Adapting to a changing environment using winner and loser effects

Many animals form large aggregations that have no apparent consistent leader, yet are capable of highly coordinated movements. At any given time, it seems like an individual can emerge as a leader only to be replaced by another. Although individuals within a group are largely considered equal, even individuals in a homogeneous group are different. Clearly individuals will differ based on traits like sex, age, and experience. Of particular interest is the idea of individuals differing in their correlated traits, or personality. Different personalities can arise via complex interactions between genes and an environment and are often shaped by individual experience. For example, one would generally predict that individuals characterized as "bold" would more frequently be leaders. However, if the environment changes, how do once successful leaders respond to failure and how do newly successful leaders emerge? Using a biologically-based collective movement model, we demonstrate that a self-assessment mechanism using winner and loser effects is capable of producing transitory leaders who change roles in response to changes in the environment. Furthermore, simulations predict that this self-assessment mechanism allows the group to adapt to drastic changes in the environment and remain successful.