Along his journey, Darwin kept notes on the variation in different species. His book, Origin of Species, outlined his findings & theories in 1859.

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2 CHARLES DARWIN Born February 12, 1809 At the age of 16 entered medical school in England and flunked out His dad sent him to Univ. of Cambridge in 1827 to study divinity 1831: Darwin left Cambridge and was asked to join an expedition

3 DARWIN S DISCOVERIES He leaves on the HMS Beagle for 5 years Collected fossils (evidence) Observed organisms on Galapagos Islands His passion & observation of geology led to his most notable discovery

4 GALAPAGOS ISLANDS

5 DARWIN S OBSERVATIONS Along his journey, Darwin kept notes on the variation in different species His book, Origin of Species, outlined his findings & theories in 1859.

6 RECALL: Biodiversity: variations among all organisms in the biosphere What scientific explanation accounts for diversity in life? A collection of scientific facts, observations, and hypotheses otherwise known as evolutionary theory

7 3 PATTERNS OF BIODIVERSITY THAT DARWIN NOTICED: Species vary globally Species vary locally Species vary over time

8 SPECIES VARY GLOBALLY Different but similar animals inhabit similar but separate habitats around the world i.e. grasslands Rhea: S. America Ostrich: Africa Emu: Australia

9 SPECIES VARY LOCALLY Different but related species occupy different habitats within a local area Isabela Island Tortoise Pinta Island Tortoise Hood Island Tortoise

10 SPECIES VARY OVER TIME Some fossils of extinct animals were similar to living species Fossils are evidence of variation over time armadillo glyptodon

11 OTHER DISCOVERIES AT THE TIME Geologists Hutton Lyell Naturalists Lamarck

12 JAMES HUTTON -Geological change shapes Earth Certain types of rocks are formed from molten lava Others are formed slowly as sediments build up Grand Canyon: rock layers formed millions of years ago, and washed away by the river Rocks push up, forming mountains Deep time: planet is so old that it is difficult for us to imagine

13 CHARLES LYELL Uniformitarianism: geological processes we see in action today are the same that shaped the earth millions of years ago Volcanoes released lava and gases Rivers dug channels and carved canyons Darwin found marine animal fossils in mountains thousands of feet above sea level -Earthquakes repeating many times could build mountains a few feet at a time

14 JEAN-BAPTISTE LAMARCK Theory of Heredity Three main principles Black-necked Stilt 1. Organisms constantly try to improve themselves (acquired characteristics) 2. Most used body structures developed and unused structures waste away ( use it or lose it ) 3. Once a structure modifies itself, is passed down (inherited) - Inheritance of acquired traits

15 EVALUATING LAMARCK Wrong: -Organisms do not have a drive to become more perfect -Evolution does not mean a species becomes better over time -Evolution does not progress in a predetermined direction What he got right: -Species are capable of change -Explain evolution using natural processes -Link between body structures of organisms and environment

16 THOMAS MALTHUS Human population growth Humans are being born faster than they are dying leads to overcrowding Forces working against population growth: War Famine Disease

17 DARWIN S THEORIES 1. Evolution did occur 2. Evolutionary change was gradual, requiring thousands to millions of years 3. Primary mechanism for evolution was a process called natural selection 4. The millions of species alive today arose from a single original life form through a process called speciation.

18 NATURAL SELECTION process by which organisms with favorable traits survive longer and reproduce more survival of the fittest The one that is best suited for the environment (not necessarily the strongest) survives Opposite= artificial selection Nature provides variation and humans select those that they find useful What does this seem similar to?

19 DARWIN = FATHER OF EVOLUTION Darwin s theory attempted to explain how various species evolved Russell Wallace (another British naturalist) reached a similar conclusion & shared his ideas with Darwin He allowed Darwin to take credit for their ideas

20 FORCES BEHIND NATURAL SELECTION 4 main factors that drive natural selection 1. Overpopulation 2. Variation 3. Competition 4. Survival of the fittest

21 OVERPOPULATION A species has more offspring than can survive to reproductive maturity

22 VARIATION The individuals in a population have different traits Structural Behavioral Physiological

23 COMPETITION Individuals compete against each other for limited resources

24 SURVIVAL OF THE FITTEST organisms that survive due to their fitness for the environment reproduce and pass the favorable traits (adaptations) to their offspring

25 ADAPTATIONS Inherited traits that increase a population s chance of survival differences in inherited traits present in a given population are called variation variation is due to the events of meiosis (crossing over & independent assortment) and mutations that produce favorable characteristics

26 Fitness : how well an organism can survive and reproduce in its environment. High fitness: adaptations that are well-suited to their environment can survive and reproduce Low fitness: characteristics that are not well-suited for the environment cause organisms to either die without reproducing or leave few offspring Survival : reproducing and passing adaptations on to the next generation.

27 MISCONCEPTIONS Natural selection does not make organisms better Adaptations don t have to be perfect just good enough to enable an organism to pass its genes to the next generation. Natural selection does not move in a fixed direction There is no one, perfect way of doing something. i.e. tree pollination: oak treesà wind apple tree flowersà insects

28 DESCENT WITH MODIFICATION Well-adapted organisms survive and reproduce Leave descendents Common ancestors (descent with modification) Fossil record Evolutionary tree