Set up Cornell Notes on pg. 29 Topic: 11.5 Speciation Through Isolation Essential Question: How did geographic isolation affect the diversity Darwin observed in the Galapagos finches? Why are the flash patterns of fireflies considered to be behavioral isolation? 11.5 Speciation Through Isolation 2.1 Atoms, Ions, and Molecules How did geographic isolation affect the diversity Darwin observed in the Galapagos finches? Why are the flash patterns of fireflies considered to be behavioral isolation?

KEY CONCEPT New species can arise when populations are isolated.

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

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

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

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

Grand Canyon speciation of squirrels due to geographic 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

Field crickets’ reproductive isolation due to temporal 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

VIDEO CLIPS Humming bird mating dance Bird mating dances Bird courtship dance