1. Principles of Evolution
Chapter 10
Principles of Evolution

2. Early scientists proposed ideas about evolution.
Evolution is the biological change process by which descendants come to differ from their ancestors.
A species is a group of organisms that can reproduce and have fertile offspring.

3. There were many important naturalists in the 18th century.
Linnaeus: classification system from kingdom to species
Buffon: species shared ancestors rather than arising separately
E. Darwin: more-complex forms developed from less-complex forms
Lamarck: environmental change leads to use or disuse of a structure

4. Theories of geologic change set the stage for Darwin’s theory.
The age of the Earth was a key issue in the early debates over evolution
Common view was that Earth was created about 6000 years ago and the Earth nor its species have changed

5. There were three theories of geologic change. catastrophism
gradualism
uniformitarianism

6. The theory of catastrophism states that natural disasters such as floods and volcanic eruptions have happened often during Earth’s history.
Shaped landforms and caused species to become extinct

7. James Hutton proposed that changes in landforms were the result of slow changes over a long period of time – principal of gradualism

8. Uniformitarianism is the prevailing theory of geologic change.(Lyell)
The geologic processes that shape Erath are uniform through time

9. Darwin’s observations

10. Charles Darwin the Naturalist

11. Charles Darwin and his Voyage on the Beagle
Born Feb. 12, 1809
Joined Crew of HMS Beagle, 1831
Naturalist
5 Year Voyage around world
Avid Collector of Flora & Fauna
Astounded By Variety of Life

12. A reconstruction of the HMS Beagle sailing off Patagonia.

13. Darwin returned 5 years later in 1836
Darwin Left England in 1831
Darwin returned 5 years later in 1836

14. HMS Beagle’s Voyage

15. The Galapagos Islands Volcanic islands off the coast of South America
Very different climates
Island species varied from mainland species & from island-to-island species
Animals On Islands Unique
Tortoises
Iguanas
Finches

16. Darwin observed differences among island species.
Variation is a difference in a physical trait.
Galápagos tortoises that live in areas with tall plants have long necks and legs.
Galápagos finches that live in areas with hard-shelled nuts have strong beaks.

18. The Finches Finches on the islands resembled a mainland finch
More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…)
Finches had different types of beaks adapted to their type of food gathering

20. An adaptation is a feature that allow an organism to better survive in its environment.
Species are able to adapt to their environment.
Adaptations can lead to genetic change in a population.

21. Darwin observed fossil and geologic evidence supporting an ancient Earth.
Darwin found fossils of extinct animals that resemble modern animals.
Darwin found fossil shells high up in the Andes mountains.

22. He saw land move from underwater to above sea level due to an earthquake.
Darwin extended his observations to the evolution of organisms.

23. Theory of Natural Selection

24. KEY CONCEPT Darwin proposed natural selection as a mechanism for evolution.

25. Several key insights led to Darwin’s idea for natural selection.
Darwin noticed a lot of variation in domesticated plants and animals.
Artificial selection is the process by which humans select traits through breeding.
neck feathers
crop
tail feathers

26. Natural selection is a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals.
Heritability is the ability of a trait to be passed down.
There is a struggle for survival due to overpopulation and limited resources.
Darwin proposed that adaptations arose over many generations.

27. Natural selection explains how evolution can occur.
There are four main principles to the theory of natural selection.
variation
overproduction
adaptation
descent with modification
Fitness is the measure of survival ability and ability to produce more offspring.
ADAPTATION
OVERPRODUCTION
VARIATION
DESCENT with MODIFICATION

28. Natural selection acts on existing variation.
Natural selection can act only on traits that already exist.
Structures take on new functions in addition to their original function.
wrist bone
five digits

29. Evidence for Evolution

30. KEY CONCEPT Evidence of common ancestry among species comes from many sources.

31. Evidence for evolution in Darwin’s time came from several sources.
Fossils provide evidence of evolution.
Fossils in older layers are more primitive than those in the upper layers.

32. The study of geography provides evidence of evolution.
island species most closely resemble nearest mainland species
populations can show variation from one island to another

33. Embryology provides evidence of evolution.
identical larvae, different adult body forms
similar embryos, diverse organisms
Larva
Adult barnacle
Adult crab

34. The study of anatomy provides evidence of evolution.
Homologous structures are similar in structure but different in function.
Homologous structures are evidence of a common ancestor.
Human hand
Bat wing
Mole foot

35. The study of anatomy provides evidence of evolution.
Analogous structures have a similar function.
Human hand
Bat wing
Mole foot
Fly wing
Analogous structures are not evidence of a common ancestor.

36. Structural patterns are clues to the history of a species.
Vestigial structures are remnants of organs or structures that had a function in an early ancestor.
Ostrich wings are examples of vestigial structures.

37. Evolutionary Biology Today

38. Fossils provide a record of evolution.
Paleontology is the study of fossils or extinct organisms.

39. Paleontology provides evidence to support evolution.

40. Molecular and genetic evidence support fossil and anatomical evidence.
Two closely-related organisms will have similar DNA sequences.

41. Pseudogenes are sequences providing evidence of evolution.
no longer function
carried along with functional DNA
can be clues to a common ancestor

42. Hox genes indicate a very distant common ancestor.
control the development of specific structures
found in many organisms
Protein comparisons, or molecular fingerprinting reveals similarities among cell types of different organisms.

43. Evolution unites all fields of biology.
Scientist from any fields contribute to the understanding of evolution.
The basic principles of evolution are used in many scientific fields.