1. Evolution

2. Evolution Theory Evolution- process of change over time
Theory of Evolution- states that existing forms of life have evolved from earlier forms over a long period of time
Macroevolution- large changes
that occur between species
Mircoevolution- small changes within a species

3. Proof Fossil Record Comparative Anatomy Comparative Embryology
Comparative Biochemistry
Comparative Genetics

4. Fossil- any remains or trace of a once living organism
Fossil Record
Fossil- any remains or trace of a once living organism
b Fossils show that many organisms that lived long ago are extinct
Extinction- when the last members of a species die (can be caused by environmental changes such as floods, earthquakes, etc)
D. Formation of fossils
1. Preservation of Whole Organisms -An organism may be preserved and protected against decay by being trapped in amber (sap from trees), frozen in ice or buried in tar
2. Preservation of Hard Parts
Soft parts of an animal have decayed away, but the bones or shells have been preserved

5. Footprints in mud, which later harden to form fossils
Fossils in the form of tubes and tunnels in rock that hardened after the animals had burrowed through the materials

6. 2. Comparative Anatomy
Some body parts show similarities in structure and development (homologous structures)
EX: the arms of humans, the flippers of whales, the arms of cats and the wings of bats and birds all have the same arrangements of bones

7. 3. Comparative Embryology
The development of embryos of organisms that are quite different in
the mature form often
show similarities in
their early stages of
development

8. 4. Comparative Biochemistry
Biochemical compounds in different species can be compared
The closer the relationship between two species, the closer the similarities of amino acid sequences in their proteins. Organisms of different species have similar proteins!
5. Comparative Genetics
All living cells use information
coded in DNA.
The genetic code is nearly
identical in almost all organisms
(bacteria, yeasts, plants, fungi
and animals)
All organisms evolved from common
ancestors that shared this code

9. Historical Development
Jean-Baptiste Lamarck
Proposed that changes in species occurred basically as the result of a striving of organisms for improvement
Acquired Characteristics- a trait acquired during the lifetime of an individual can be transmitted to its offspring

10. It was later discovered that:
Acquired characteristics cannot be inherited
EX: he cut off tails of mice in many successive generations and no changes in the length of the tail was observed

11. 3. Theory of Natural Selection
Charles Darwin explained how organisms evolved over long periods of time through descent from common ancestors
Proposed that evolution occurred as a result of natural selection
Natural selection- organisms
with favorable variations (traits)
are better able to survive and
reproduce

12. Testing Natural Selection
Studied finches on the Galapagos islands and found differences between the finches that were located on the islands
Darwin hypothesized that finches descended from a common ancestor
Noted that several finch
species have beaks with
different sizes and shapes
Beaks are used for food
Natural selection had proposed that finches with beaks (small, medium or large) that were able to eat certain food (depending on environment) would survive, reproduce and pass their genes to the next generation of offspring

13. Evolution by Natural Selection
Conditions where natural selection occurs:
Overproduction- within a population, more offspring are produced than can survive because of limitations of living space and food supply
Competition- individuals of each generation compete for available food and for opportunities to mate and reproduce
Variation- differences amongst a species that are inherited (can be beneficial or detrimental to survival)
Some individuals are able to survive better than others due to variations in characteristics

14. Survival of the Fittest
Those individuals better fitted to survive are more likely to live long enough to reproduce and pass the favorable traits to their offspring
Transmission of Favorable Variations
The offspring of the fittest individuals will inherit the favorable variations that enabled their parents to survive and reproduce
Evolution of Species
The accumulation of favorable
variations will gradually
lead to the appearance
of new species better adapted
to the environment

15. Modern Theory of Evolution
Other Sources of Variation
Random mutations- changes in
genetic material of a cell
Sexual reproduction by segregation
and recombination of genes
(heredity units on chromosomes)
Genetic recombination- a shuffling of genes in an
organism’s offspring occurs.
Crossing over- chromosomes
exchange genes during meiosis

16. Genetic Recombination
Crossing Over

17. Results of Genetic Variation
Structural Changes-variations lead to structural changes
EX: Polar bear has thick fur that protects against cold environment
2. Behavioral Change- specific behaviors in a species that result in greater reproductive success.
EX: Fighting among the males of a
walrus population enhances mating
with many females.

18. Adaptation- any characteristic that increases an organism’s ability to survive and reproduce in its environment
Camouflage- the organism blends into the environment
Warning Coloration- the colors of the animal actually make it easier to see
Mimicry- the organism is protected
from its enemies by its resemblance
to another species
EX: Monarch and Viceroy butterflies

19. An organism can not change its DNA and therefore can not change its adaptations
Traits can enable survival or prevent an organism from surviving
Environmental changes can favor survival of one individual over another
EX: Camouflage of dark peppered moth in a sooty environment enabled their survival compared to light peppered moth; light peppered moths could not change their color to blend in

20. Changes in Species
Fossil record shows that over time, species have changed and new species have appeared
EX: insect variants resistant to insecticides such as resistant roaches, mosquitoes and flies
EX: Industrial melanism, the appearance of dark-colored insects that blend against backgrounds blackened by soot (peppered moths)
EX: Bacterial resistance to
antibiotics

21. Antibiotic-Resistant Bacteria
When a population of millions of bacteria is exposed to an antibiotic, there is a chance that a few bacteria might have a gene that makes them resistant to that antibiotic.
The bacteria with the resistant gene would survive.
These few bacteria would reproduce giving rise to a new population of
bacteria that are now
resistant to the drug.

22. Now let’s complete the “peppered moth LAB”
A NATURAL SELECTION EXAMPLE