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Where did they originate ? 1 Theory of Spontaneous Generation 1. 2. Living organisms arose “spontaneously” Believed to explain “animalcules” 2 Aristotle (384 –322 BC) 1. Proposed theory of spontaneous generation 2. Also called abiogenesis 3. lasted 2000 years 3 4 Examples of Spontaneous Generation 5 Example #1 Observation: Every spring, Nile River flooded areas of Egypt, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times 6 Example #1 Conclusion: perfectly obvious that muddy soil gave rise to frogs 7 Example #2 Observation: farmers stored grain in barns with thatched roofs (like Shakespeare’s house). leaking. leads to spoiled or moldy grain, and of course there were lots of mice around. 8 Example #2 Conclusion: It was obvious to them that the mice came from the moldy grain. 9 Example #3 Observation: for centuries Sewage flowed down the streets, and left over food was thrown out into the streets. Many cities had major rat problems and a disease called Bubonic plague. 10 Example #3 Conclusion: sewage and garbage turned into the rats. 11 Example #4 Observation: no refrigerators meant battling flies around meat. Typically, carcasses were “hung by their heels,” customers selected which chunk the butcher would carve off for them. 12 Example #4 Conclusion: rotting meat was the source of the flies. 13 Abiogenesis Recipes Recipe for bees: Kill a young bull, and bury it in an upright position so that its horns protrude from the ground. After a month, a swarm of bees will fly out of the corpse. 14 Abiogenesis Recipes Recipe for mice: Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat. In 21 days, mice will appear. 15 Disproving Spontaneous Generation 16 C. Francesco Redi (1668) 1. hypothesis was “rotten meat does not turn into flies” 17 Redi’s Findings 2. Evidence against SG: 1. Unsealed – maggots on meat 2. Sealed – no maggots 3. Gauze –maggots on gauze only 18 Results of Redi’s Experiments results only accepted for larger organisms 19 Disproving Spontaneous Generation of Microbes 20 D. John Needham (1745) 1. Showed microorganisms flourished in soups exposed to air 2. Claimed a “life force” could cause spontaneous generation 21 Needham’s Results 3. bacteria were already present didn’t boil long enough 22 E. Lazzaro Spallanzani’s (1765) 1. Boiled soups for an hour and sealed containers by melting. 2. soups remained clear. 3. Later, broke seals & soups became cloudy 23 Spallanzani’s Results 24 Conclusion 4. Critics said sealed vials did not allow “life force” 25 The Theory Finally Changes 26 F. Louis Pasteur (1822- 1895) 1. Performed experiments to disprove Theory of SG. 27 a. Pasteur's Experiment - Step 1 S-shaped Flask shape intended to trap any dust containing bacteria 28 b. Pasteur's Experiment Step 2 Flasks boiled Microbes Killed 29 c. Pasteur's Experiment - Step 3 Flask left at various locations Did not turn cloudy 30 Pasteur's Experimental Results 31 The Theory of Biogenesis Proved biogenesis 32 Figure 1.3 Evolution Diversity of Life 33 Evolution “Nothing in biology makes sense EXCEPT in the light of evolution.” Theodosius Dobzhansky 34 Charles Darwin in later years History of Evolutionary Thought 35 Early Ideas On Earth’s Organisms Aristotle believed species were fixed creations arranged by their complexity Idea lasted 2000 years 36 Early Ideas On Earth’s Organisms Linnaeus – 1st to group similar organisms and assign them Latin names Two word name (Genus species) Known as Binomial nomenclature 37 Evolutionary Timeline 38 Lamarck’s Theory of Evolution Jean-Baptiste Lamarck, 1809 Change Occurs Over Time Changes Are acquired in an organism’s lifetime acquired changes were passed to offspring 39 Lamarck’s Theory of Evolution Idea called Law of Use and Disuse If a body part were used, it got stronger 40 Lamarck’s Theory of Evolution Inheritance of Acquired Characteristics Traits Could Then Be Passed On To Their Offspring Over Time This Led To New Species 41 Lamarck’s Theory of Evolution Use & Disuse - Could Change The Size Or Shape Giraffe’s Necks Longer from stretching) 42 43 Lamarck’s Theory of Evolution Inheritance Of Acquired Traits – Traits Acquired During Ones Lifetime Would Be Passed To Offspring 44 Clipped ears of dogs could be passed to offspring! Lamarck’s Mistakes Did NOT Know traits were inherited (passed through genes) Mutation Occurs Before An Organism Is Born 45 Charles Darwin the Naturalist 46 Voyage of the Beagle Charles Darwin Born 1809 Joined Crew of HMS Beagle, 1831 Naturalist 5 Year Voyage around world 47 Darwin’s Voyage of Discovery A reconstruction of the HMS Beagle sailing off Patagonia. 48 Darwin Left England in 1831 Darwin returned 5 years later in 1836 49 The Galapagos Islands West of South America Animals On Islands Unique »Tortoises »Iguanas »Finches 50 51 The Galapagos Islands More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) different types of beaks adapted to their type of food gathering 52 53 Darwin’s Observations & Conclusions The Struggle for Existence 54 Evidence for Evolution – The Fossil Record 55 Definition • Evolution is the slow , gradual change in a population of organisms over time 56 Darwin’s Observations populations tend to remain stable in size Environmental resources are limited 57 Darwin’s Conclusion • Overproduction leads to a struggle for existence • Only a fraction survive each generation • Survival of the Fittest 58 Darwin’s Conclusion • most fit for environment leave more offspring 59 Darwin’s Theory of Evolution Organisms Change OverTime 60 Common Descent with Modification organisms descended from common ancestors diverge from a common form 61 Natural Selection Driving force for evolution struggle for resources, strongest survive & reproduce . 62 Natural Selection Cannot Be Seen Directly It Can Only Be Observed As Changes In A Population Over Many Successive Generations – Radiation – Fossil Record 63 Descent With Modification Takes Place Over Long Periods of Time Natural Selection Can Be Observed As Changes In – Body Structures – Ecological Niches – Habitats 64 Descent With Modification Species Today Look Different From Their Ancestors Each Living Species Has – Descended – With Changes – From Other Species – Over Time 65 Descent With Modification 66 Theory of Evolution Today Supporting Evidence 67 Homologous Structures 68 Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development 69 Similarities in DNA Sequence 70 Evolution of pesticide resistance in response to selection 71 Evolutionary Time Scales Macroevolution: Long time scale events that create and destroy species 72 Evolutionary Time Scales Microevolution: Short time scale events that change the genotypes and phenotypes of populations 73 Evidence of Evolution Key Concept Darwin Argued evidence Could Be Found In: – Fossil Record – Geographical Distribution of Species – Homologous Structures – Early Development 74 Fossil Record Earth is Billions of Years Old Layers of Rock Showed Evidence Of Gradual Change Over Time 75 Geographic Distribution Animals On Different Continents But Similar Adaptations 76 Homologous Body Structures Similar Structure Differ In Function Limb Bones Develop In Similar Patterns »Arms, Wings, Legs, Flippers 77 78 79 Homologous Body Structures 80 Analogous structures Butterflies or insects have wings but they are very different from the birds. 81 Copyright © The McGraw Hill Companies. Permission required for reproduction or display Anatomical studies show Vestigial parts – why does a whale have a pelvis and femur bones if it has no hind limbs? 82 Vestigial structures 83 Vestigial structures Human vestigial structures Ear muscles Wisdom teeth Appendix 84 Vestigial Organs Not All Serve Important Functions » Appendix In Man » Legs On Skinks 85 Similarities In Early Development Embryonic Structures Show Significant Similarities Embryo – early stages of vertebrate development 86 Human Fetus – 5 weeks 87 Chicken Turtle Rat 88 89