Theories on the Origin of Life

1. Theories on the Origin of Life • Spontaneous generation is the theory that life can come from non-living matter. (Frogs come from mud, flies come from garbage, etc.)

2. Disproved by Redi (1600) – covered materials don’t produce flies.

3. Maggots are – larvae stage of a fly

4. Spontaneous generation of microbes was disproved byLouis Pasteur (1860)- theory of biogenesis - life come from life

5. Heterotroph Hypothesis– life arose from a combination of inorganic chemicals methane (CH4), ammonia (NH3) + water (H2O) that existed in the ancient oceans of earth. • Miller and Urey experiment (1953) formed amino acids • Fox – amino acids will form proteins at high temperatures • Proto- cells formed

6. Warbler finch Cactus eater Tree finches Ground finches Insect eaters Seed eaters Bud eater Darwin & Evolution by Natural Selection

7. Charles Darwin • Proposed a way how evolution works • How did creatures change over time? • by natural selection • Collected a lot of evidence to support his ideas • 1809-1882 • British naturalist

8. Voyage of the HMS Beagle • Invited to travel around the world • 1831-1836 (22 years old!) • makes many observations of nature • main mission of the Beagle was to chart South American coastline Robert Fitzroy

9. Voyage of the HMS Beagle • Stopped in Galapagos Islands • 500 miles off coast of Ecuador

10. Galapagos Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland. 800 km west of Ecuador

11. Darwin found…many unique species Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands?

12. present day Armadillos ancient Armadillo Darwin found…clues in the fossils Darwin found: Evidence that creatures have changed over time Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent?

13. present day Sloth (extinct) Giant ground sloth Darwin found… more fossils Darwin found: Evidence that creatures have changed over time Darwin asked: Why should extinct sloths & modern sloths be found on the same continent?

14. Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like?

15. Finch? Sparrow? Warbler? Woodpecker? Darwin found… birds Darwin found: Many different birds on the Galapagos Islands. He thought he found very different kinds… Finch? Sparrow? Warbler? Woodpecker?

16. Finch? Sparrow? Warbler? Woodpecker? But Darwin found… a lot of finches Darwin was amazed to find out: All 14 species of birds were finches… But there is only one species of finch on the mainland! Large ground finch Small ground finch Finch? Sparrow? Darwin asked: If the Galapagos finches came from the mainland, why are they so different now? Warbler finch Tree finch Warbler? Woodpecker?

17. Finch? Sparrow? Warbler? Woodpecker? The finches cinched it! • different beaks are inherited variations • serve as adaptationsthat help birds compete for food • these birds survive & reproduce • pass on the genes for those more fit beaks • over time nature selected for different species with different beaks Darwin found: The differences between species of finches were associated with the different food they ate. Darwin said: Ahaaaa! A flock of South American finches were stranded on the Galapagos… Large ground finch Big seed eater Small ground finch Small seed eater Warbler finch Insect eater Tree finch Leaf & bud eater

18. Relationship between species (beaks) & food

19. Darwin’s finches • Darwin’s conclusions • variations in beaks • differences in beaks in the original flock • adaptations to foods available on islands • natural selection for most fit • over many generations, the finches were selected for specific beaks & behaviors • offspring inherit successful traits • accumulation of winning traits:both beaks & behaviors • separate into different species

20. Warbler finch Cactus finch Woodpecker finch Sharp-beaked finch Small insectivorous tree finch Small ground finch Warbler finch Large insectivorous tree finch Cactus eater Medium ground finch Tree finches Ground finches Insect eaters Seed eaters Large ground finch Vegetarian tree finch Bud eater From 1 species to 14 species… natural selection for best survival & reproduction variation

21. Earlier ideas on Evolution • LaMarck • evolution by acquired traits • creatures developed traits during their lifetime • give those traits to their offspring • example • in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring • not accepted as valid

22. Darwin’s view of Evolution • Darwin • giraffes that alreadyhave long necks survive better • leave more offspring who inherit their long necks • variation • selection & survival • reproduction & inheritance of more fit traits 

23. Darwin’s Theory of Natural Selection • #1 Overproduction • Organisms tend to have many more than two offspring so at least some will survive (yet populations usually do not grow rapidly in the wild)

24. #2 Competition - Therefore they must compete for resources (food, space, mates)

25. Natural Selection • #3 Variation - variation within the population. • #4 Adaptation - Therefore some of them must be better adapted to their environment

26. Sources of Variation • A. Mutation • A mutation is a change in the DNA of an organism due to external or internal factors. (toxins, radiation, random,etc.) • Most mutations are NOTbeneficial to the organism. • Some may become beneficial if the environment changes, provided they do not harm the individual. (ex. Giraffe’s neck)

27. #5. Natural Selection- the ability of organisms that are best adapted to survive and reproduce . Those that are less adapted will not survive.

28. Speciation • Eventually, over generations and time, new species will evolve from older forms by natural selection of better adapted forms.

30. Divergent Evolution

31. Evidence for EvolutionAll of the fields of Life Science show evidence of evolution. • A. The Fossil Record • Fossil: the remains or evidence of past life recorded in rock. • (molds, impressions, bones, shells, teeth, preserved in ice, etc.) • 1. Fossils are found most often sedimentary rock. • 2. Relative age can be determined by the fossils position in the layers. The oldest fossils are found below the younger ones.

32. 3. Absolute dating uses the principal of radioactive dating • The half-life of known radioactive compounds never changes. • (ex. Carbon 14 found in bones and shells can determine their actual age in years). • Ex. Fossil remains clearly show the gradual evolution of the modern horse.

33. B. Comparison of Similar Anatomy or Structures 1. Homologousstructures - those that appear to have come from a common ancestor. These indicate that species are related. • Ex. Bats wing, human arm and whale flipper bones.

34. 2._ananlogous__________ structures that are used for the same function but are not similar. These indicate species are not related. Same function different structure

35. vestigial _______- a structure, or organ, that appears to have lost all, or most, of its functions

36. Comparative Anatomy

37. Comparative Embryology • Comparative Embryology – examination of differences and similarities in embryodevelopment (beforebirth). • ex. Comparison of bird, fish and early human embryos

38. F. • BiochemicalComparisons • Recent developments (Human Genome Project) have allowed for the comparison of DNA from different species and groups within species. This new evidence is the strongest yet that consistently supports accepted evolutionarytheory. • DNA - our DNA and that of a Chimpanzee is more than 99% identical. Gorillas and Baboons have somewhat less (95-97%) and mice have 80% identical DNA. • Ex. Cytochrome C, a respiratory enzyme common to all animals is slightly different in different species. Humans differ from monkeys by oneamino acid in their cyt C. We differ from pigs by 10 amino acids. Chicken cyt C has 13 different amino acids and fish differ by 21. This clearly shows the accepted evolutionary relationship between vertebrates.

39. Asking Questionsis a good adaptation!