1. NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION
Chapter 15.1

2. I. CHARLES DARWIN AND NATURAL SELECTION
Evolution: a series of adaptations “over time”
Charles Darwin developed this theory of evolution

3. I. CHARLES DARWIN AND NATURAL SELECTION
A. Fossils Shape and Ideas About Evolution
Fossils form base of evolutionary thoughts

4. I. CHARLES DARWIN AND NATURAL SELECTION
B. Darwin on HMS Beagle
Took this ship (HMS Beagle) on a 5 year scientific journey around the world
Collected fossils at every port along route
Compared each to determine evolutionary relationships
Studies provided the foundation for evolution by natural selection:
Organisms with most favorable traits survive and pass those traits on to their offspring.

5. I. CHARLES DARWIN AND NATURAL SELECTION
C. Darwin in the Galapagos
Galapagos are a group of small islands near the equator
He studied organisms there that are unique to the island, but similar to those elsewhere
Led Darwin to believe that species can “change over time”

6. I. CHARLES DARWIN AND NATURAL SELECTION
D. Darwin Continues his Studies
Darwin observed that the traits of individuals vary in populations. Variations are then inherited.
Breeding organisms with specific traits in order to produce offspring with identical traits is called artificial selection.
Darwin hypothesized that there was a force in nature that worked like artificial selection.

7. I. CHARLES DARWIN AND NATURAL SELECTION
D. Darwin Continues his Studies
Natural selection is 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 traits are less likely to survive

8. I. CHARLES DARWIN AND NATURAL SELECTION
E. Darwin Explains Natural Selection
In nature, more offspring than can survive are produced
In any population, individuals have variations
Over time, those with favorable variations survive and pass those traits on to their offspring
Over time, individuals with variations look entirely different from their ancestors and make up a large portion of the population

9. I. CHARLES DARWIN AND NATURAL SELECTION
F. Interpreting Evidence After Darwin
After much investigation, a majority of scientists have accepted Darwin’s theory of Evolution by natural selection

10. II. ADAPTATIONS: EVIDENCE FOR EVOLUTION
Adaptation: any variation that aids an organisms chance of survival in its environment
Darwin’s theory explains how some of these adaptations may occur

11. II. ADAPTATIONS: EVIDENCE FOR EVOLUTION
A. Structural Adaptations Occur Over Time
adaptations in species develop over many generations

12. II. ADAPTATIONS: EVIDENCE FOR EVOLUTION
A. Structural Adaptations Occur Over Time
Mimicry is a structural adaptation that enables one species to resemble another species
a harmless species has adaptations that result in a physical resemblance to a harmful species
Predators that avoid the harmful looking species also avoid the similar-looking harmless species

13. Syphrid Fly

14. II. ADAPTATIONS: EVIDENCE FOR EVOLUTION
Camouflage: an adaptation that enables species to blend with their surroundings.
Because well-camouflaged organisms are not easily found by predators, they survive to reproduce.

15. Camouflage

16. II. ADAPTATIONS: EVIDENCE FOR EVOLUTION
B. Physiological Adaptations Can Develop Rapidly
Physiological adaptations are changes in an organism’s metabolic processes
Example is penicillin resistant bacteria
Can also be seen in some species of insects and weeds that are pests
Some things develop an “immunity”

17. III. OTHER EVIDENCE FOR EVOLUTION
A. Fossils
Even though fossil record is incomplete, it still gives scientists a good idea of how organisms evolved
For example, the evolution of the camel

18. Camel Evolution

19. III. OTHER EVIDENCE FOR EVOLUTION
B. Anatomy
Homologous structures: structures with common evolutionary origin
same structure, same function, or same in both cases

20. Homologous Structures
Crocodile
forelimb
Bird
wing
Whale
forelimb

21. III. OTHER EVIDENCE FOR EVOLUTION
B. Anatomy
Analogous structures: structures that have NO COMMON ORIGIN, but are similar in function
Ex: insect wings and bird wings

22. III. OTHER EVIDENCE FOR EVOLUTION
B. Anatomy
Vestigial structures: a body structure in a present-day organism that no longer serves its original purpose, but was useful to an ancestor
ex: eyes of blind mole rats, forelimbs of an ostrich, pelvic bone in a baleen whale

23. III. OTHER EVIDENCE FOR EVOLUTION
C. Embryology
Embryo: the earliest stage of growth and development of both plants and animals
There are several similarities between fish, reptile, bird, and mammal embryos
Both have pharyngeal pouches and a tail
This leads people to believe that all have a distant common ancestor

24. Embryology Similarities

25. III. OTHER EVIDENCE FOR EVOLUTION
D. Biochemistry
Nearly all organisms share DNA, ATP, and many enzymes among their biochemical molecules
Scientists compare a specific amino acid sequence, “Cytochrome c” that is present in animals all the way from bacteria to bison (a mammal)

26. Comparison of Cytochrome c
Biochemical Similarities of Organisms
Percent Substitutions
of Amino Acids in
Cytochrome c Residues
Comparison of Organisms
Two orders of mammals
5 and 10
Birds vs. mammals
8-12
Amphibians vs. birds
14-18
Fish vs. land vertebrates
18-22
Insects vs. vertebrates
27-34
Algae vs. animals 57

27. III. OTHER EVIDENCE FOR EVOLUTION
D. Biochemistry
If organisms are biochemically similar, then they have fewer differences in amino acid sequences
If organisms are biochemically different, then they have more differences in their amino acid sequences

28. DON’T FORGET
Today scientists combine all of the following to determine evidence of evolution
Fossils
Anatomy
Homologous, analogous, vestigial structures
Embryology
Biochemical Similarities

29. Question 1
________ is considered to be the fundamental concept of biology.
Genetics
The Modern Theory of Evolution
Artificial selection
Structural adaptation

30. Question 1
________ is considered to be the fundamental concept of biology.
Genetics
The Modern Theory of Evolution
Artificial selection
Structural adaptation

31. Question 2
Breeding organisms with specific traits in order to produce offspring with identical traits is called _________
Natural selection
Adaptation
Mutation
Artificial selection

32. Question 2
Breeding organisms with specific traits in order to produce offspring with identical traits is called _________
Natural selection
Adaptation
Mutation
Artificial selection

33. Question 3 Mimicry and camouflage are NOT examples of _________.
Adaptation
Natural selection
Evolution
Artificial selection

34. Question 3 Mimicry and camouflage are NOT examples of _________.
Adaptation
Natural selection
Evolution
Artificial selection