I'm not asking about an exotic species in the modern world we know all too well the havoc that can be caused by the introduction of an alien species into an existing ecosystem. I want to know if a novel evolutionary adaptation could create a species which wipes out the rest of the ecosystem it evolved in.
In particular I'm wondering if something similar to the Manchineel could evolve and through a relatively minor mutation and change in it's biochemistry kill off the rest of the ecosystem around it and then take over the newly vacant floral niches?
For the purposes of this question assume a bare-bones ecosystem without land-dwelling vertebrates or grasses but with trees flowers and insect life. Furthermore assume the plant taking over is in fact wind pollinated and thus independent of other organisms for it's propagation. I'm wondering about how realistic causing the total extinction of other multi-cellular life on land is rather than simply forcing other lifeforms into niche environments.
This is an extension of some ideas spurred by Why wouldn't my colonists go to see what's going on down there? and Planet with no rain, only fog, like Chile's Atacama Desert, reference to which may or may not be helpful.