NATURAL SELECTIONNATURAL SELECTION

How do we organize the How do we organize the diversity of life?diversity of life?

How do we explain:

• great diversity of organisms?

•organisms that are well-adapted to their environment?

•similarities and relationships of organisms (all use same basic genetic information)?

Jean-Baptiste Lamarck (1744-1829)

Inheritance of Acquired Characteristics – Traits developed during your life can be given to offspring.

Theory of Use and Disuse – Genetic traits can be developed.

Example – Blacksmith and bigger biceps

Example – Giraffe and longer neck

Problem – How do you account for any variety in giraffes?

What about those who don’t have long necks?

Did trees all of a sudden get taller?

What if someone gets a tattoo?

Loses a finger?

Dyes their hair?

Inheritance of Acquired Characteristics – WRONG! Traits developed during your lifetime cannot be passed on. You cannot will yourself to have new traits.

Charles Darwin (1809-1882)

Voyage of the H.M.S. Beagle – (1831-1836)

Among other observations, saw

finches on the Galapagos

Islands off the coast of South

America. These finches had

been seen nowhere else in the

world, but resembled those on

South American coast. How did

they become so well-suited to

their environment?

Darwin Video – http://www.teachersdomain.org/resources/tdc02/sci/life/evo/lp_darwin/index.html

Theory of Natural Selection

4. Differential survival and reproduction – Those that live, reproduce and pass on traits.

Example #1 – Speedy Rabbits

# o

f ra

bb

its

Slow Fast

What will this graph look like if a predator is introduced into the rabbit’s habitat?

1. Genetic Variation – Each organism has unique DNA sequence and traits.

2. Overproduction of offspring – More kids are produced than can survive.

3. Struggle for existence – Kids compete for limited resources (food, shelter, mates).

PBS video - natural selection (6:41)

Example #2 – Peppered moth. Two different colors – light and dark. How many moths do you see in each picture?

Prior to 1850 most had light-colored wings

After 1850 most had dark-colored wings.

WHY?

DOES EVOLUTION HAPPEN WITHIN ONE GENERATION?

EXAMPLE: A LIGHT-COLORED MOTH IS MOVED TO AN

AREA WITH SOOT COVERED TREES. CAN THIS

INDIVIDUAL MOTH EVOLVE?

Evidence to support Theory of Evolution and Natural Selection

1. Comparative Anatomy – Bones have similar patterns

Fossil Video (7:00)

2. Molecular Biology – all organisms use same A, T, C, G, but

different order. Sequence can acquire mutations which can

be passed on to next generation. Mutations can result in different traits.

Video – includes UW-Madison researcher, Dr. Sean Carroll(7:00)

3. Selective breeding – Humans have been performing

natural selection experiments for centuries using “artificial selection”.

TEOSINTE AND CORN Artificial Selection of Wild Mustard

Video ClipsVideo ClipsClassification of Species (2:09)Classification of Species (2:09)

Natural Selection - Darwin (6:49)Natural Selection - Darwin (6:49)

PBS - Adaptation - Hummingbirds (6:39)PBS - Adaptation - Hummingbirds (6:39)

PBS - Adaptation - Mantis camouflage (:58)PBS - Adaptation - Mantis camouflage (:58)

PBS - Molecular Evidence (4:47)PBS - Molecular Evidence (4:47)

PBS – Salamander Migration (3:21)PBS – Salamander Migration (3:21)

Using What You Have LearnedUsing What You Have Learned

How would Darwin How would Darwin use his Theory of use his Theory of Natural Selection to Natural Selection to explain the insect explain the insect seen in this seen in this videovideo??