Speciation Lesson

Speciation
Mrs.Graham-Jones

DO Now: Progress Learning: Bio1A.1/4.6


5 minutes

Engage

 Country Cousin/City Cousin Activity

What happens when a population or group of living things is divided into

two separate groups in two separate environments? To understand what

goes on, think about someone who lives in another part of the United

States or in another country.

Working with a partner, list everyday things that this person

encounters that you don’t. For example, does he or she eat different kinds

of food? Does he or she live in a climate different from yours?

Explore

Speciation Activity

https://whs.rocklinusd.org/subsites/Biology/documents/Biology/Unit%207/Speciation%20Activity.pdf

*Groups of 4

Open Ended

Answer Question 1 and 2

Lesson Agenda

​_Isolating Mechanisms
1. Behavioral
2. Geographic
3. Temporal

_Speciation in Darwin's Finches
1. Founders arrive
2. Geographic isolation
3. Changes in gene pools
4. Behavioral isolation
5. Competition and continued Evolution

When two populations are separated by geographic barriers such as rivers, mountains, tepuis (shown), or bodies of water, geographic isolation occurs.

Geographic Isolation

If two populations that were once able to interbreed evolve differences in courtship rituals or other behaviors, behavioral isolation can occur.

Behavioral Isolation

Isolating Mechanisms

​Temporal Isolation
happens when two or more species reproduce at different times.

Speciation Darwin's Finches

Founder's Effect
The theory remains that the population on the islands is under the influence of the founder effect.

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Founders Arrive

Different species of these birds live on different islands in the Galápagos archipelago, located in the Pacific Ocean off South America. The finches are isolated from one another by the ocean. Over millions of years, each species of finch developed a unique beak that is especially adapted to the kinds of food it eats.

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Geographic Isolation

On the Galápagos, finches evolved based on different food sources — long, pointed beaks served well for snatching insects while broad, blunt beaks work best for cracking seeds and nuts.

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Changes in Gene Pool

​The production of different mating songs by these beaks is behavioral isolation that occurs indirectly from the adaptations.

Behavioral Isolation

When two species compete for the same limiting resource the reduction of the niche overlap may lead to evolutionary changes in both species.

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Competition and Continued Evolution

Multiple Choice

Answer the question using the image provided!

• A

• B

• C

• D