Slide 1

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest


Slide 2

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest


Slide 3

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest


Slide 4

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest


Slide 5

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest


Slide 6

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest


Slide 7

Evolution Happens
Rock Pocket Mouse

Rock Pocket Mouse
• Sandy colored mouse
– 2 copies of same allele (sandy)

• Black colored
– At least one copy of black allele

Mutation Rate
Mutation rate = 2 mutations per 109 sites in DNA
Possible sites = 10
Diploid organism has 2 copies of the gene
Now multiply it all: 2 x 10-9 x 2 = 4 x 10-8
But what does this number mean?

This Number Means Something
4 x 10-8 can also be seen as a fraction 1/25,000,000
• So 1 out of every 25 million mice will have a
mutation that gives rise to a black coat
• Wow, sounds like this will never happen!
• We don’t have all the info yet
– We need to factor time and breeding into the
equation

Determining the Rate of Change
• Reproductive rate = 5 offspring per year
• Population has 5000 breeding females
• Calculate the total offspring per year
5 x 5000 = 25,000 per year

• Hmm, that number still doesn’t mean much to
me
• Remember 1/25,000,000? Multiply!
– 1/25,000,000 x 25,000 = 1/1000
– That’s one black mouse every 1000 years

Rate of Change and Time
• Big deal, one black mouse every thousand years.
How’s that going to do anything for evolution?
• The lava flows in this mouse’s habitat are
17,000,000 years old
• That means this variation could have happened
1700 times since those flows appeared!
• Only once was needed

Natural Selection
• Natural selection took care of the rest