Diagram indicating the four experimental metapopulation treatments. Diagram indicating the four experimental metapopulation treatments. I, isolated treatment (four local populations separated by Plexiglas barriers to prevent seed migration); L, long treatment (four local populations separated by 49.5 cm); M, medium treatment (four local populations separated by 23.2 cm); and C, continuous treatment (four local populations that are adjacent to each other). Each of the four local populations that make up the metapopulation consisted of a pair of pots, one of which contained plants (hatched circle) and one of which contained bare soil (open circle). At each generation, the bare soil pot received seeds dispersed from the other pots and therefore constituted the next generation. To initiate the experiment (generation 0), one plant was placed into each of the four hatched pots. Once 80% of the plants dehisced their seeds, all pots containing plants were removed for harvesting (simultaneously to simulate discrete generations) and were subsequently replaced with fresh pots of bare soil. By repeating this procedure (growth, dispersal, and harvest of original plants, followed by replacement with bare soil pots), we were able to maintain metapopulations for 15 generations or until all local populations within a metapopulation went extinct. Jane Molofsky, and Jean-Baptiste Ferdy PNAS 2005;102:10:3726-3731 ©2005 by National Academy of Sciences