Individual Movement of Stream Fishes: Linking Ecological Drivers with Evolutionary Processes

Movement of organisms is an important activity that has ecological and evolutionary implications, including individual reproductive success and survival, population growth and persistence, local adaptation, and gene flow. Expression of movement behavior has traditionally been termed dispersal and measured relative to home ranges. This simplistic approach belies the complexity of the process. Movement of freshwater stream fish has been at times viewed as predominantly restricted in nature, but recent research challenges this paradigm since some distribution of movement exists in every population. A better research approach is to understand the drivers that promote or limit movement. Drivers of movement can be categorized as extrinsic ecological factors (context dependent), e.g., habitat quality, habitat variability, and the presence of predators, and intrinsic traits of the fish (condition dependent), such as body size and condition. One intrinsic trait that has received relatively little attention is the inherent personality to be sedentary or mobile, and how this interacts with the suite of traits and behaviors to drive movement. Future movement behavior research should focus on the interaction of extrinsic and intrinsic drivers to better understand the evolutionary and ecological implications of movement.