KEY WORDS/



| KEY WORDS/ |NOTES |

|QUESTIONS | |

|Diversity |There is a tremendous diversity of life on Earth today. Look at virtually any environment and you will discover an |

|Of |incredible variety of plants, animals and other living things of all shapes, sizes and lifestyles. This leads to a |

|Life: |causal question, |

| |CQ = How did all this diversity arise? |

|Theories on the origin of diversity: |Theories about the origin of diversity fall into three main categories: |

| |1- Spontaneous Generation, 2-Special Creation, |

| |3-Transmutation of Species = Evolution |

| | |

|Abiogenesis |Abiogenesis is also known as Spontaneous Generation. It means life emerging from non-living materials in a spontaneous |

| |manner. This was the ruling theory in Europe for over 1000 years. |

| | |

| |Some observations seemed consistent |

| |1. Maggots forming out of dead meat |

|Evidence |2. Tadpoles forming from pond scum. |

|For: |3. Microorganisms (or something) forming in broth solutions, stagnant water ( worms and algae |

| | |

| |Other observations supported the opposite: biogenesis (life from life) |

| |Chickens come from eggs, eggs come from chickens |

|Against: |Calves come from cows, cows come from calves |

| | |

| |Our observations and ability to observe limit our |

| |Ability to understand nature. |

| | |

| |Aristotle said that frogs and insects were generated by moist soil. Science like society was authority driven. |

|Note: | |

| | |

| | |

|Besides… | |

|Experiments |Redi (1600's) asked and attempted to answer the following causal question: |

|Redi |Where did these maggots in my meat come from? |

| | |

| |Possible explanations: |

| |a. Spontaneous generation =abiogenesis |

| |b. Biogenesis = life comes from preexisting life |

| |(1) We know the maggots turn into flies |

| |(2) Where must maggots have come from: flies |

| | |

| |Experiment to tell the difference between the two: |

| |Put piece of meat into two sets of jars, Draw |

| |covered 1 with cloth but not the other |

| |Predictions |

| |- under spontaneous generation: maggots in both |

| |- under biogenesis: no maggots in covered jar |

| |Results: maggots only in the uncovered |

| |Conclusions: Support biogenesis |

| |Reject: abiogenesis |

| | |

| |Similar experiments showed that many animals and plants come only from living ancestors |

|Advent of Microscope |Late 1600s Anton van Leewenhook - ground lenses, made microscope, found microbes in water, pond scum, even own body... |

|Leads to Discovery of |hypothesized that these too came from preexisting life. |

|New world | |

| | |

|Argument revisited: |1700s Needham vs Spallanzani |

| |Argument wouldn't die, spontaneous generation still felt to be true in some places. |

|Role of Hidden Agendae: | |

| |Many have too much invested (prestige and professional standing) in old paradigm to give it up. |

|Needham: | |

| |Needham: 1748 (English clergyman) |

| |Observation: broth spoils or "goes bad" |

| |Possible explanations: “vitalism” (life force) vs |

| |biogenesis |

| |Experiment: put mutton gravy in a corked |

| |container & boiled briefly. Draw |

| |Predictions: Vitalism: microbes and spoiling, |

| |Biogenesis: no microbes or spoiling |

| |Results: microbes and spoiling |

| |Conclusion: supports vitalism, rejects biogenesis |

| | |

|Spallanzani: |Said, “Wait a minute, you have problems”: |

| |You used a crudy old cork and you probably didn't boil it long enough. So he offers his own test: |

| | |

| |Same observation: thing go bad |

| |Possible explanation: same as above |

| |vitalism vs biogenesis |

| |Experiment: (Draw): |

| |prepared flasks of gravy, boiled for an hour then melted top to seal |

| |Predicitions: Vitalism: still spoil |

| |Biogenesis: not spoil |

| |Results: no microbes or spoiling unless opened |

| |Conclusion: rejects vitalism, supports biogenesis |

| | |

|Needham's reaction: |Did he roll over and play dead? No, remember hidden agenda. Instead he said that, “the life force in the air" was |

| |destroyed by sealing bottles. That life force needs “elastic air” to operate. |

| |Needham and Spallanzani argued about methods and the "elasticity of air" for years. |

|Final resolution: |Louis Pasteur 1862 – created "S" shaped open flasks (Draw) and partially filled with broth then boiled. The flasks did |

| |not spoil. In fact some were displayed for 80 years before finally being sealed. |

| | |

| |When flasks were tipped allowing some of the fluid into the trap and back: they quickly became infected became infected. |

| |This provided convincing evidence to reject abiogenesis once and for all. |

|Some concluding points: |1. Scientists don't always agree on everything. |

| |2. When they disagree, they often resort to arguing methods |

| |3. The role of biases |

|. |a. We usually have them |

| |b. In my work, I thought I saw one hypothesis |

| |which seemed more logical /explaining more |

| |c. What happens when special interests fund |

| |research (i.e. Tobacco Research Institute |

| |claimed for thirty years that “cigarettes don’t |

| |cause cancer” |

| | |

|So where does this leave us? |4. Scientific fraud, is always a possibility unless proper procedures are followed (peer review) |

| | |

| |Abiogenisis is a rejected theory, but is still a theory |

|Back to the other two: |since it attempts to explain the origins of diversity. |

| | |

| |Religion caveate - there is a difference between scientific and religious hypotheses and theories. |

| |Religious theories rely on faith for acceptance. |

| |Scientific theories rely on scientific testing and falsifiability for acceptance. |

| | |

| |If a religious theory is not testable & falsifiable, it is not scientific. That does not necessarily mean it is wrong…..|

| | |

| | |

| |Teaching religious theories in public school is a violation of the establishment clause of the U.S. Constitution… We will|

| |not be discussing Special creation, at least not directly. |

|Observation: | |

|Causal Question: |There is diversity…. Why? |

|Explantion: |Transmutation / Evolution |

| | |

|Experiment: |Experiment? Hmm. Maybe we can infer using |

| |study of relationships between species |

|Evidence from Taxonomy: |1. Not all individuals within a species look the same (there is variance) |

| |2. Between species, we often find intermediates |

| |a. Rattlesnakes, Elapids, rear fanged colubrids |

| |Draw on back |

| |b. lizards- legless lizards/boas-snake |

|Conclusion: |c. peripatus - annelids / arthropods |

| |d. Archaeopteryx – reptile to birds |

|Note: |Doesn't necessarily reject all alternatives, BUT |

| |It is consistant with evolution. |

| |Variation within a species says something about transmutability or the ability to evolve. |

|Evidence from Embryology: | |

| |Embryology = the study of the development of organisms from zygote to adult. |

| | |

| |“Ontogeny recapitulates phylogeny” claim was that organisms went through all the body forms of their ancestors as they |

| |developed. |

| |Not true, actually organisms go through similar larval stages as their close (evolutionary) relatives. |

| |The more closely related two organisms are, the longer they resemble each other. |

|Evidence from Anatomy: |Homologies – homologous organs in two different species are derived a common ancestor. |

| | |

|Homologies and Vestigial organs |Many times these organs are no longer useful and said to be vestigial. Examples include the hip and thigh bones in |

| |snakes and whales and the tail bone and appendix in man. |

| | |

| |How are these useful to other organisms? |

| |Appendix of man = blind end pouch full of bacteria which can become infected. Appendix of Gorilla used to help digest |

| |leafy vegetarian diet. |

| | |

|Analogies |– analogous organs have similar form and function but were derived from different ancestors. |

| | |

| |These organs serve a useful purpose. Examples include the fluke of a whale and the tail of a fish, penguin “wings” and |

| |fish fins, wing of a bat / wing of a bird vs insect wing. |

| | |

| |In each case, we find different organs adapted to similar jobs. This results in convergent evolution – similar answers |

| |to similar problems. |

|Convergent evolution: |Doesn't necessarily reject all alternatives, BUT |

| |It is clearly consistent with evolution |

|Conclusion: | |

| |The closer related taxonomically (phylogenetically) two organisms are, the closer their chemistry & DNA are. |

| |We've been transmutating species for at least 10,000 yrs. |

|Evidence from biochemistry: |1. Prehistoric dairy farmer |

| |a. Can maintain five cows |

|Evidence from genetics and agriculture: |b. If they all have calves, how many will he have? |

| |c. Only some should be permitted to reproduce |

| |d. Alternatively, you eat some and keep others |

| |Which calves do they keep? |

| | |

| |2. Darwin called this "Artificial" selection. I like |

|Note: |"Human directed" better |

| |3. Darwin cited many examples with pigeons. |

| |4. Man has done this repeatedly with dogs, cats, |

| |cattle, horses etc. |

| |5. Cabbage, cauliflower, brussel sprouts all started |

| |out as same plant. |

|Conclusion: |Again demonstrates transmutability. |

| |Doesn't necessarily reject all alternatives, BUT |

| |clearly supports evolution |

| | |

|Fossil evidence: |Fossil record: Draw how fossils are formed etc |

| |NOTE, there are no gaps that we wouldn't expect to find due to need for specimens to be rapidly buried in sediment |

| |plus soft tissues are poorly preserved |

| | |

| | |

| | |

| | |

| | |

| | |

|Grand Canyon fossil record: |Natural laboratory to test evolution. |

| |Draw on board. |

| | |

| | |

| | |

| | |

| | |

|Predictions | |

|for Evolution: | |

| |We should find a slow gradual increase in complexity and diversity. |

|for Abiogenesis: | |

| |There should be no real pattern in complexity and diversity. Species should appear and disappear at random. |

| | |

| |Most convincing support for evolution yet. Clearly rejects leading alternatives. |

|Conclusion: | |

|KEY WORDS/ |NOTES |

|QUESTIONS | |

|Darwin’s conceptual framework: |1. Malthus essay on population – gave Darwin idea of Biotic Potential = ability of organisms to produce more offspring |

| |than environment can support. This leads to a struggle for survival |

| | |

| |2. Geology – Theory of Gradualism (Hutton 1795), Form of Earth due to slow gradual change, not through a few |

| |catastrophies. |

| | |

| |3. Uniformitarianism (Lyell 1830) same processes that work |

| |today worked in past |

| |4. Lamark 1809, theory of inheritance of acquired characteristics (i.e giraffe’s neck) |

| |5. Voyage of Beagle (1831-1836) |

| |Darwin was the ships “naturalist” |

| |6. Darwin writes of transmutation 1837 |

| |Informal notes to friends |

| |7. Wallace writes to Darwin (1858) and publishes |

| |essay on natural selection. |

| |8. Darwin publishes On the Origin of Species, 1859 |

| | |

| |9. 1866, Mendel publishes his Theory of Particulate |

| |Inheritance |

|Summary of Natural selection: |1. Organisms alive today are the result of evolution |

| |not special creation |

| |2. More organisms are produced than can survive = |

| |Biotic potential. Resources are limited, leads to |

| |a struggle for survival “survival of the fittest” |

| |3. Characteristics vary and can be inherited. |

| | |

| |4. Some traits are better adapted and leave |

| |more offspring. |

|Biological Species: |5. Over long periods of time natural selection can |

| |both change existing species and create new ones. |

| | |

| |A natural population or group of interbreeding individuals which produce fertile offspring and are |

| |reproductively isolated. |

|Biological Significance: |Since evolution from a shared ancestors has shaped organs and physiology from worms to humans we can learn about |

| |ourselves by studying bacteria, dogs, rats..... also.... since ecological assembleges of plants and animals have |

| |evolved together over time, many features of their physiology are intimately interconnected in ways that we do not yet |

| |understand and ignore at our own peril!! |

| | |

| |Convergent evolution (analogous structures) = similar answers to similar problems |

| | |

|Important terms and concepts… |Evolutionary arms race ie. parasitism, predation, |

| |herbivory drive evolution |

| |Evolutionary fitness determined by the size of an organisms reproductive output |

| | |

| |Evolutionary adaptation = a form of a trait increases fitness, can be physical, chemical or behavioral |

| | |

| |Stabilizing selection - keeps phenotypic values steady, usually around median |

| | |

| |Directional selection - shoves average value towards one extreme or other. |

| | |

| |Disruptive selection - shoves values away from mean towards extremes, can lead to speciation |

|Types of Selection: |Adaptive radiation = the evolution of a number of |

| |diverse species specialized for survival in diverse environments (niches) |

| | |

| |Evolution won't occur if: |

| |1. chance events do not effect gene frequency in a |

|Adaptive radiation: |population |

| |2. mutations don't occur or balance each other out |

| |3. all genotypes have equal reproductive success; |

|Hardy Weinberg: |ie. no natural selection is operating on population |

| |4. no net flow of alleles (genes) in or out of pop |

| |(no migration or imigration) |

| |5. all mating in population is at random |

| | |

| | |

| |a chance events that effect genetic frequencies (founder effect or log falls in the forest) |

| | |

|Genetic drift: |macroevolution due to reproductive isolating Mechanisms. |

| | |

| |May be prezygotic (mechanical, temporal, ecological isolation, behavioral, chemical) also known as allopatry, or |

|Speciation: |postzygotic (hybrid inviability = liger or mule). |

|Chemosynthesis theory |Inorganic molecules reacted with energy input from lightning etc. forming simple organic compounds (sugar, amino acids, |

| |nitrogenous bases, fatty acids). These then combined to form complex carbohydrates, proteins, lipids and nucleic acids. |

| |When these complex molecules were concentrated in pools they combined to form simple cells. |

| | |

| |Chemosynthesis theory is not part of evolution. Evolution starts with life which is then shaped and diversified by |

| |natural selection. |

|Note | |

| |Darwin said it took millions of years for one organism to evolve into another. The Cambrian fossil record shows that |

| |evolution may have long periods of relatively no change followed by periods of rapid speciation triggered by drastic |

| |climatic change |

|Gradualism | |

|Vs |Occurs when a population is drastically reduced and continues on from a few ancestors |

|Punctated Equilibrium | |

| |Occurs when a few individuals (not very diverse) give rise to a population …..Amish etc. |

| | |

|Bottleneck | |

| | |

| | |

|Founder effect | |

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