Evolution in heterogeneous environments: speciation

Up to now we have been looking at what might be called metabolic adaptation.

Any 'real' environment, however, is structured. It is not uniform, like our constantly rotating cultures. The very process of life produces a structured environment.

In fact, most microbial organisms live in what are knows as biofilms – structured communities that often contain many different types of organisms.

In the unstirred culture gradients of oxygen and nutrients are established at the air/liquid interface.

Each culture is a microcosm: these small (6ml) cultures will be either stirred (homogenous) or unstirred (heterogeneous). We will incubated the cultures for seven days at 28°C.