Evolution Understanding the Diversity of Life – Part 1 1

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

History of Evolutionary Theory 3

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

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

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

Early Ideas about Earth’s Organisms James Hutton & Charles Lyell Stated that various geological forces constantly changed the planet very slowly Idea Known as Gradualism or Uniformitarianism 7

Early Ideas about Earth’s Organisms Hutton & Lyell, cont. Proposed that the Earth was millions of years instead of a few thousand years old 8

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

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

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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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

Charles Darwin the Naturalist 14

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

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 16

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 17

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The Struggle for Existence Darwin’s Observations and Conclusions 19

Darwin’s Observations Patterns of Diversity Unique adaptations in organisms Species not evenly distributed 20

21 Giant Ground Sloth

22 Glyptodon – Ancestor of Modern Armadill o

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 23

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. 24

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” 25

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” 26

Darwin’s Theory of Evolution Organisms Change Over Time 27

Evolution: Defined Evolution is the slow, gradual change in the alleles of a population over time 28

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 29

Darwin’s Theory of Evolution Descent with Modification: Organisms descended from common ancestors Organisms change with time, diverging from a common form 30

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 31.

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