Humanity is changing the earth’s ecosystems dramatically: by land use and habitat destruction, hunting/fishing, pollution and climate change. In many parts of the world the composition of the species found in local environments is thus also changing rapidly, with new combinations of species arising never before seen. The future fate of these ’novel‘ assemblages is of great concern: are these new biologic communities stable or will they soon decompose, possibly putting the function of ecosystems, or the survival of the species themselves at risk?