Types of Evolution
Evolution over time can follow several different patterns. Factors such as
environment and predation pressures can have different effects on the ways in
which species exposed to them evolve. shows the three main
types of evolution: divergent, convergent, and parallel evolution.
Figure1.1: Types of evolution; a)divergent, b)convergent, and c)parallel.
Divergent Evolution
When people hear the word "evolution," they most commonly think of divergent
evolution, the evolutionary pattern in which two species gradually become
increasingly different. This type of evolution often occurs when closely
related species diversify to new habitats. On a large scale, divergent
evolution is responsible for the creation of the current diversity of life on
earth from the first living cells. On a smaller scale, it is responsible for
the evolution of humans and apes from a common primate ancestor.
Convergent Evolution
Convergent evolution causes difficulties in fields of study such as
comparative anatomy. Convergent
evolution takes place when species of different ancestry begin to share
analogous traits because of a shared environment
or other selection pressure. For example, whales and fish have some similar
characteristics since both had to evolve methods of moving through the same
medium: water.
Parallel Evolution
Parallel evolution occurs when two species evolve independently of each other,
maintaining the same level of similarity. Parallel evolution usually occurs
between unrelated species that do not occupy the same or similar niches in a
given habitat.
