The majority of people agree that evolution is a process that most species go through that constantly impacts them for the ever changing environment. One ongoing debate in evolution is over how evolution happens: does it happen in quick bursts with periods of long delays between the bursts, this idea known as the Punctuated Equilibrium Hypothesis, or is it a gradual change that happens over the span of a long period of time, this idea is known as the Gradual Change Hypothesis. In reality, evolution is a mixture of both of these ideas with certain examples favoring one of the hypotheses over the other. This means that there is no correct answer to how evolution happens, and it happens different for each species each time, and there are several factors that can effect how the evolutionary change happen.
There are several factors that effect the rate at which evolution happens. Factors such as:
Lifespan of Species
Mutation Rate
Physical or Biological Change in Environment
Selective Pressures
Population Size