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? EXPLAIN how you know.
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
Mouse and mango ooh la la 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 In a population of beetles, some are
green and some are brown. They live in the dirt and are hunted by birds flying overhead. What will happen to the green beetles?
Why? What will happen to brown beetles?
Why? Over the course of 1000 years, what
will happen?
Practice 2 Peppered moths are white with black spots.
They live on light-colored trees. Occasionally, mutants were born that were all black. One day, humans build a nearby factory that covered 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, what will
happen?
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
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…
Mouse and Mango!
Evolution Key Point #2: If a population is
reproductively isolated, it may develop into a new species. 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
SpeciationKey Point #3: Speciation requires reproductive isolation Reproductive isolation = something that prevents two organisms from making children
Independent Practice Evolution Worksheet
Complete sentences
When you are done, work on your Skittles lab
Key Point Wrap-Up Key Point #1: Natural selection
causes microevolution Microevolution
Key Point #2: If a population is reproductively isolated, it may develop into a new species. Speciation
Key Point #3: Speciation requires reproductive isolation. Reproductive isolation
Exit Question A horse and a donkey cannot mate to
produce fertile offspring. Are they in the same species?
Describe what reproductive isolation is.
Describe how reproductive isolation could cause speciation (macroevolution) using at least TWO complete sentences.
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