Mosquitofish (Gambusia holbrooki) form shoals in which interactions can be examined as social networks. Social networks form the connection between individual behavior and group dynamics and can influence how information and diseases spread. While the presence of social networks in animal groups is well established, how these relationships form is not well understood. I am examining how individual characteristics influence social status and network structure. To do this, we established sixteen groups composed of five female Gambusia, and observed them twice weekly, for thirty minutes over three weeks. I hypothesize that size differences will determine dominance relationships, which will in turn determine network structure.
Animal interactions with one in social groups are often associated with other aspects of an organism’s biology and ecology. We investigate the role of size in female Eastern mosquito fish, Gambusia holbrooki, in determining how interactions were influenced, and influenced with a male mosquito fish. Males in this species- utilize coercive strategies in order to mate; females typically avoid or attack coercive males, and we predict their size may influence 1) which females are approached by males, and 2) how females respond to a male’s advances. We hypothesized there would be more frequent mating attempts towards, and increased aggression from, larger females. Alternatively, smaller females may be less socially connected and thus face more frequent mating attempts by males.
Predation has critical fitness consequences for organisms, and antipredator behaviors are generally under strong selection. In the Eastern mosquitofish, Gambusia holbrooki, individuals commonly avoid predators, but at times may approach and "inspect" predators. We evaluated how social dynamics in mosquitofish influence their behavioral responses to the presence of a predator - the largemouth bass, Micropterus salmoides. We hypothesized we would observe increased shoaling and predator inspection, typical antipredator responses in mosquitofish. We also predicted that less connected individuals in groups would be more likely to be preyed upon by the bass. To test this, we exposed each group to the bass, first in a confined area of the arena to monitor the social changes in response to the predator’s scent. The bass was then released to swim freely to observe the survival of each fish as they acted as prey.
