3 types of evolution

evolution

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

speciation

formation of a new, distinct species due to evolution.

2 organisms are considered distinct species when they produce infertile offspring.

2 organisms of the same species would produce fertile offspring spring

speciation

result of a male lion and female tiger mating in captivity. offspring are infertile.

not a species. hybrid animals

hybrid animals are fertile..?

convergent evolution

2 or more species share similar traits that didn’t come from the same ancestor.

it happens because different species that live in similar environments will develop similar characteristics that allow them to better survive in that environment.

ex. to survive in water, sharks +dolphins developed fins

to survive in air, birds+insects developed wings

these shared structures are called analogous structures (same function, but different origin)

what are the structures in convergent evolution called?

analogous structures

divergent evolution

2 or more species diverge from a common ancestor. the species will look very different from each other, despite sharing the same ancestor.

this happens when part of a population becomes isolated due to migration/geographical barriers.

organisms of the divided population, will become adapted to different environmental conditions.

why do humans, bats, frogs, porpoises, and horses have the same bones in our limbs?

bc we inherited this structure from a common ancestor (same origin)

after being seperated, we lived in different environments and so our limbs evolved to perform different functions

coevolution

evolving together and it is ongoing. this happens when 2 or more species influence each other’s evolution because of their interactions.

example of coevolution: butterflies + birds

1) bird feeds on mimic butterfly (monarch is inedible to birds)

2) mimics evolve to look more like the monarch

3) mimic: increases chance that monarch will be accidentally eaten by birds

4) monarchs evolve to look less like mimics

5) birds evolve to better spot the differences between a mimic and a monarch

example #2 of coevolution

A plant and an insect that is dependent on the plant for food.

the plant population evolved a chemical defense against the insect population.

the insects, in turn, evolved ways to resist the plant’s chemical defense

“arm’s race”, the plant then steps up the race by evolving new defences, the insect escalates its response, and the race goes on