Speciation

How do we get new species on Earth?

What is a species?

• Remember: A species is a group of organisms that can breed and produce viable and fertile offspring.

Two animals are NOT the same species if they

cannot mate and produce a living, fertile baby.

How do new species form?

For a new species to form, members of a current species must be isolated long enough so that they will not interbreed if reunited with their

original population.

How could this happen?

Two Types of Speciation

• Allopatric Speciation – “allo” = different places– Geographic Isolation

• Sympatric Speciation – “sym” = same place– Temporal Isolation– Reproductive Isolation– Behavioral Isolation

Hawaii

Galapagos

Convergent Evolution• Since adaptations are shaped by the environment,

similar environments can lead to similarities in unrelated species.

Fish and dolphins both have fins.

Bats, birds, and insects all have

wings.

Galapagos

Adaptive Radiation

What else can be an “island?” Any isolated area

caves

mountain tops

lakes

Ring Species - Ensatinas

Sexual Selection• Sexual selection is when a selective pressure

affects an organism’s ability to mate and pass on its genes, but not its ability to survive.

• Examples: Bowerbirds, Elk, Beta fish

Check Your Understanding

• 1. What is the difference between allopatric and sympatric speciation?

• 2. Give an example of convergent evolution.

• 3. Explain how Darwin’s finches are an example of adaptive radiation.

• 4. What are some examples of “islands” that geographically separate populations?

• 5. Explain an example of sexual selection.

Test Review

• People– Darwin– Wallace– Lamarck– Lyell– Hutton

• Concepts– Biological Species Concept– Uniformitarianism– Gradualism– Evolution– Evidence for Evolution– Fossils– Phylogenies (trees)– Homologous Structures

– Natural Selection– Extinction– Speciation– Geographic isolation

– Convergent Evolution– Sexual Selection