2. Darwin’s Theory of Evolution
The Origin of Species by Natural Selection

3. Who was Charles Darwin?

4. Journey of the Beagle
1831 – 1836
Darwin was appointed companion to the captain, and self-appointed naturalist.
He spent time ashore collecting plant and animal specimens

5. Ideas that shaped Darwin’s thinking
James Hutton (1788) first suggested that the Earth is millions (not thousands) of years old. Geological processes operate extremely slowly.
Charles Lyell (1833) added that processes can be observed today, and must also explain past events.
Thomas Malthus (1798) observed that more organisms are born than can be supported. Populations are kept in check by famine, war, and disease

6. Jean-Baptiste Lamarck
(1809) theory of the inheritance of acquired traits
- parts used or disused could be changed during an organism’s lifetime, and passed on to offspring.
* First to recognize that organisms change over time; are adapted to their environments, and are descended from common ancestors

7. Alfred Wallace
In 1858 he wrote to Darwin, proposing the same idea of evolution by natural selection
In 1859 Darwin published his theory of evolution by natural selection

8. Darwin in the Galapagos Islands: DIVERSITY

9. DIVERSITY
He saw a great diversity of organisms there.

10. Darwin’s observations:DIVERSITY
68 different species of beetles in a Brazilian rainforest in one day

11. 13 different species of finches on the Galapagos Islands = DIVERSITY

12. Diversity:
It is estimated that there are more than 20 million different species on the Earth today.
99.9 % of all species that have ever lived are now extinct.
How do we explain such diversity, and why have so many organisms disappeared, and so many new ones appeared?

13. Adaptation: any inherited characteristic that increases an organism’s chances for survival
Ground finches: crush seeds with beaks
Cactus finch: eat small insects from flowers or cactus]
Tree finch: feed mainly on insects
Wood pecker finch: uses twigs to pry insects or larvae out

14. Adaptions
Camouflage

15. Adaptions
Mimicry

16. Fitness: the physical traits and behaviors that enable organisms to survive in their environment.
a long neck, a sharp bill and bright blue feet.
elaborate mating ritual : the male raises one blue foot in the air, then the other, as he struts in front of the female.

17. 30 years after the voyage, Darwin published his book (1859): The Origin of Species by Natural Selection
Modern organisms were produced by a process of evolution (change over time)
All organisms have arisen from preexisting organisms
If you look back far enough in time, you will find common ancestors

18. Theory of Natural Selection
Variation: genetic variation in a population
Heritability: genes are inherited
Overproduction: populations produce more organisms than can survive
Reproductive Advantage: Organisms with traits suited for environment survive and reproduce more.
SURVIVAL OF THE FITTEST

19. Artificial Selection Selective Breeding
Breeder chooses traits and breeds organisms with these traits in order to produce desired offspring
Domesticated dogs bred from wolves
Wolves with selected traits bred together over generations to produce different breeds

20. Evolution of Resistance
Ability to break down certain chemicals (antibiotics, pesticides) into harmless molecules
Bacteria have evolved resistance to many antibiotics due to overusage by humans
Organisms with genes to be resistant to chemicals survive and reproduce passing on resistance to their offspring

21. The faster an organism
reproduces,
the faster its populations can
evolve

23. Evidence for evolution: 1. age of the Earth (4.5 bya)
James Hutton (1788): natural processes such as rain, cold, heat, wind, volcanoes, operate slowly, over millions of years
Charles Lyell (1830): forces operating on the Earth can still be seen today.

24. Evidence for evolution: 2. fossils
Fossils: preserved remains of ancient organisms
Show great diversity of organisms that no longer exist
Show gradual and successive changes

25. a. Transitional fossils
Show link between species; have features shared by different species
Archaeopteryx- feathers of bird; teeth, bony tails of reptiles

26. b. Fossil record All fossils of living organisms that have been found
Show ancient species share similarities with modern species
Not all organisms have fossils- incomplete

27. c. Law of Superposition Younger rock layers on top of older
Sedimentary Rock- fossils form easily

28. d. (Radioactive dating)
Uranium 238
4.5 billion years
Potassium 40
1.3 billion years
Carbon 14
5770 years
Radioactive elements decay at a steady rate.
A half-life is the amount of time needed for half of the atoms in a sample to decay.

30. Evidence from living organisms: 3
Evidence from living organisms: 3. embryological vertebrate embryos are similar due to similar genes, common ancestor

32. Structures are similar, functions are different
Evidence from living organisms: 4. Morphological Evidence (Anatomical): a. Homologous Structures
Structures are similar, functions are different
Must have evolved from a common ancestor
structures that are similar in structure but may serve different purposes.
They suggest common origin

33. Organs inherited from ancestors, but having no apparent function
Evidence from living organisms: 4. Morphological evidence: b. vestigial organs
Organs inherited from ancestors, but having no apparent function
Organs that appear in the embryo but are lost later in development
Organs that have no apparent function, or that may appear in the embryo but are lost later in development

34. Evidence of Evolution: 4. Morphological evidence:. c
Evidence of Evolution: 4. Morphological evidence: c. Analogous Structures
Structures with the same function, but different structures
Not closely related animals
Environment controls adaptations

35. Evidence in living organisms: 5. Biochemisty: chemical compounds
All living organisms have some compounds in commmon
DNA and ATP
RNA
Cytochrome C

36. Evidence in living organisms: 6. Geographic Distribution
Organisms in different parts of the world are very similar
Due to separation of continents and organisms evolving adaptations to their environment

37. Evidence in living organisms: 6. Geographic Distribution