1 Ch.14 Origin of Life

2 Fossil Record Earth is 4.6 Billion Years Old Fossils In Different Layers of Rock Showed Evidence life began 3.5 BYA

3 Aristotle (384 –322 BC) Proposed spontaneous generation=abiogenesis living things can arise from nonliving matter

4 Examples of Spontaneous Generation

5 Example #1 muddy soil gave rise to the frogs

6 Example #2 mice came from the moldy grain.

7 Example #3 sewage and garbage turned into the rats sewage and garbage turned into the rats.

8 Example #4 rotting meat gave rise to maggots

9 Disproving Spontaneous Generation

10 Francesco Redi (1668) 1668, Francesco Redi, disproved spontaneous generation

11 Redi’s ( ) Experiments Evidence against spontaneous generation:

12 Disproving Spontaneous Generation of Microbes

13 Lazzaro Spallanzani’s (1765) Boiled broth and melted top shut. The soups remained clear. Later broke seals & soups became cloudy

14 Conclusion Critics said sealed vials killed “vital force”

15 Pasteur's Experiment - Step 1 S-shaped Flask Filled with broth special shape to trap dust

16 Pasteur's Experimental Results Proved microbes only come from other microbes (life from life) - biogenesis

17 Ch. 15 Evolution Diversity of Life

18 Definition Evolution is the slow, gradual change in a population over time

19 Lamarck’s Theory of Evolution Jean-Baptiste Lamarck, 1809 “Changes Are acquired in an organism’s lifetime” acquired changes were passed to offspring

20 Lamarck’s Theory of Evolution Idea called Law of Use and Disuse If a body part were used, it got stronger If body part NOT used, its lost

21 Lamarck’s Theory of Evolution Clipped ears be passed to offspring!

22 Charles Darwin the Naturalist

23 Voyage of the Beagle Charles Darwin Born Feb. 12, 1809 Joined Crew of HMS Beagle, 1831 Naturalist 5 Year Voyage around world

24 Darwin’s Voyage of Discovery

25 Darwin Left England in 1831 Darwin returned 5 years later in 1836

26 The Galapagos Islands Animals On Islands Unique Tortoises Iguanas Finches

27 The Galapagos Islands

28 Darwin’s Conclusion Scarcity of resources leads to struggle for existence Only a fraction of offspring survive =Survival of the Fittest Called Natural Selection

29 Publication of “On The Origin of Species” But He Did Not Publish For 25 Years – Why?

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35 A Common Misconception…

36 selective breeding Artificial Selection = “selective breeding” Examples: Dogs

37 Artificial Selection Examples: Dogs

38 Artificial Selection Crops, Examples: Crops, Decorative Plants

39 Theory of Evolution Today Supporting Evidence

40 Evidence for Evolution – The Fossil Record

41 How do scientists figure out how old something is? Relative dating —looking at where the rock is located.

42 How do scientists figure out how old something is? Radioactive dating — measuring radioactive decay.

43 Similarities in DNA Sequence

44 Evolution of pesticide resistance in response to selection

Upsetting Genetic Equilibrium  Natural selection is not the only way that allele frequencies can change from one generation to the next.  Genetic Drift – a random loss of alleles.  Mutation – a new mutation can add alleles.  Nonrandom mating – inbreeding increases the number of homozygous traits.  Migration – shuffles alleles between populations; can prevent speciation.

Genetic Drift  smaller the sample, the greater the chance of deviation  These random deviations are called genetic drift.  more likely in small populations.

Genetic Drift  allele gets lost is due to random chance.  Over time, drift tends to reduce genetic variation through random loss of alleles.  C R C R = red  C R C W = pink  C W C W = white Frequency C R = 0.5 Frequency C W = 0.5 Frequency C R = 0.7 Frequency C W = 0.3 Frequency C R = 1.0 Frequency C W = 0

The Bottleneck Effect  Sometimes a catastrophic event can severely reduce the size of a population.  The random assortment of survivors may have different allele frequencies.  This is a type of genetic drift called the bottleneck effect.

The Bottleneck Effect  The actions of people sometimes cause bottlenecks in other species.  N. California elephant seal population reduced to individuals in the 1890s.  Current population > 30,000.  Variation drastically reduced – 24 genes with 1 allele.

The Founder Effect  Founder effect – Another type of genetic drift occurs when a small group of individuals becomes separated from the population and form a new population. The allele frequencies in their gene pool may be different than the original population.

51 Camouflage & Mimicry

52 Homologous Structures = Same Structure, Different Function

53 Ex. Appendix In Man Legs On Skinks Vestigial Organs = structure with no function

54 Vestigial Structures —a body part that is reduced in size and does not seem to have a function. Examples: appendix, wisdom teeth and moving ears.

55 Embryology —study of the development of embryos Examples Examples: gills and tailbones in humans

56 Chicken Turtle Rat Embryonic Structures