Evolution

Spider monkeys use their claws to climb trees and reach food. There is not enough food for everyone. A spider monkey population has some monkeys with large claws, and other monkeys with smaller claws. What is the environmental pressure exerted on this

population? What will happen to the frequency of the gene that

produces large claws? Why? Is having small claws an adaptation? Why or why not? Is having large claws an adaptation? Why or why not?

Write in complete sentences!

Don’t talk during the Catalyst!

Objectives

By the end of today all SWBAT…

Define species Describe how evolution leads to new species

Agenda

Catalyst Review Microevolution

Two Practice Problems Speciation/Macroevolution

What happens if you cross a mouse and mango?

Concept map Exit Question

Microevolution

Key Point #1: Natural selection causes microevolution Microevolution = change within a species

ExamplesThere are white and brown bears at the

North Pole. The white bears live longer and have more kids. Eventually, all bears are white.

Some eagles have claws, others don’t. The eagles with claws live longer and have more kids. Eventually, all eagles have claws.

Practice 1

Peppered moths are white with black spots. They live on light-colored trees, and are hunted by birds. Occasionally, mutants were born that were all black. One day humans build a nearby factory that covers all the trees with black dirt and soot! What will happen to the gene for spotted moths?

Why? What will happen to gene for black moths? Why? Over the course of 1000 years, how will the

moths evolve?

What is a species exactly?

Species = a group of organisms that can produce fertile offspring with each other.

They cannot breed,

therefore, they are not the

same species

Reproductive Isolation

Key Point #2: Reproductive isolation = something that prevents two organisms from making fertile offspring

Mouse and Mango!

Make a Hypothesis

Remember, microevolution is small, heritable changes in a population of organisms.

But what do you think would happen if many traits changed…

Over and over again, for millions of years…

Evolution

Key Point #3: If enough changes build up, and there is reproductive isolation, then speciation may occur. Speciation = formation of new

species. Also called macroevolution

Original species

New species shares 98% of DNA with

original species

New species #2 shares

96% of DNA with original

species

Original species

Newspecies

Concept Map

Key Point Wrap-Up

Key Point #1: Natural selection causes microevolution Microevolution = change within a species

Key Point #2: Reproductive isolation = something that prevents two organisms from making fertile offspring

Key Point #3: If enough changes build up, and there is reproductive isolation, then speciation may occur. Speciation = formation of new species.

Also called macroevolution

Exit Question

A horse and a donkey cannot mate to produce fertile offspring—are they in the same species?

What is reproductive isolation? Describe how reproductive

isolation could cause speciation (macroevolution) using at least TWO complete sentences.