Speciation: the formation of new and distinct species in the course of evolution.
Speciation and macroevolutionary changes result from an accumulation of microevolutionary changes. Over a long period of time, evolution can result in speciation.
Patterns of diversification
Groups of species undergo various kinds of evolution and, over time, may engage in several different patterns of diversification: convergent evolution, divergent evolution, parallel evolution, and coevolution.
Divergent Evolution
The process whereby groups from the same common ancestor evolve and accumulate differences, resulting in the formation of new species.
Adaptive radiation is a type of divergent evolution where there is rapid diversification of an ancestral population into several ecologically different species.
An example of divergent evolution is the kit fox (Vulpes macrotis) and the Arctic fox (Vulpes lagopus). An example of adaptive radiation would be the Galapagos finches or cichlid fishes.
Evidence of divergent evolution is the pentadactyl limb. This is a homologous feature that is found in chordates. The basic structure is the same in all classes.
This provides an example of divergent evolution where a common ancestral structure has evolved and performs different functions.
Convergent Evolution
The independent evolution of similar features in species of different periods in time. There is a problem when we can assume that certain animals are related, simply because they look similar. For example, bats, birds and insects all have wings, but these organisms don’t have a common ancestor. These structures are analogous. Analogous features arise because organisms live in similar environments and so have become adapted to that environment, not because they have a common ancestor.
Parallel Evolution
The similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure. For example, the evolution of marsupials in Australia paralleled the evolution of placental mammals in other parts of the world.
Coevolution
The influence of closely associated species on each other in their evolution. An example of this are insect-pollinated flowering plants coevolving with their insect pollinators.