A spatially explicit model to investigate how dispersal/colonization tradeoffs between short and long distance movement strategies affect species ranges

Many organisms can alternatively expand their range through long- and short-distance movements. Understanding the relative importance of these two strategies in determining species range size is of great interest in ecology and conservation biology. The more distant species move, the lower their probability of finding suitable conditions for survival. Thus, a species has a lower probability to succeed in colonization through long-distance dispersal than through short-distance dispersal, i.e., a tradeoff exists between the two strategies. Here, I investigate this issue by using a spatially explicit model where species move from patch to patch across a fragmented landscape. By analyzing the outcomes of 10,000 simulations run on the model under a wide range of tradeoff scenarios, I identified colonization ability as the strongest predictor of species range, followed by short distance dispersal ability, short distance colonization ability and long distance dispersal ability. Thus, range size of species having two different movement strategies is mainly determined by how far the species can move in the short distance strategy, and by its likelihood to succeed in colonization of distant localities, even if the dispersal/colonization tradeoffs between the two strategies are very small.