Chapter 17.3 (Pgs. 494-497):The Process of Speciation

Species

- A population or group of populations that can interbreed and produce fertile offspring

- The formation of new species is called speciation

Reproductive Isolation

- Is when some members of a population stop breeding with other members

- Can be caused by physical, behavioral, or temporal barriers

- Can cause speciation

Geographic Isolation- Occurs when a geographic barrier prevents

contact and breeding between members of a population

- Geographic barriers can include:• Bodies of water• Mountain ranges• Glaciers• Forests• Cities and roads

- Can create reproductive isolation- When isolated groups come back into contact,

they do not interbreed

Behavioral Isolation- Occurs when behaviors change

and prevent contact and breeding between members of a population

- Behavioral changes can include:• Food choices• Mating rituals

- Can create reproductive isolation

Temporal Isolation- Occurs when members of a population

mate at different times, which prevents contact

- Can create reproductive isolation

How Darwin’s Finches Evolved- Founders Arrive

- Birds fly or are blown 600 miles to Galapagos

- Geographic Isolation- Birds are now separate from the mainland

populations and other island populations

- Changes in Gene Pools- Birds adapt to local environments, causing

different beak sizes and other adaptations

How Darwin’s Finches Evolved- Behavioral Isolation

- Different mating behaviors prevent breeding with other island populations

- Competition- Competing for food and other resources

causes further adaptations