1. Natural Selection

2. False – no perfect organism False ~ results from genetic variation
True or False
Evolution is a theory about the origin of life.
False
2. Organisms are always getting better through evolution
False – no perfect organism
3. Natural selection involves organisms trying to adapt
False ~ results from genetic variation
4. Evolutionary theory is invalid because it is incomplete and cannot
give a total explanation for the biodiversity we see around us.
False ~ All scientific theories are works in progress . As new evidence is discovered, theories are revised or even disproven

3. Important Vocabulary
1. Species: A group of organisms whose individuals can breed together to produce fertile offspring.
2. Population: A localized group of individuals belonging to the same species.
Examples: a herd of bison
3. Evolution: A slow change in a population over time.
4. Adaptation: any structural or physiological change that gives an organism an advantage in the environment.
Examples: stingers, wings, camouflage, maintaining a constant body temperature, containing a poisonous chemical

4. Charles Darwin explained how Natural Selection could cause a population to adapt & change over time. (“population” will change -not an “individual”)

5. Route of Darwin’s 5 Year Trip
Galapagos Islands
Darwin spent a lot of time and collected a lot of specimens from the Galapagos Islands.

6. Charles Darwin: An Unlikely Evolutionist
Who was Charles Darwin?
1809: English naturalist
Went on a 5 year voyage on the HMS Beagle as an unpaid scholar
Collected plants & animals during journey
Darwin did not set out to develop a theory of evolution
Observations and specimens collected helped Darwin formulate his theory of evolution
Charles Darwin

7. Darwin’s Observations
In Argentina, Darwin saw earthquakes raising the earth several feet
Shells of marine animals found far inland & at great heights in Andes Mts
Fossils of huge sloths & armadillo-like animals (both extinct) – similar to modern forms
Animals on Galapagos were similar but not same as those on mainland S. America & Antarctica
Galapagos penguin
14 inches tall
5 lbs
Eat small fish & sardines
Nests in burrows
Chinstrap penguin
28 inches tall
9-14 pounds
Eat small fish & krill
Build nests out of small stones

8. Darwin’s Observations on the Galapagos Islands
Finches on Galapagos resemble mainland finch, but there were more types on the islands

9. The Work of Lyell Influenced Darwin’s Ideas
Charles Lyell – English geologist
1830: On the Principles of Geology
Natural forces & processes that shaped ancient Earth are the same forces acting on Earth today.
EX: Rain erodes mountains & molten rock pushes up to create new ones.
Earth’s geologic features formed as a result of gradual processes
Must take millions of years to change geography.
2. Darwin read Lyell’s work while on his voyage & agreed with Lyell’s conclusions

10. Malthus: Organisms have more offspring than nature can support

11. The Work of Malthus Influenced Darwin’s Ideas
Slide # 12
The Work of Malthus Influenced Darwin’s Ideas
1798: Thomas Malthus --Economist
Essay on the Principle of Population
Said that plants and animals tend to have more offspring than nature can support
Food production increase at a slower rate than population
Darwin read Malthus’s essay after he returned from his voyage
Darwin concluded that all organisms produce more offspring than the population can support
Thomas Malthus

12. Lamarck’s Theory of Use and Disuse
1801: Theory of Inheritance of Acquired Characteristics
“Theory of inheritance of acquired characteristics” & “Use and disuse”
If an organism changes in order to adapt to its environment, those changes are passed on to offspring.
(We now know that individual organism cannot change or adapt to their environment)
Said that changes in organisms occur to help an organism reach perfection.
Problem?: there are NO perfect organisms

13. Example of Lamarck’s Hypothesis

14. Darwin explained Evolution by Natural Selection
Slide # 15
Darwin explained Evolution by Natural Selection
1859: Darwin published On the Origin of Species
Proposed that natural selection was the mechanism for evolution.
Individuals vary in one or more traits & there can be slight differences in their ability to survive & reproduce.
Nature selects those individuals w/ favorable traits to leave more offspring that are better suited (FIT) for their environment.
Published 25 years after Darwin wrote it!

15. Evidence that Supports Evolution: Fossil Record
Youngest, most complex fossils
Oldest, simplest fossils
1. Fossil: preserved remains (bones, teeth, shells) or evidence (imprint or footprint) of ancient organisms.

16. Geographic Distribution of Living Species
Convergent:
Con-: together, with, jointly
Verge-: to move or incline in a certain direction
1. Biogeography: the geographical distribution of species in relation to geography and other species
2. Influenced by continental drift
3. Leads to convergent evolution: the appearance of apparently similar structures in organisms in different lines of descent

17. Homologous Structures
Homo- : same, common
-logos: relation, reasoning, computation
-ous: possessing, full of
Homologous structures: similar structures; different functions
Structures develop from same clump of embryonic cells
Provides evidence that four-limbed vertebrates descended from a common ancestor.

18. Pelvis & femur bones are vestigial in whales
Vestigial Structures
Vestigial
Vestige: a mark, trace, or sign
-al: having the form or character
Pelvis & femur bones are vestigial in whales
Vestigial structures: structures or organs that are reduced in size; do not seem to serve a useful function

19. Similarities in Embryology
Hollow dorsal nerve cord
Notochord
Pharyngeal pouches
Postanal tail
The embryos of vertebrates are very similar during early development.
2. The same groups of embryonic cells develop in the same order and in similar patterns to produce tissues & organs.
3. Implies common genes are involved

20. Post Darwin: DNA Evidence Supports Evolution
We can compare DNA sequences to which are most closely related
We can compare amino acid sequences to which are most closely related
Why didn’t Darwin use DNA evidence in developing his theory?