1. Evolution Evidence and Theory
Chapter 14
Honors Biology

2. Early Biological Though
Heavily influenced by theology
All organisms were created simultaneously
Each distinct life-form was permanently fixed and did not change over time

3. Evolution- Is it true?
A genetic change within a population over time!
Population- interbreeding single- species group

4. Fossils- Documentation
Fossil - trace of a long-dead organism.
Sedimentary rock - formed by dust, sand, or mud deposited by wind or water over dead organism
Formed by hard body parts of an organism— shell, bones, teeth, or woody stems
Hard minerals replace the tissue of the organism leaving rocklike structures

5. Sedimentary Rock

6. Fossils Mold – imprint in rock in the shape of an organism
limestone
Cast – forms when molds are filled with hard minerals
Mold
Cast

7. Limestone Limestone – most abundant , non-classic sedimentary rocks.
Limestone is produced from the mineral calcite (calcium carbonate) and sediment.
Chalk is another type of limestone that is made up of very small single-celled organisms.

8. Robert Hooke
He concluded that fossils are remains of plants and animals
He mostly studied “petrified wood” with the aid of the microscope
He hypothesized that living organisms had somehow been turned to rock

9. Petrified Wood Wood that has turned to stone!

10. Non-evolutionary Explanations
Catastrophism
Georges Cuvier ( )
High numbers of species were created originally
Series of catastrophes produced rock layers
destroyed many species, preserving some as fossils
Modern day species are the survivors of these catastrophies

11. Uniformitarianism
James Hutton ( ) and Charles Lyell ( )
Developed theory of uniformitarianism
Geologic change resulted from slow, continuous actions similar to those at work today

12. Distribution of Fossils
Nicolaus Steno ( )
“law of superpositon” – states that the top layers of stratum contain the youngest fossils while the lower ones are older
Determine the “relative age” of a fossil
“absolute age”- age in years determined by radiological evidence

13. Succession of Forms
Mass extinctions – brief periods during which large numbers of species disappears.
Resulted from drastic changes in the environment, volcanic activity or collisions with asteroids (may have blocked sunlight for long periods of time and decreased temp.)

14. Biogeography
Biogeography – is the study of the geographical distribution of fossils and of living organisms.
A comparison of fossil types with types of living organisms in the same geographic area
shows that new organisms arise in areas where similar forms already lived.
Ex: armadillos in North & South America where glyptodonts lived in the past.

15. Armadillos

16. Glyptodonts

17. Scaphognathus crassirostris Lab Fossil

18. Theories of Evolution I. Lamarck’s Explanation:
He hypothesized that acquired traits were passed on to offspring.
Proposed that similar species descended from a common ancestor (fossil records)

19. Acquired Trait It’s not determined by genes!
Occurs during an organism’s lifetime
result of the organism’s experience or behavior.
Ex: 1. Muscles on a body builder
2. Giraffe’s necks did not get longer by trying harder and harder to reach tall trees- Genetic

20. Beginning of Modern Evolutionary Theory
II. Charles Darwin ( ) & Alfred Wallace ( )
Darwin & Wallace announced their hypotheses at the same time
Darwin’s name became more associated with evolution The Origin of Species published

21. Darwin’s Voyage on the Beagle
Sailed in 1831 for five years
Collected specimens and kept careful records of his observations
Sailed to South America (Galapagos Islands) and the South Pacific

22. Voyage of the Beagle

23. Darwin’s Findings
Collected 13 similar but separate species of finches.
Each finch species had a distinctive bill for specialized food source.
Implied that the finches shared a recent common ancestor

24. Darwin’s Finches

25. Darwin’s Findings

26. Darwin’s Theories TWO THEORIES;
1. DESCENT WITH MODIFICATION – The newer forms appearing in the fossil record are actually the modified descendants of older species
Organisms similar to each other- common ancestor
Organisms that are dissimilar -share a more remote ancestor

27. 2. Modification by Natural Selection
MODIFICATION BY NATURAL SELECTION – states HOW evolution occurs.
Organisms best suited to their environment reproduces more successfully than other organisms
Leaf tailed gecko

28. Based on 4 postulates 1. Individual members of a population differ
Postulate- something taken as self-evident 
1. Individual members of a population differ
Variations arise purely by chance resulting from random mutations in DNA
2. Variations are passed from parent to offspring
3. Some individuals in a population survive and reproduce successfully but others do not
4. Individuals with advantageous traits survive longest and leave the most offspring- natural selection

29. Adaptation- Adaptive advantage
A population of organisms adapt to their environment
# of genes for favorable traits increases
Fitness- a single genetic organism’s contribution to the next generation’s survival
A well adapted organism will reproduce successfully and have a high fitness

30. High Fitness? Low Fitness?

31. High Fitness? Low Fitness?

32. High Fitness? Low Fitness?

33. High Fitness? Low Fitness?