion: No difference in sharing between genetically identical and unrelated flies Hypothesis: Fruit flies will show greater altruism in sharing food, if at all, towards genetically identical individuals (isogenic) than towards unrelated individuals. Prediction: If Drosophila are altruistic, a pair of isogenic flies will statistically differ less in time spent at food source in comparison to an unrelated pair.
Why did our predictions fail?1- No knowledge of the degree to how geneticallyunrelated strains are2- Variation in attraction to food3- Spatial factor
Alternative Hypotheses 1- Flies do not have the sharing behaviour because they are genetically adapted to being exposed to ample food resources 2- Drosophila were not eating to conserve food6- Kent, C. et. al. (2009). The Drosophila foraging gene mediates adult plasticity and gene-environment interactions in behaviour, metabolites and gene expression in response to fooddeprivation
ConclusionsDrosophila not shown to share more with genetically identical flies than unrelated flies http://images.ask.com/fr?q=fruit+fly+i n+lab&desturi=httpbwidth