Types of Evolution (intro to evolution pt. 2)

Types of evolution

• Convergent evolution

• Divergent evolution

• Coevolution

• Gradualism

• Punctuated equilibrium

Convergent Evolution

2 species evolve similar characteristics due to common environmental conditions, not common ancestry

- The species have analogous structures

• ex: wings of bat and bird

• ex: fins of shark and dolphin

Divergent Evolution (aka adaptive radiation)

2 or more species arise from a common ancestor

- Can be a result of geographic isolation, driven by particulars of the location

- Homologous structures

• ex: fox and dogs

• ex: Darwin’s finches (13 different species of finches, all differ mainly in beak shape and food source)

Coevolution

The change of two or more species in close association with each other

• ex: predator and prey

• ex: plants and the animals that pollinate them

  • Bats with slender, specialized tongues can feed on nectar of certain flowers, picking up pollen as they do

  • The flowers coevolved with the bats. They are light in color, easily located by bats and smell like fruit, attractive to the bats

  • Bats transfer pollen from one flower to another

Punctuated Equilibrium

• Stephen J Gould hypothesized that evolution is a “standstill” process punctuated by short revolutionary events of rapid evolution

• During these evolution events, species become extinct and are replaced by other wholly new forms

• Supported by the Fossil Record

• ex: a cheetah species has no spots. However, due to a gene mutation, a cheetah cub is born with spots. Because this adaptation helps the cheetah to hide and survive, more cheetahs are born with spots