1. Principles of evolution

2. evolution
The process of biological change by which descendants come to differ from their ancestors
Early scientists proposed ideas about evolution

3. Carolus linnaeus 1700s Swedish botanist
Developed a classification system for all organisms known at the time based on their similarities and evolutionary relationships
Binomial Nomenclature

4. Georges louis leclerc de buffon
1700s French Naturalist
Proposed that species shared common ancestors instead of arising separately
Challenged the idea that Earth was only 6,000 years old
Ideas were similar to geologist Charles Lyell’s

5. Erasmus darwin Darwin’s grandfather, born in 1731
Respected English doctor and poet
Proposed that:
all living things were descended from a common ancestor
more complex forms of life arose from less-complex life forms

6. Jean-baptiste lamarck
French naturalist
Proposed that all organisms evolved toward perfection and complexity

7. Jean Baptiste Lamarck
Believed that over a lifetime of an individual physical features:
Increase in size the more they are used
Decrease in size the less they are used
These changes are then passed onto offspring
“Inheritance of Acquired Characteristics”

8. Lamarck’s Theory was…
WRONG!

9. Charles Darwin ( )
1859: “On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”
Has convincing evidence that species evolve
Describes a reasonable explanation of how evolution occurs

10. Charles Darwin Destined to become a doctor or a minister
Liked the outdoors and collecting samples
Age 22: invited to be a naturalist on a voyage of the HMS Beagle
History would never be the same

11. Darwin’s Voyage Charles Lyell’s book: “Principles of Geology”
Book suggested the surface of the Earth changed slowly over many years
Darwin thought: couldn’t species have changed too?

12. Thomas Malthus English economist
1798 essay claimed human populations are able to increase faster than the food demand
They do not grow unchecked because death caused by disease, war and famine slows population growth
Darwin thought: Doesn’t this happen with all living species?

13. Theories of geologic change set the stage for darwin’s theory
Fossil: trace of an organism from the past
Catastrophism: theory that states that natural disasters such as floods and volcanic eruptions shaped Earth’s landforms and caused extinction of some species
Gradualism: principle that states that the changes in landforms result from slow changes over a long period of time
Uniformitarianism: theory that states that the geological processes that shape Earth are uniform through time

14. Theories of geologic change set the stage for darwin’s theory

15. The Fossil Record
Fossils of animals show a pattern of development from early ancestors to modern descendants
Offer the most direct evidence that evolution takes place

16. The Fossil Record
Darwin predicted the intermediate forms between the great groups of organisms that would be found
Darwin’s theory is almost universally accepted by scientists as the best available explanation for biological diversity on Earth
Fossil intermediaries have been found between:
Fishes and amphibians
Reptiles and birds
Reptiles and mammals
                                      A model of Tiktaalik roseae, which fills in the evolutionary gap between fish and land animals, is depicted in what scientists believe to be the animal's environment about 375 million years ago.

17. The Fossil Record Most scientists agree:
Earth is about 4.5 billion years old
Organisms have inhabited Earth for most of its history
All organisms living today share common ancestry with earlier, simpler life-forms
The fossil record is not complete
The record of evolution of life is not complete

18. Darwin’s Voyage
Darwin saw things in his travels that could only be explained by gradual change
Visited the Galapagos Islands, 1000 km off the coast of Ecuador

19. Darwin’s Voyage “Descent With Modification”-Evolution
Noticed many of the plants and animals of the Galapagos resembled those of the nearby coast of S. America
Suggested the species migrated from S. America and changed after they arrived

20. Darwin’s observations
Darwin observed differences among island species
Variation: differences in physical traits of an individual from the group to which it belongs
Adaptation: inherited trait that is selected for over time because it allows organisms to better survive in their environment

21. Darwin’s Finches
9 distinct species of finches in the Galapagos Islands, all very similar to each other except for their bills
2 ground finches: large bills to feed on seeds that they crush with their beaks
2 with narrower bills eat insects
1 finch eats fruit
1 picks insects out of cactuses
1 drinks the blood of sea birds

22. Darwin’s Finches
Darwin suggested that the nine species evolved from a common ancestral species
During a year of rain, food is plentiful for all the finches

23. Darwin’s Finches Dry years Wet years
Longer, more massive beaks
Wet years
Smaller beaks returned
The number of birds with different beak shapes are changed by natural selection in response to the available food supply, as Darwin suggested

24. Darwin observed fossil and geologic evidence supporting an ancient earth

25. Publication of Darwin’s Work
1844 Darwin wrote down his ideas
Due to public criticism of Lamarck’s hypotheses, Darwin did not publish his findings
1858 Alfred Russel Wallace wrote an essay that summarized exactly what Darwin had believed for years!
1859 Darwin quickly published his book

26. Darwin’s Theory
Inherited variation exists within the genes of every population or species
The result of random mutation and translation errors

27. Darwin’s Theory
2. In a particular environment, some individuals of a population or species are better suited to survive
A result of variation
Have more offspring

28. Darwin’s Theory
3. Over time, the traits that make certain individuals of a population able to survive and reproduce tend to spread in that population

29. Darwin’s Theory
4. There is overwhelming evidence from fossils and many other sources that living species evolved from organisms that are extinct

30. Several key insights led to Darwin's idea for natural selection

31. Artificial selection
Process by which humans modify a species by breeding it for certain traits

32. Natural Selection
Individuals that have physical or behavioral traits that better suit their environment
More likely to survive
More likely to reproduce successfully
Peppered Moth Example

33. Natural Selection
The number of individuals that carry favorable characteristics that are inherited will increase in the population
The nature of the population will change…
Evolution

34. Population
All the individuals of a species that live in a specific geographical area and that can interbreed

35. Natural selection explains how evolution can occur
Variation
Overproduction
Adaptation
Descent with modification

36. principles of natural selection

37. fitness
Measure of an organism’s ability to survive and produce offspring relative to other members of a population s

38. Natural selection acts on existing variation
Acts on phenotypes, not genotypes

39. Evidence of evolution in Darwin’s time came from several sources
Fossils
Geography
Embryology

40. Homologous Structures
Anatomical structures that share a common ancestry

41. Homologous Structures
Most scientists believe that the evolutionary history of organisms is also seen in the development of embryos
At some point, all vertebrate embryos have a tail, buds that become limbs, and pharyngeal pouches
The tail remains in most adult vertebrates (humans lose it during fetal development)
Only fish and immature amphibians retain pharyngeal pouches (in humans it develops into structures in the throat)

43. Analogous structures
Body part that is similar in function as a body part of another organism but is structurally different

44. Structural patterns are clues to the history of a species
Vestigial structures: remnants of an organ or structure that functioned in an earlier ancestor
Reduced in size and function

45. Evolutionary biology today

46. Molecular and genetic evidence support fossil and anatomical evidence
DNA sequence analysis
Pseudogenes
Homeobox genes
Protein comparisons

47. Biological Molecules
As physical changes occur in the fossil record, genes that determine the species characteristics should have changed as well
Proteins and DNA sequences can be used to determine the relatedness of species

48. Evolution unites all fields of biology