Chapter 15 Darwin s Theory of Evolution. Essential Question: What evidence did Darwin use to develop his theory of evolution?

Transcription

1 Chapter 15 Darwin s Theory of Evolution Essential Question: What evidence did Darwin use to develop his theory of evolution?

2 15-1 The Puzzle of Life s Diversity How did life change from a prokaryote to all of this in 4.6 billion years?

3 What is a theory? How does this relate to evolution? Theory is A well supported hypothesis. There is A LOT of data and observation that supports a theory. Evolution is a theory It is used to describe the processes by which modern organisms have descended through time from ancient organisms.

4 Charles Darwin born in 1809, the same birthday as Abraham Lincoln In 1832, after graduating from college, sailed around the world aboard the HMS Beagle working as an unpaid naturalist this voyage changed his thinking about natural history and changed the course of science

5 Voyage of HMS Beagle 1832 (technically Dec. 27, 1831) - HMS Beagle set sail to travel the world Aboard was Charles Darwin There to study plants and animals in South America, Africa, and Australia.

6 Darwin s Observations 1. Patterns of Diversity 2. Living Organisms and Fossils 3. The Galapagos Islands

7 These ladybugs are members of the same species yet their coloration varies. Why is this important? 1. Patterns of Diversity

8 Diversity on Earth Many different kinds of organisms Each is suited for its environment These traits that make them well suited are called adaptions

9 Variation can lead to diversity Cheetahs vary in speed. Can lead to starvation

10 Darwin s Influences? Observations of Adaptations collected samples and observed species in their natural environment. noticed that organisms tended to be well suited ( adapted) to their environment.

11 2. Living Organisms and Fossils

12 Living Organisms and Fossils Darwin wondered why the animal species he saw in the fossil record had disappeared? What processes were leading to the loss and rise of species? Why did they look similar, but exhibit changes through the fossil record?

13 3. The Galapagos Islands

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16 What are adaptations? How does variation lead to adaptation? Inherited traits that increase a population s chances of survival and reproduction are called ADAPTATIONS

17 Type of Adaptations Observed in Animals Physical camouflage, mimicry Defense: spines, quills, armor Chemical Smells, poisons, venom, sap, sprays Behavioral Innate and learned Migration, hibernation (torpor) Courtship rituals

18 Biodiversity: Global Village The variety and abundance of different species is called BIODIVERSITY. Earth is estimated to have 5 million to 30 million different living species. Estimates suggest that 99% of all organisms that ever lived are now extinct.

19 Scientists over time began to ask questions Why is there such incredible Biodiversity? Why have so many species come and gone? One man s quest for an answer led to perhaps the most revolutionary theory in the history of science...

20 15-2 Ideas That Shaped Darwin s Thinking Essential Question: How did past scientists thinking help with Darwin s idea of Evolution?

21 How did Darwin develop his theory of Evolution? What were his 3 major influences?

22 Influence 1: An Ancient Changing Earth James Hutton Proposed Earth is shaped by geological forces These forces take millions of years Therefore Earth is millions of years old, not thousands Charles Lyell Published Principles of Geology which Darwin read while aboard the HMS Beagle Explained the mechanisms for geological change Insisted scientists must make modern observations to explain past events

23 How did this influence Darwin? Geology the geology work of Charles Lyell and James Hutton geological evidence suggested Earth was very old reasoned that if the Earth changed over time, these changes would influence plant and animal life. fossil evidence seems to support this.

24 Influence 2: Lamarkian Evolution Jean Baptiste Lamarck Developed one of the first evolutionary hypotheses in 1809 Did not believe all creatures shared a common ancestor

25 Lamarck s Evolution Hypothesis 3 Parts Tendency towards Perfection Use and Disuse Inheritance of Acquired Traits

26 Part 1. Tendency Towards Perfection Organisms strive to improve themselves throughout their lifetime

27 Part 2. Use and Disuse Used body structures remain and develop: and unused body structures waste away

28 Part 3. Inheritance of acquired traits Characteristics acquired during the lifetime of an organism could be passed to offspring. tommee.glogster.com

29 Darwin Didn t Buy It He questioned prior ideas and sought a better explanation

30 Influence 3: Thomas Malthus Economist Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone

31 Darwin Influences? Population Control All populations eventually exceed the supply of resources (living space and food) Health/Infant-dying-starvation.jpg Populations would eventually be limited by disasters such as starvation, drought, war, etc. Remember what you learned in Chapter 5!

32 Application to Darwin Darwin noticed species will over produce offspring. Most die off. What causes the death of so many individuals?

33 15-3 Darwin Presents His Case Essential Question: What evidence of evolution did Darwin present? How does natural selection lead to evolution?

34 Charles Darwin s Theory of Evolution published in 1859 On the Origin of Species by Means of Natural Selection Portrait of Charles Darwin

35 The Origin of Species When Darwin returned from his voyage, he hesitated to publish work. Finally published his book in 1859 when learning colleague was working on the same topic.

36 Sources of Heritable Variation 4 Sources of Variation 1. crossing over 2. independent assortment 3. recombining of egg and sperm 4. random mutations

37 Fitness Species that are more adapted to their environment are have better fitness Which animal fitness is higher to live in the desert?

38 Natural Selection The survival of the fittest The process where organisms that are better suited for their environment tend to survive and produce more offspring

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40 Natural Selection: 4 Steps 1. genetic variation must be present within a population 2. some variations must be more favorable and allow organisms to survive and reproduce

41 Natural Selection: 4 steps 3. survival must be differential 4. favorable traits must be inherited by offspring

42 So, what was Darwin s Big Idea?

43 Evolution as a result of Natural Selection the theory that species descended from more ancient forms of life through structural and physiological modifications as a result of natural selection of traits What evidence exists in support of this idea?

44 Types of Modern and Historical Evidence for the Theory of Evolution: 1. fossil record 2. chemical similarities 3. structural similarities 4. geographic distribution of species

45 Evidence for Evolution: Fossil Formed by ancient plants or animals Older fossils are found under newer fossils Fossils

46 The Fossil Record Paleontologists study fossils for clues. / FOSSILS are the preserved remains or imprints of ancient organisms.

47 Evidence of change and extinction? Remains of plants and animals found in sedimentary rocks Some extinct species had traits that were transitional between major groups of organisms Confirms that species are not fixed.

48 Evidence of Habitat Change most common fossils found in sedimentary rocks are from the hard parts of organisms, including shells, bones, teeth, and woody stems.

49 Not just bones Fossils are not always the body parts of an organism. A mold is a type of fossil in which an impression of the shape or track of an organism has survived

50 Amber Impressions Freezing

51 The Fossil Record Fossils can be dated using: radioactive isotopes relative dating based on their position in the sedimentary rock Video Shorts you can watch at home!

52 Structural Similarities Homologous Structures Structures that are embryologically similar, are called homologous structures. This suggests that these animals evolved from a common ancestor.

53 Structural Similarities Structures that are similar in function but different in structural origin are called analogous structures They are not inherited from a common ancestor.

54 Examples of analogous structures include: Insect wings and bird/bat wings both are used for flying, but are not from the same genetic origin

55 Similar in Appearance and Function Homologous or Analogous?

56 Similar in Appearance BUT NO COMMON ANCESTOR!

57 Structural Similarities The presence of structures that have a minimal purpose or no purpose at all are called Vestigial Structures

58 Evidence for Evolution: Embryos The early stages, or embryos, of many animals with backbones are very similar

59 Comparative Embryology Similarities in embryological development suggests a common ancestor and similar genetics.

60 Evidence for Evolution: Geographic Distribution Animals found in the same geographic area tend to have multiple similarities Example: Marsupials in Australia

61 Chemical Similarities The genetic code is the same for ALL organisms. similar DNA sequences in all organisms. Greater similarities in DNA sequences implies greater evolutionary relatedness.

62 Evidence for Evolution: All life on Earth shares at least SOME of the same DNA The more DNA you share, the more closely related on the evolutionary tree. Molecular Biology