Flexi Says: Darwin thought that evolution occurs gradually. This model of evolution is called gradualism. The relationship between flowers and their pollinators is obviously important. What happens if a flower is able to attract more pollinators? A species of flowers adapt over time to attract more bees, a change encoded in the flower's DNA that allows the flowers to spread their pollen further and increase the size of the population. The adaptation is advantageous to the flowers and, after a long period passes, the flowers all gradually adopt the adaptation. The fossil record better supports the model of punctuated equilibrium. In this model, long periods of little change are interrupted by bursts of rapid change. Lake Victoria in East Africa, for example, is just a million years old, and yet it is home to more than 300 species of cichlid fish found nowhere else. Cichlid evolution is an example of adaptive radiation similar to that of Darwin’s finches and Hawaiian honeycreepers, discussed in the Evolution concepts. The fossil record shows similar opportunities for accelerated evolution after mass extinctions.
