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Transcript
16.1 and 16.2 (use worksheets) Important main points: a) What are Charles Darwin’s contributions to science? b) What are the three patterns of biodiversity that were noted by Darwin? What are examples of each? c) What is the importance of Hutton, Lyell, Lamarck, and Malthus in terms of shaping Darwin’s ideas? d) How is artificial selection different from natural selection, and how has artificial selection been used over time by humans? 16.3 Notes - Darwin Presents His Case Based on his experiences in travel, and research of other scientists’ data, he created a draft of his thoughts on _______________________ ________________________ but he waited _____________ years to publish it! Why so long? Because he saw the backlash that other scientists received for their ideas so he decided to wait and gather more _______________________ to support his ideas. What finally forced him to publish his work on evolution (On the Origin of Species)? Another scientists, Alfred Russell Wallace, was about to publish a book with the same thoughts as Darwin. He didn’t want to lose his credit so he was forced to publish early. His four main points 1) The Struggle For Existence a) Based on reading ______________________ he explains that if there are more organisms born then the environment can provide space/food for some will live while others will _______________. This brings up the important question of who survives and who doesn’t? Darwin states that those overall _____________________________________ for their environment (the fittest) will survive. b) The more ____________________ the environment the more organisms it can hold (Harsh desert vs. thriving jungle) 2) Variation and Adaptation a) Due to ______________________ reproduction all offspring will be genetically different and will provide genetic variations into a population. Those variants that are better suited for their ___________________________ will survive. b) Those that survive will then pass on those better suited traits onto their _______________________. i) Any heritable characteristic that increases an organism’s ability to survive and reproduce in its environment is called an _________________________________. coloration, claws, wings, camouflage, mimicry, etc 3) Survival of the Fittest a) Darwin used the term “____________________” to give a level to how well suited an organism was for its environment. Those with ____________ fitness are well suited to their environment and can survive and reproduce at high rates. However those with ______________ fitness are not suited to their environment and reproduce at very low levels. (few offspring is bad!) i) Question: If an organism produces many offspring, but none of them reach maturity, do you think the organism has high or low fitness? Explain why. ______________________________________ _______________________________________________________________________________ _______________________________________________________________________________ b) He summed up all of this with his term survival of the _______________________ where survival means having the ability to pass on your genetics and adaptations to future generations. 4) Natural Selection a) In natural selection the ________________________ influences fitness. b) Natural selection occurs when: i) More individuals are _________________ than can __________________. ii) There is natural heritable _____________________________. iii) There is variable _______________________ among individuals. c) Those with the highest fitness will adapt and ________________ and those with the lowest fitness will _______________ off. d) Natural selection only works for ________________________ traits. Note that this is not the ONLY mechanism driving evolution… more to come! 5) Descent with modification a) He proposed that over time new species form that are _______________________ forms of their descendents. b) He used evolutionary __________________ to show how different species came from one original descendent. According to this principle all organisms are descended from ancient common ______________________. 16.4 Notes – Evidence of Evolution 1) Important Points: a) Evolution = _____________________ b) The mechanism of how organisms change over time = ________________________ (it is testable/falsifiable) c) Also evolution is not about ________________ it is about _____________________. 2) Biogeography is the study of where organisms live ____________ and where they lived in the __________. a) The patterns formed in the distribution of living and _________________ species tell us how modern organisms evolved from their ancestors. (movement, environment, etc.) b) Many __________________ discovered fossils, are filling in the fossil record, and helping to complete the tracing of evolution of _____________________ species from extinct ancestors. 3) Homologous Structures a) A clue to common ______________________ from an ancient ancestor. b) Common ___________________, but NOT common _____________________. c) See example to the right: d) This is synonymous (similar in definition to) ________________________ evolution. Divergent evolution is the accumulation of differences between groups which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection. 4) Analogous Structures a) This is not a form of common descent. b) Body parts that share common _________________________, but NOT ___________________. c) Ex: wing of a bee vs. wing of a bird. Both _______________, but they are not built nearly the same. Both acquired the wing to help with flight. d) This is synonymous with _____________________ evolution. Convergent evolution describes the acquisition of the same biological trait in unrelated lineages. 5) Vestigial Structures a) Structures that are passed from generation to generation but have no _________________ use. i) Ex: Dolphins hip bones ii) Ex: Wings of the flightless cormorant iii) Ex: Legs of the Italian three-toed skink (it moves by slithering like a snake) iv) Ex: Human appendix v) Ex: tiny skin covered eyes of a Blind Mole Rat b) Why do organisms keep these if they are not of use? i) Scientists are not 100% sure but the current theory is that the presence of the structure does not hurt the organisms _______________________ level for survival and therefore natural selection doesn’t act quickly to eliminate it. 6) Embryology a) In the picture to the right the top row is the actual organism where the bottom row is an artistic rendering pointing out significant features. How are the different pictures across the top similar? How are they different? _________________________ __________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ b) Do you think they all come from the same lineage of organism? Why or why not? ____________________________________________________________________________________ ___________________________________________________________________________________ 7) Life’s Common Genetic Code a) The strongest evidence for descending from a common ancestor is based on ____________________. b) The Human Genome Project has coded the genetics of a vast number of organisms and guess what? We are all VERY ____________________. To the point where the genetic code is nearly identical in almost all organisms (bacteria, yeasts, plants, fungi, and animals). There must have been a common ancestor at one point in order for this to happen. IMPORTANT note on 16.4: you need to use the book to read on the Grants finches, biogeography, and genetics 17.1, 17.2, and 19.2 Notes 1) Evolution, in genetic terms, involves a change in the frequency of _____________________ in a POPULATION over time. a) If the frequency of an allele is increasing or decreasing it means that a population is evolving. Judged by looking at the gene pool of populations genes. 2) Natural Selection vs. Evolution a) Natural Selection happens to __________________________, but the changes that it causes in the allele frequency shows up in the _______________________________ as evolution. b) IMPORTANT: The smallest unit that can evolve is a _________________________ NOT individuals. 3) 3 Sources of Genetic Variation a) Mutations b) Genetic Recombination in Sexual Reproduction (passing from parents to offspring) c) Lateral Gene Transfer (important for single celled organisms where they swap genes through plasmids) 4) Single Gene vs. Polygenic Traits a) Single Gene traits are much more ____________________ as they only involve one gene and can lead to allele frequency changes faster. b) Polygenic Traits require more than one gene and therefore take a much _____________________ time to affect the allele frequency. 5) Natural Selection acts on Variations a) Stabilizing selection- natural selection that favors the ______________________ individuals in a population. (Average birth mass of baby survives!) b) Disruptive selection- individuals with either _______________________ of a trait’s variation are selected for to survive. The _________________________ phenotype tends to be eliminated. (small and large beak size survives if small/large seeds are in abundance) c) Directional selection- natural selection that favors ____________ of the _________________ variations. (woodpecker with longer beak survives since it can get food easier from tree) Note: species are organisms that look alike and can interbreed to produce fertile offspring. i) Geographic Isolation: ________________________________ may prevent this reproduction from happening. A volcano eruption or a river may isolate a species. Therefore, a _________ species may evolve. These new organisms adapt to their new environment and start their own gene pools. ii) Reproductive Isolation: Different ___________________________ and the ability to fertilize an organism of the same species could also result in speciation. NOTE: speciation means to form a new species. iii) Nondisjunction: Changes in ____________________________ number can also cause speciation, which is seen in wheat and apples. 6) 2 Theories about Evolution - Speciation can occur quickly or slowly a) ___________________________- species originate through a gradual change of adaptations slowly. b) ___________________________ equilibrium- speciation occurs quickly in rapid bursts due to changes in geography, climate, predators. *****Both views are supported by fossil evidence***** 7) Background Extinction vs. Mass Extinction a) _______________________ extinction is coined “business as usual” extinction because there is a natural competition of evolution and survival over a longer period of time. b) Whereas _______________ extinction is a relatively rapid extinction where entire ___________________________ vanish, whole food webs collapse, species go extinct due to ________________ loss, and the process of natural selection just cannot compensate quickly enough. i) What can cause these extinctions? _________________________, global climate change, volcanoes, moving ________________________, and changing ________________ levels. ii) After this many species go extinct which leaves space for other species to take over. This rebuilding can take anywhere from 5 to 10 ________________ years. 8) Adaptive Radiation a) This is the process by which a single _______________ or a small group of species evolve over a relatively ________________ period of time into several different forms that live in ________________________ ways. i) This is what Darwin discovered in the finches on Galapagos Island. b) After the ____________________ went extinct an adaptive radiation occurred which brought a large variety of organisms into the population. 9) Coevolution a) When two different __________________ are so closely linked that they evolve together. b) Ex. of a GOOD relationship: Flowers and Pollinators i) Flowers need to pollinate and ___________________ (ex: bees, moths, etc.) want the nectar inside the flower. Pollinators will adapt to best retrieve the nectar and in turn by more pollinators being able to get the nectar the flower will pollinate more often. c) Ex. of a BAD relationship: Plants and Herbivores i) Herbivores like to eat plants. Over time plants have evolved bad-tasting or poisonous compounds that keep herbivores from eating them. In response the herbivores will adapt to be able to be _____________________ to such poisons (or even be able to store it in their tissues to ward off predators). And so the cycle continues. (1) NOTE: this relationship that has caused plants to be so poisonous has created some of the most ______________________ natural poisons used by humans.