1. Theory of Evolution
Chapter 16

2. Idea of Evolution Charles Darwin (1809-1882) English naturalist
Took a trip around the world on a ship called H.M.S. Beagle
Mostly fascinated with the Galapagos Islands
Best known for his theory of evolution by natural selection

3. Darwin’s Journey Began in 1831
Sailed on a ship called the H.M.S. Beagle
Five year voyage sailing around the coast of South America and Australia

4. Observations Aboard the Beagle
Darwin collected 68 species of beetles
Wrote about the different characteristics of habitats and species that live there
Species vary globally
There are similar organisms around that world with similar ecological habitats
Ex: Rhea birds in S. America and ostriches in Africa

5. Observation Aboard the Beagle
Species vary locally
Related animals species often occupy different habitats within a local area
Ex: Tortoise shell shape among Galapagos Islands

6. Observation Aboard the Beagle
Species vary over time
Some fossils of extinct animals were similar to living species
Ex: Armadillo fossils compared to modern day armadillos

7. Darwin’s Findings Galapagos Islands
Groups of animals vary from island to island
Ex: tortoises and finches on each island resemble each other but differ in the shape and function of their shells and beaks
Darwin believed these unique animals all came from a common ancestor and they changed/adapted to their environment

8. Idea of Evolution Evolution
Development of new types of organisms over time
Heritable change in the characteristics within a population from one generation to the next

9. Ideas of Darwin’s Time
Scientists thought all species were permanent and unchanging
The Earth was believed to only be a few thousand (not billions) of years old
During Darwin’s time, new research was being done to figure out the geology of the Earth

10. Ideas that Influenced Darwin
James Hutton was a geologist in 1700’s
Made connections between mountains, valleys, and layers of rock
Believed the Earth was older than thousands of years -- a time so old for the human mind to image
The Earth changes very slowly and some layers can accumulate as the environment is changing

11. Ideas that Influenced Darwin
Charles Lyell was a English geologist that believed the Earth’s surface continues to change
He explained that past processes that occurred are still occurring now
Ex: Volcanoes erupted in the past and still today
Published a great work called Principles of Geology in that built on the work of Hutton
Darwin read this book while on his journey around the world

12. Ideas that Influenced Darwin
Jean-Baptiste Lamarck
French naturalist that supported the idea that populations of organisms change over time

13. Ideas that Influenced Darwin
Proposed two hypotheses: Called Theory of Acquired Traits
Organisms could change during their lifetime by using or not using selected parts of the body
Individuals could pass these acquired traits on to their offspring
Ex: Giraffes could lengthen their neck by stretching over a period of time to get the height they needed to eat and survive and then pass the longer neck trait to their offspring

14. Ideas that Influenced Darwin
Thomas Malthus was an English economist in the 1790s
Reasoned that if the human population grew continuously, there would not be enough resources for everyone
His reasoning explained why plants and animals produced more a high amount of offspring since a portion will not survive due to environmental factors
Ex: Maple tree produces thousands of seeds each summer
Ex: Oysters produce millions of eggs each year with the understanding that only a fraction will survive

15. Darwin’s Ideas
Around the same time Darwin and Wallace formed theory to explain evolution
Darwin was able to publish his book first called On the Origin of Species in 1858
Book explained how evolution occurs by means of natural selection
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16. Artificial Selection Darwin studied animal breeders
Farmers would select to breed only trees with the largest fruit, or the cows that produce the most milk
Darwin called this process artificial selection
Nature provides the variations, and humans select hose they find to be useful and allow them to breed and pass on traits to offspring

17. Evolution by Natural Selection
Mechanism from descent with modification
1. Struggle for Existence
Organisms produce more offspring than can survive
Ex: dogs give birth to a litter of puppies, while only a majority survive
2. Variation and Adaptation
Traits vary within a species and their environment called adaptations
These adaptations help increase ability to survive
Ex: Mimicry with coral snake and scarlet snake

18. Natural Selection (cont’d)
3. Survival of the Fittest
Organisms best adapted for an environment will survive best and reproduce
The ability for an organism to reproduce and pass on adaptations
Ex: camouflage to help hide from predators
4. Natural Selection
Process by which organisms with variations most suited to their local environment survive and leave more offspring
Organisms choose their mate based on desired traits
Ex: beetles that are not eaten because of their color, will reproduce

19. Common Descent
Idea that every species must have descended by reproduction from pre-existing species that arrange over time
Ex: finch beaks at Galapagos
All species – living and extinct – are descended from ancient common ancestors

20. Transitional Species
Organisms with features that are between hypothesized ancestors

21. Age of the Earth & Fossils
Noted that fossils of extinct animals resembled living species
Relative Age
Age compared to other fossils in order of old to young
Absolute Age
Using radioactive dating to get actual number age

22. Age of the Earth and Fossils
Geologists are certain based on evidence via radioactive dating to indicate the Earth is about 4.5 billion years old
Fossils
Remains of an organism that died long ago
Many fossils form a series that can trace back to an ancient extinct ancestor
Superposition
Idea that strata form in layers where the layers closest to the top are the younger than below

23. Anatomy and Embryology
Anatomy: study of the body
Embryology: study of development
Homologous structures
Anatomical structures that originated from the same common ancestor
Ex: bones in arms of humans, penguins, alligator and bat
Related structure but function may differ

24. Anatomy and Embryology
Analogous Structures
When structures have similar function, but did not develop the same way
Ex: wings of bat vs. bird
Vestigial Structures
Organs that no longer serve a function in an organism
Ex: human tail bone, appendix

25. Anatomy and Embryology
Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor
Many animals look similar during development and produce homologous tissue

26. Genetics and Molecular Biology
At the molecular level, the genetic code and homologous molecules provide evidence of common descent

27. Phylogeny Relationships among groups of organisms
Can make a “tree” of animals evolved
Trunk of the tree would represent species that are closely related
Branches represent a separate population or lineage

28. Evolution in Action
Biologists tested the hypothesis by comparing DNA from the various species
DNA evidence supported hypothesis 2 that each lizard evolved independently on each island
Convergent Evolution
Process by which different species evolve similar traits
Ex: twig-dwelling species came from different ancestors but evolved similar adaptations to their environment

29. Divergence & Radiation
Divergence evolution
Process by which the descendants of a single ancestor diversify into species that each fit different parts of the environment
Ex: All breeds of dog share a common ancestor with wolves

30. Divergence & Radiation
Adaptive Radiation
Pattern of diversity when a new population in a new environment undergoes divergent evolution

31. Coevolution Evolution is on-going and many species may evolve together
When two or more species have evolved adaptations to each other’s influence
Ex:
Predator/Prey Interactions
Introduction of new species
Creating antibiotics