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Evolution Understanding the Diversity of Life – Part 1 1.

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Presentation on theme: "Evolution Understanding the Diversity of Life – Part 1 1."— Presentation transcript:

1 Evolution Understanding the Diversity of Life – Part 1 1

2 2 “ Nothing in biology makes sense EXCEPT in the light of evolution.” Theodosius Dobzhansky Evolution Charles Darwin in later years

3 History of Evolutionary Theory 3

4 Early Ideas about Earth’s Organisms Aristotle believed species were fixed creations arranged by their complexity 4

5 Early Ideas about Earth’s Organisms Carolus Linnaeus 1 st to group similar organisms and assign them Latin names Two word name (Genus species) Known as Binomial nomenclature 5

6 Early Ideas about Earth’s Organisms Georges Cuvier Some species’ fossil records disappeared in more recent layers Stated that species disappear due to a catastrophic event of the earth’s crust 6

7 Early Ideas about Earth’s Organisms James Hutton & Charles Lyell Stated that various geological forces constantly changed the planet Changes in Earth’s crust were due to slow continuous processes Idea Known as Gradualism or Uniformitarianism 7

8 Early Ideas about Earth’s Organisms Hutton & Lyell, cont. Geological processes moved at uniform rates; building & wearing down Earth’s crust Proposed that the Earth was millions of years instead of a few thousand years old 8

9 Early Ideas about Earth’s Organisms Reverend Thomas Malthus Studied macroeconomics Stated that populations could not grow indefinitely This growth would be stopped by: 1.Disease 2.Famine 3.War 9

10 Lamarck’s Theory of Evolution Jean-Baptiste Lamarck One of first scientists to understand that organisms change over time Put forth an idea called Inheritance of Acquired Characteristics through Law of Use and Disuse 10

11 Lamarck’s Theory of Evolution Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime Examples: blacksmiths & their sons (muscular arms) giraffe’s necks longer (from stretching) These traits could then be passed on to their offspring Over time this would lead to new species 11

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13 Lamarck’s Mistakes Inheritance Of Acquired Traits Traits Acquired During Ones Lifetime Would Be Passed To Offspring If true, clipped ears would pass to offspring! 13

14 Lamarck’s Mistakes Lamarck did NOT know how traits were inherited (traits are passed through genes) Genes are NOT changed by activities in the life of an organism Change occurs through mutations of genes These mutations occur before the organism is born 14

15 Charles Darwin the Naturalist 15

16 Charles Darwin Born Feb. 12, 1809 A naturalist Collector/identifier of plant and animal specimens Formed his ideas about evolution sailing on the HMS Beagle for the Galapagos Island in

17 The Galapagos Islands Small group of islands 1000 km west of Ecuador Very different climates and geography on each island Animals on each of the islands similar but unique 17

18 The Galapagos Islands Islands all formed by action of volcanoes Island species varied from mainland species & from island-to-island species Each island had long or short neck tortoises 18

19 The Galapagos Islands Finches on the islands resembled a mainland finch Different types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had beaks adapted to their type of food gathering 19

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21 The Struggle for Existence Darwin’s Observations and Conclusions 21

22 Darwin’s Observations Patterns of Diversity Unique adaptations in organisms Species not evenly distributed Examples: Australia: kangaroos South America: llamas Africa: elephants 22

23 Darwin’s Observations Darwin collected living organisms and fossils on his voyage Took these back to England to study 23 This species NO longer existed. What had happened to them?

24 24 Giant Ground Sloth

25 25 Glyptodon – Ancestor of Modern Armadill o

26 Darwin’s Observations Unlimited resources will allow organisms increase exponentially, generation to generation In nature, populations tend to remain stable in size Environmental resources are what limits population size 26

27 Darwin’s Observations Individuals of a population vary in their characteristics with no two individuals being exactly alike. Much of this variation between individuals is inheritable. 27

28 Darwin’s Conclusions Production of more individuals than can be supported by the environment leads to a struggle for existence Only a fraction of offspring survive each generation He called this “Survival of the Fittest” 28

29 Darwin’s Conclusions Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals He called this “Natural Selection” 29

30 Ideas that Shaped Darwin’s Thinking 30

31 Ideas that Shaped Darwin’s Thinking Hutton & Lyell Expanded Earth’s age from 6000 to billions of years Explained geological processes that shaped the earth Helped Darwin understand the presence of sea shells in the Andes mountains at 12,000+ feet 31

32 Ideas that Shaped Darwin’s Thinking Malthus’ Influence Babies are born faster than people die Total population size limited by resources such as the food supply High birth rates & limited resources would force life & death competition Each Species Struggles For: Food Living Space Mates 32

33 Darwin’s Theory of Evolution Organisms Change Over Time 33

34 Evolution: Defined Evolution is the slow, gradual change in the alleles of a population over time 34

35 Darwin’s Theory of Evolution The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (Natural Selection) This creates new species 35

36 Darwin’s Theory of Evolution Descent with Modification: Organisms descended from common ancestors Organisms change with time, diverging from a common form 36

37 Darwin’s Theory of Evolution Natural Selection: Driving force for evolution During the struggle for resources, strongest survive & reproduce Idea that at least some of the beneficial differences between individuals are inheritable 37.

38 Publication of: “On The Origin of Species” Upon his return To England, Darwin spent 25 years developing his observations into the Theory of Evolution He hesitated to publish because: 1. He knew that his theory would be extremely controversial and would be attacked 2. His theory challenged established religious & scientific beliefs; particularly about the Creation of Man 38

39 Alfred Russel Wallace Fellow naturalist Sent an essay of his work to Darwin to review Had independently come to the conclusion that species changed over time because of their struggle for existence When Darwin read Wallace’s essay, he knew he had to publish his findings 39 “O’ no you didn’t! This was my Idea!” - Darwin

40 Publication of: “On The Origin of Species” Darwin presented Wallace’s essay & some of his work at a conference in July of 1858 Then he started work on his book “Origin of Species” which was published in 1859 Spent the rest of his life refining his ideas about evolution Darwin died in 1882, the father of 10 children; 7 survived to adulthood 40

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