Three types of Evolution

Evolution

a process of gradual change that takes place over many generations, during which organisms slowly change some of their physical and behavioural characteristics.

Speciation

formation of a new, distinct species due to evolution

• Two organisms are considered distinct species when they produce infertile offspring

• Two organisms of the same species would produce fertile offspring

Convergent Evolution

• Definition: two or more species share similar traits that did not come from a common ancestor

• Happens because different species that live in similar environments will develop similar characteristics that allow them to better survive in that environment

• Examples:

• To survive in the water, sharks and dolphins developed
  fins

• To survive in the air, birds and insects developed wings

• These shared structures are called analogous structures (same function, but different origin).

Divergent Evolution

• Definition: Two or more species diverge from a common ancestor

• The species will look very different from each other, despite sharing the same ancestor

• Happens when part of a population becomes isolated due to migration or geographic barriers

• Organisms of the divided population, will become adapted to different environmental conditions

• humans, bats, frogs, porpoises, and horses have the same bones in our limbs because we inherited this structure from a common ancestor (same origin)

• After being separated, we lived in different environments and so our limbs evolved to perform different functions

Coevolution

Happens when two or more species influence each other's evolution because of their interactions