Yesterday Sarah Coler, an honors student in the Hoke Lab, defended her honors thesis entitled "Impacts of group composition on the behavioral expression of contributing individuals and on cohesion of group antipredator response." I was Sarah's thesis adviser, and it was great to see this project grow from proposal to finished product. She was supported by an NSF REU during her time on this project.
Sarah approached me with this idea independently. She was interested in asking whether group composition influences individual behaviors, and whether individual behaviors influence group dynamics. She measured multiple female guppies over three days in an open field test to assess consistent differences in exploratory behavior. She then created groups of all exploratory, majority exploratory, majority non-exploratory, and all non-exploratory and let them familiarize for two weeks. She then measured group cohesiveness in an antipredator assay over the course of three days per group. Finally, she re-measured exploratory behavior of each individual following this group experience.
Sarah found that in the all-exploratory and majority non-exploratory groups, individuals became more alike, converging on a less exploratory phenotype. However, individuals in all non-exploratory and majority exploratory groups became more different from one another. Further, all non-exploratory and majority exploratory groups were more cohesive than all exploratory and majority non-exploratory groups. Sarah thinks that a "rare phenotype" effect might be in play, such that individuals will respond more strongly to the "outsider" individual in each group.
After graduation this weekend, Sarah is planning to become a Certified Nursing Assistant to prepare for applying to the Peace Corps. She potentially sees graduate school in her future. Good luck to Sarah!