1. Theory of Evolution
“Nothing in biology makes sense EXCEPT in the light of evolution.” Theodosius Dobzhansky

2. Early Evolutionary Thought
James Hutton
Suggested Gradualism
Gradual change over a long period of time leads to species formation

3. Early Evolutionary Thought
Gould and Eldredge
Suggested Punctuated Equilibrium
A successful species may stay unchanged for long periods of time.
Major environmental changes may have caused evolution to occur in spurts

4. Early Evolutionary Thought
Jean-Baptiste Lamarck, 1809
Suggested the Law of Use and Disuse
One Of First Scientists To Understand That Change Occurs Over Time
Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them

5. Early Evolutionary Thought
Lamark
Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime
Said acquired changes were passed to offspring
If body part NOT used, it deteriorated

6. Early Evolutionary Thought
Thomas Malthus
Wrote that human populations are able to increase faster than what the food supply can.
We do not because of disease, war and famine.

7. Early Evolutionary Thought
Charles Darwin
Naturalist aboard the HMS Beagle
Traveled for 5 years around the world
Made observations and collected samples
Eventually landed on the Galapagos Islands where he made several observations that impacted his Theory of “Descent with Modification”.

8. The Galapagos Islands Very Different Climates
Small Group of Islands 1000 km West of South America
Very Different Climates

9. The Galapagos Islands
Animals On Islands
Tortoises
Iguanas
Finches

10. Natural Selection
When visiting on the Galapagos Islands Darwin noticed:
Individuals that have physical or behavioral traits that better suite their environment are more likely to survive and reproduce.
This theory is called Natural Selection

11. Natural Selection Finches
Darwin noticed that there were a number of different types of finches
All finches had physical traits that allowed them to adapt to their environment.
For example if a finch lived on a part of the island that was abundant in flowering plants then the finches beak would be long and thin so that it could drink nectar.

12. Natural vs. Artificial Selection
Natural Selection
A mechanism for change in populations.
Occurs when organisms with favorable variations survive, reproduce, and pass their variations to the next generation.
Organisms without these variations are less likely to survive and reproduce.
Artificial Selection
Breeding organisms with specific traits in order to produce offspring with identical traits

13. Evidence of Evolution Anatomy Homologous Structures
Structural features with a common evolutionary origin
Can be similar in arrangement, in function, or in both.

14. Evidence of Evolution Analogous Structures
Body parts of organisms that do not have a common evolutionary origin but are similar in function

15. Evidence of Evolution Vestigial Structures
Body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor.

16. Evidence of Evolution Embryology
Study of the earliest stage of growth and development of both plants and animals
The embryos of a fish, a reptile, a bird, and a mammal have a tail and pharyngeal pouches
suggest evolution from a distant, common ancestor
Pharyngeal
pouches
Pharyngeal
pouches
Tail
Tail
Fish
Reptile
Bird
Mammal

17. Evidence of Evolution Biochemistry
Provides strong evidence for evolution.
Comparing the same hemoglobin protein in several species reveals a pattern.
Species that share a common ancestor more recently have fewer amino acid differences.

18. Adaptations Mimicry Three major adaptations exist in nature:
A structural adaptation that enables one species to resemble another species.
Because a yellow jacket looks so much like a honeybee it’s predators often mistake it for it’s twin and stay away.

19. Adaptations Camouflage
Adaptation that enables species to blend with their surroundings
Because well-camouflaged organisms are not easily found by predators, they survive to reproduce.

20. Adaptations Physiological Adaptations
Changes in an organism’s metabolic processes
Evolve much more rapidly.
For example, some of the medicines developed during the twentieth century to fight bacterial diseases are no longer effective

21. Antibiotic Resistance
The bacteria in a population vary in their ability to resist antibiotics.
When the population is exposed to an antibiotic, only the resistant bacteria survive.
The resistant bacteria live and produce more resistant bacteria.

22. Formation of a New Species
Speciation
Process by which new species form
Reproductive Isolation
Two populations of the same species do not breed with one another because:
Geographic separation
Difference in mating periods
Other barrier to reproduction.