Loners or Lovers: Effects of past social experiences of

Drosophila melanogaster on male mating behavior

Olivia He, Irene Hsu, Dr. Emily McLean
Oxford College of Emory University, GA

Background Methods Results

The effect of social environment on mating success varies by genotype

Proportion of Successful Matings

Environmental and Genetic Factors Work Together to Shape Phenotype:
● Current literature expands beyond the nature-nurture dichotomy of phenotypic Virgin flies
sexed and
determination to the more complex gene by environment interaction model, whereby separated
the genes that influence an individual’s traits are in part influenced by his environment, under CO2
anesthesia
as well as his genetic makeup (Sokolowski and Levine, 2010)

P= Phenotype
a b c E1= Environment 1 Flies were
E2= Environment 2 Male Environment
aspirated into
----------- Genotype 1 mating Figure 4. Proportion of successful matings won by either isolated or socially
___________
Genotype 2 chambers experienced “social” male fruit flies across 12 genotypes. The graph’s crossing
(males first)
and observed lines are resemblant of reference figure 1(c), where the males’ environmental conditions,
for 90 minutes genotype, and the interactions between the two dictated the differences in the observed
phenotype (mating success).
Figure 1. Gene by Environment Interactions. (a) Horizontal slope, differing
phenotypes (P): Significant impact of genotype (G) on P, but neither the environment (E) nor
Conclusion
G × E interaction impact P. (b) Same non-horizontal slope, differing phenotypes: Significant
Results
impact of G and E on P, but no impact of G × E on P. (c) Lines cross; different slopes & Conclusions:
phenotypes: Significant impact of G, E, and G × E on P. ● Of 160 total mating trials, 73 resulted in no mating, 47 resulted in the isolated male
mating, and 40 resulted in the social male mating. With all data combined, we found
Genetic Variance in Drosophila Melanogaster Social Behavior: no significant difference between isolated and social male mating successes.
● However, when broken down by genotype, we see that in some lines the isolated
● In fact, social experience has been shown to impact the sociability (inclination to interact males do well and in others the social males do well, demonstrating that mating
with other flies) and aggressiveness of male fruit flies. behavior is influenced by social environment, genotype and G × E

Genotype
interactions.
Genotype

● However, the degree to which these social experiences impact a fly’s behavior vary
● ANOVA analysis showed that mating latency and mating duration are only
depending on the genotype in question. affected by genotype, not G × E interactions or social environment (p<0.05 for both).
● For the majority of tested genotypes, male fruit flies raised in isolation have been ● For mating duration, there was no significant difference between the average
found to be both less sociable and more aggressive with respect to their mating duration of isolated or social males (p=0.12). On average, social males
counterparts raised in groups of other male flies (Scott et al., 2017) For others, such mated for 1458 seconds and isolated males mated for 1323 seconds.
tendencies are not observed. ● For latency to mate, there was also no significant difference between the average
● As social behaviors like these are thought to evolve through natural selection, they must mating latency of isolated or social males (p=0.42). On average, social males took
have a genetic basis and ultimately impact an individual’s fitness. 1427 to mate and isolated males took 1690 seconds to mate.
Future Research Directions:
Broad Hypothesis ● This study is part of an ongoing research initiative of the McLean Lab; our findings will
● Our study examines the effects of social environment, genotype and gene by Average Latency to Mate (Seconds) Average Mating Duration (Seconds) guide the experimental design of future experiments.
environment interactions on male mating success. To determine this, we ● The overarching impact of genotype on all of the phenotypes we recorded leaves us with
the question of: what specific genes might account for the observed differences
measured the proportion of mating trials won, latency to mate, and mating Figure 2. Average latency to mate Figure 3. Average Mating duration
across genotypes? Further experiments could incorporate genome sequencing to isolate
duration of social and isolated male flies across 12 genotypes. of isolated and social male flies of both isolated and social male genes responsible for influencing mating behavior.
● We hypothesize that overall isolated male fruit flies would be more successful at mating across 12 genotypes. The distance flies across 12 genotypes. The ● Using larger sample sizes to re-evaluate the proportion of successful matings between
given their increased aggression compared to their socialized counterparts. between medians in each box plot distance between medians in each box isolated and social flies would better reflect the G × E interactions.
● Given our hypothesis, we predict that higher proportions of isolated males will indicates a significant difference in plot indicates a significant difference in
successfully mate with females, with shorter latency to mate and longer mating duration. average latency to mate between each average mating duration between each
genotype, suggesting that genotype was genotype, suggesting that genotype was Acknowledgements
an important factor in determining how an important factor in determining how
We want to thank the Oxford College of Emory University’s SORS program, specifically Dr.
long it took a male fruit fly to mate. long a male fruit fly would mate for.
Jill Petersen Adams and Ms. Regina McGuire Barrett, for supporting student research.

References
Scott, A., Dworkin, I., Dukas R. “Sociability in Fruit Flies: Genetic Variation, Heritability and Plasticity.” Behavioral Genetics, 2018, vol. 48(3), pp. 247-258
Sokolowski, M., Levine, J. “Nature-nurture interactions.” Social Behaviour : Genes, Ecology and Evolution, 2010, Cambridge University Press, pp. 11-28