| Species interactions may frequently evolve across broad geographic scales, with selection coevolutionary within some communities, but commensalistic within others. This variation between coevolutionary selection (hot spots), and commensalism (cold spots), in conjunction with gene flow, selection mosaics, and metapopulation dynamics, comprises the core of the geographic mosaic theory of coevolution. Here I develop a mathematical framework for this theory. I first consider how selection mosaics alter the trajectories of coevolving interactions. I then evaluate the conditions under which coevolutionary hot spots alter the trajectories of evolving interactions. Lastly, I consider how plant polyploidy may reshape the structure of plant-insect interactions, potentially leading to both coevolutionary hot spots, and selection mosaics.; The results from the first two chapters, evaluating the impact of selection mosaics, suggest two primary conclusions. First, selection mosaics frequently lead to hybrid coevolutionary dynamics and cause strong spatial patterns of maladaptation to evolve. Second, matching phenotypes may coevolve in interactions that are mutualistic within only a fraction of their geographic range. The results from the third chapter, investigating the impact of coevolutionary hot spots, suggest that the primary impact of hot spots may be to create novel evolutionary dynamics, and strong spatial patterns of maladaptation. The results from the last chapter, which evaluates how plant polyploidy reshapes natural interactions, suggests that polyploidy has the potential to strongly modify the structure of local interactions, thus providing the raw material for both selection mosaics and coevolutionary hot spots. |
