Transcript 5.3 Evolution

Evolution

Write in complete sentences!
Don’t talk during the Catalyst!
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.
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
 Examples
 There
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
Original
New
shares
98% of
DNA
with
species
original species
New species #2
shares 96% of
DNA with
original species
Speciation

Key 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


Key Point #2: If a population is reproductively
isolated, it may develop into a new species.


Microevolution
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.
