Processes of SpeciationSections

11.5 and 11.6

Genetic IsolationWhenever genetic information ceases to transfer between two populations, they

are considered isolated

Reproductive IsolationIsolation caused when members of different

populations can no longer produce offspring that can survive and reproduce.

A mule is a combination between a horse and a donkey. While they can produce offspring, the offspring are infertile.

Behavioral Isolation

They have bazaar courtship rituals that are very unique to different species

Isolation caused by the differences in courtship and mating behaviors…remember the birds of paradise.

Geographic Isolation

Isolation due to physical barriers including rivers,

oceans , and mountains…island

s are a great example

Temporal Isolation

These frog species mate at different times and may be the reason for speciation

Isolation due to the timing of

reproductive and courtship

periods…temporal is all about timing!

Patterns in Evolution

Evolution through the process of natural selection is not random. Instead, it has a direction based on environmental factors.

Its important to distinguish that this does not mean that there is intent in the process!

Convergent Evolution

Marine mammal (whales)

Swimming ability

Dorsal fin

Broad flat tail

Sleek body shape

Marine fishes

Swimming ability

Dorsal Fin

Broad flat tail

Sleek body shape

Evolution towards similar characteristics

among unrelated species due to similar

environmental conditions

Convergent evolution

Whales Sharks

Convergent evolution

Bats Birds

Divergent EvolutionWhen closely related species evolve to

become more and more different over time

Ancestral Bat

Fruit Bat

Vampire Bat

Divergent Evolution

Vampire Bat

Click HERE to see video #1

Fruit Bat

Click HERE to See video #2

Coevolution

These fish both benefit from this relationship

The evolution of two species in

response to each other

Can be both beneficial and competitive

Coevolution

Cheetah

Click HERE to watch video #1

Gazelle

Click HERE to watch video #2

Coevolution

In the case of the Gazelle and the Cheetah, both are extremely fast in order to survive.