* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Origin of Diversity Notes
Objections to evolution wikipedia , lookup
Sociocultural evolution wikipedia , lookup
Natural selection wikipedia , lookup
Population genetics wikipedia , lookup
Evolving digital ecological networks wikipedia , lookup
Unilineal evolution wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Evidence of common descent wikipedia , lookup
Spontaneous generation wikipedia , lookup
Creation and evolution in public education in the United States wikipedia , lookup
Transitional fossil wikipedia , lookup
Paleontology wikipedia , lookup
The Descent of Man, and Selection in Relation to Sex wikipedia , lookup
Hindu views on evolution wikipedia , lookup
Creation and evolution in public education wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Acceptance of evolution by religious groups wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
Origin of Diversity notes KEY WORDS/ QUESTIONS Diversity Of Life: NOTES There is a tremendous diversity of life on Earth today. Look at virtually any environment and you will discover an incredible variety of plants, animals and other living things of all shapes, sizes and lifestyles. This leads to a 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. Evidence For: Against: Some observations seemed consistent 1. Maggots forming out of dead meat 2. Tadpoles forming from pond scum. 3. Microorganisms (or something) forming in broth solutions, stagnant water worms and algae Other observations supported the opposite: biogenesis (life from life) 1. Chickens come from eggs, eggs come from Origin of Diversity notes chickens 2. Calves come from cows, cows come from calves Note: Our observations and ability to observe limit our Ability to understand nature. Besides… Aristotle said that frogs and insects were generated by moist soil. Science like society was authority driven. Experiments Redi Redi (1600's) asked and attempted to answer the following causal question: 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 Origin of Diversity notes Similar experiments showed that many animals and plants come only from living ancestors Advent of Microscope Leads to Discovery of New world Late 1600s Anton van Leewenhook - ground lenses, made microscope, found microbes in water, pond scum, even own body... hypothesized that these too came from preexisting life. Argument revisited: 1700s Needham vs Spallanzani Argument wouldn't die, spontaneous generation still felt to be true in some places. Role of Hidden Agendae: Needham: Many have too much invested (prestige and professional standing) in old paradigm to give it up. 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 Origin of Diversity notes 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 Origin of Diversity notes Some concluding points: . evidence to reject abiogenesis once and for all. 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” 4. Scientific fraud, is always a possibility unless proper procedures are followed (peer review) So where does this leave us? Back to the other two: Abiogenisis is a rejected theory, but is still a theory 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….. Origin of Diversity notes 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: Evidence from Taxonomy: Conclusion: Note: Evidence from Embryology: Experiment? Hmm. Maybe we can infer using study of relationships between species 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 c. peripatus - annelids / arthropods d. Archaeopteryx – reptile to birds 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. 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. Origin of Diversity notes The more closely related two organisms are, the longer they resemble each other. Origin of Diversity notes Evidence from Anatomy: Homologies – homologous organs in two different species are derived a common ancestor. Homologies and Many times these organs are no longer useful and said to be vestigial. Examples include the hip and Vestigial organs 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. Convergent evolution: Conclusion: Evidence from biochemistry: In each case, we find different organs adapted to similar jobs. This results in convergent evolution – similar answers to similar problems. Doesn't necessarily reject all alternatives, BUT It is clearly consistent with evolution The closer related taxonomically (phylogenetically) two organisms are, the closer their chemistry & DNA are. Origin of Diversity notes Evidence from genetics and agriculture: We've been transmutating species for at least 10,000 yrs. 1. Prehistoric dairy farmer a. Can maintain five cows 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? Note: 2. Darwin called this "Artificial" selection. I like "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. Again demonstrates transmutability. Doesn't necessarily reject all alternatives, BUT clearly supports evolution Conclusion: 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 Origin of Diversity notes 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. Conclusion: KEY WORDS/ QUESTIONS Darwin’s conceptual framework: Most convincing support for evolution yet. Clearly rejects leading alternatives. NOTES 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. Origin of Diversity notes 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 Summary of Natural selection: 9. 1866, Mendel publishes his Theory of Particulate Inheritance 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. 5. Over long periods of time natural selection can both change existing species and create new ones. Biological Species: A natural population or group of interbreeding individuals which produce fertile offspring and are reproductively isolated. Origin of Diversity notes 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!! Important terms Convergent evolution (analogous structures) = similar answers to similar problems 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 Types of Selection: 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 Origin of Diversity notes Adaptive radiation: Adaptive radiation = the evolution of a number of diverse species specialized for survival in diverse environments (niches) Hardy Weinberg: Evolution won't occur if: 1. chance events do not effect gene frequency in a population 2. mutations don't occur or balance each other out 3. all genotypes have equal reproductive success; 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 Genetic drift: Speciation: a chance events that effect genetic frequencies (founder effect or log falls in the forest) macroevolution due to reproductive isolating Mechanisms. May be prezygotic (mechanical, temporal, ecological isolation, behavioral, chemical) also known as allopatry, or postzygotic (hybrid inviability = liger or mule). Chemosynthesis Inorganic molecules reacted with energy input from lightning etc. forming simple organic theory compounds (sugar, amino acids, nitrogenous bases, fatty acids). These then combined to form complex Origin of Diversity notes carbohydrates, proteins, lipids and nucleic acids. When these complex molecules were concentrated in pools they combined to form simple cells. Note Gradualism Vs Punctated Equilibrium Bottleneck Founder effect Chemosynthesis theory is not part of evolution. Evolution starts with life which is then shaped and diversified by natural selection. 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 Occurs when a population is drastically reduced and continues on from a few ancestors Occurs when a few individuals (not very diverse) give rise to a population …..Amish etc.