If nature is a kaleidoscope of species

If nature is a kaleidoscope of species, constantly reorganizing and adapting, then newcomers will come and go, often in largely random ways. They will fit in as they can, with no more likelihood of doing harm or good than natives. They are not good or bad, not at a special advantage or disadvantage. They just are. This doesn't mean there isn't any evolution going on. Far from it. There is growing evidence, as we shall see later, that the arrival of new species often creates a burst of evolution and hybridization among both hosts and newcomers as they learn to rub along. But the context is a dynamic, open and unpredictable environment, rather than one in which a fixed group of natives is working to some idealized perfect state.

Fred Pearce, The New Wild (Icon Books Ltd, 2016) pp. 189-190