How dendritic ecological networks structure the distribution and movement of stream salamanders

Metapopulation persistence in a complex network results from the interplay between movement pathways and individual-specific movement behavior. In dendritic networks such as streams, some animals are restricted to travel along the network (i.e., within the stream), while others may be able to make out-of-network movements (i.e., over land between streams). The fractal nature of dendritic networks, with many opportunities for movement through the network, may provide substantial benefit to population persistence. However, many real networks (such as urban streams) do not have this regular structure, and should therefore have increased metapopulation extinction rates. Combining theoretical simulations, observational data on population distribution, and empirical data on animal movements, I find that understanding species-specific movement probabilities (and the propensity for out of network movements) are important for assessing metapopulation extinction risk. Realistic networks in nature may fall between the dendritic network topologies considered here, and thus understanding how network complexity interacts with population extinction risk is important for managing these habitats.