The collective behavior of societies emerges from self-organized interactions among group members. Traditionally, group members have been thought of as identical individuals, but behavioral variation is prevalent in nature. This variation can be extreme and one group member, referred to here as the keystone individual, may have a greater impact on the collective behavior of a group than all other individuals. For example, some individuals may lead a group, tutor others or function as super-spreaders of information or disease. Despite the potential impact of keystone individuals on the success of a group, little is known about how and why this influence emerges. The investigators will use social spiders that can be easily manipulated and observed at the individual and group levels to test hypotheses about the emergence of collective behavior, hypotheses that cannot be easily evaluated in more complex systems. In addition to the numerous undergraduate and graduate research projects this project will generate, the proposed work will also be translated into hands-on activities about collective behavior geared towards the education of K-12 students though established and successful outreach programs. Adult science education activities to enhance public knowledge of invertebrate biology will include public lectures, media coverage, and conversations at local communities where the field work occurs.
This research aims to examine the mechanisms by which keystone individuals affect collective behavior, the effects of keystones on the development of collective behaviors and the ecological and evolutionary consequences of the presence of keystone individuals in groups. Using a model system that allows for detailed experimental manipulations, the social spider (Stegodyphus dumicola), will allow the investigators to develop a broad theory to enhance the progress of science on keystone individuals. Specifically, this work will (1) test whether keystone individuals produce tradeoffs among colony-level processes such as prey capture and disease spread, and how these tradeoffs change colony performance in different environments; (2) uncover the temporal dynamics of the effects of keystone individuals on the development of collective behaviors in the field; (3) elucidate the behavioral mechanisms that underlie the catalytic effects of keystone individuals on the behavior of other group members and collective outcomes; and (4) design versatile agent-based models that will uncover the general mechanisms by which keystone individuals influence collective behaviors. The investigators will address these questions by combining lab and field experiments, analyzed with sophisticated image analysis technology and social network theory, with computational modeling. Published data sets will be uploaded for use by others to Dryad.