An evaluation of behavior’s role in range expansion

Understanding how species ranges evolve is central to a wide range of issues in ecology and evolution. A species’ range can evolve through a variety of factors, one of which is through barriers to dispersal. Physical dispersal barriers are often considered in range dynamics, but the role of behavior in dispersal is less appreciated, though it can have major consequences. For example, the presence of more exploratory individuals at expanding range fronts has been found in some systems yet is still not often acknowledged, motivating us to further investigate the relationship, as it could greatly impact distribution models and ecosystem dynamics. Within our system, we expected that exploratory behaviors associated with higher rates of dispersal would be more prominent among individuals closer to a recently expanded portion of their range. We conducted behavioral tests on Spadefoot toads collected from across their range to examine this relationship in their exploratory behaviors. Higher rates of exploration were found in individuals who were collected closer to the recently expanded range front. This pattern suggests that, as expected, exploratory behaviors are associated with range expansion and would have consequences for predicting future changes to species ranges.  Therefore, behavior may be critical in the development of species ranges, supporting the need to conduct future studies evaluating their mechanisms and role.