11.5 Speciation Through IsolationSet up Cornell Notes on pg. 29•Topic: 11.5 Speciation Through Isolation

•Essential Question:1.How did geographic isolation affect the diversity Darwin observed in the Galapagos finches?

2.Why are the flash patterns of fireflies considered to be behavioral isolation?

2.1 Atoms, Ions, and Molecules

11.5 Speciation Through Isolation

1. How did geographic isolation affect the diversity Darwin observed in the Galapagos finches?

2. Why are the flash patterns of fireflies considered to be behavioral isolation?

11.5 Speciation Through Isolation

KEY CONCEPT New species can arise when populations are isolated.

Isolated

11.5 Speciation Through Isolation

• If gene flow between two populations stops for any reason, the populations are said to be isolated

– As populations adapt to their environment, their gene pools change

– Changes add up over many generations

– Populations become more and more different

– Start to look and behave differently from one another

11.5 Speciation Through Isolation

• Reproductive isolation occurs when members of different populations can no longer mate successfully with one another– It is the final step of becoming separate species

11.5 Speciation Through Isolation

• Speciation is the rise of two or more species from one existing species due to reproductive isolation.

11.5 Speciation Through Isolation

Populations can become isolated in several ways.

1. Behavioral isolation- is caused by differences in courtship or mating behaviors

– Changes in chemical scents, mating dances, songs or signals can prevent mating

Ex: Fireflies produce patterns of flashes that attract their mates. Over 2000 species of FF are isolated based on the patterns of flashes

11.5 Speciation Through Isolation

2. Geographic isolation- involves physical barriers that divide a population into two or more groups

Isthmus of Panama formed 3 million years ago

Ex: snapping shrimp on each side will not mate with one another they snap at each other instead

11.5 Speciation Through Isolation

Grand Canyon speciation of squirrels due to geographic isolation

11.5 Speciation Through Isolation

3. Temporal isolation- when timing prevents mating/reproduction between populations

Ex: The Monterey Pine and the Bishop pine have different pollination periods. (February/April)

Bishop pine

11.5 Speciation Through Isolation

• Field crickets’ reproductive isolation due to temporal isolation

11.5 Speciation Through Isolation

Create your own new species!

• Pick any existing animal

• Please chose one of the three ways speciation occurs– Behavioral– Geographic– Temporal

• Using your imagination, please draw a diagram of how your chosen species might diverge into two new closely related species– Keep it realistic! Ex: Humans can’t become unicorns

11.5 Speciation Through Isolation

11.5 Speciation Through Isolation

11.5 Speciation Through Isolation

VIDEO CLIPS

Humming bird mating dance

Bird mating dances

Bird courtship dance