Processes of Macroevolution

divergent, convergent, coevolution and parallel

the differentiation of distinctly different species (or populations) from a common ancestral species (or population) refer to book for diagram

rapid divergent evolution of a large number of related species from a common ancestor

evolution through natural selection of similar features in unrelated groups of organisms due to similar environmental pressures refer to book for diagram

Occurs when related species evolve similar features independently refer to book for diagram

Species that interact closely exert selection pressures on each other. Both species therefore also experience the same environmental pressures. This results in two species evolving together in a reciprocal response to the various pressures

Evident in predator-prey relationships. Once the weaker prey have been eliminated from the population, the predators need to evolve to be stronger and faster to keep up with the strengthening features of the prey.

A high level of genetic diversity allows populations to survive new or changing environments, which may lead to adaptation. Conversely, low genetic diversity increases the risk of extinction, as seen when species or populations go through a genetic bottleneck.

Random events such as natural disasters, the allele frequencies are unlikely to represent the original population and genetic drift may occur. Reduced population sizes results in fewer reproductive pairings - leading to increased inbreeding (results in high numbers of homozygous individuals)

Smaller populations