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Transcript
Today’s Plan: 10/15/09 • • • • Bellwork: Pre-lab (15 mins) Begin Natural Selection labs (40 mins) Notes (25 mins) Pack/Wrap-up (last few mins of class) Today’s Plan: 10/16/09 • • • • Bellwork: Vocab Quiz (20 mins) Finish Notes(25 mins) Finish Lab (the rest of class) Pack/Wrap-up (last few mins) Today’s Plan: 10/19/09 • Bellwork: Finish Natural Selection (15 mins) • Q&A Time (10 mins) • Natural Selection Quiz (as needed) • If you finish early, work on missing homework, finishing the lab, or getting ahead (the rest of the period) • Pack/Wrap-up (last few mins of class) Today’s Plan: 4/7/08 • • • • Bellwork: Finish Notes (15 mins) Q&A Time (5 mins) Change Through Time Quiz (as needed) When you finish, Finish the natural selection labs, then work on the classification Intro Activity (the rest of the period) • Pack/Wrap-up (last few mins of class) Evolution Historical Perspective • Before Darwin: – Jean Baptiste de Lamarck believed that organisms could change their bodies to fit the environment. Giraffe example. What is wrong with this idea? – Charles Lyell was building roads through rock, and discovered evidence that the earth was much older than the church believed. Found fossils in strange places Charles Darwin • Originally trained for the church • Studied science at school, and was a member of several scientific societies (Geology, zoology, etc.) • Read Lyell’s work • Took a job on the HMS Beagle as a naturalist traveling to South America and the Galapagos Islands for 5 years. Darwin (cont.) • Wasn’t the only one working on how species change over time. Another naturalist, Alfred Russel Wallace, was working with insect populations and simultaneously & independently had the same ideas as Darwin. • Darwin studied his collections and evidence over a very long period of time. When his hypothesis was formulated, he waited to publish his findings until he realized that Wallace was about to publish and get all of the credit. Darwin’s Evidence • Same species living on different islands w/ different habitats had different adaptations. • Noticed homologous (seen in different groups of descendants-ex. Hands/feet in primates) and analagous(same structure but different function structures in animals-ex. Wings/forelimbs). • Had read Thomas Malthus’ which said that food produces arithmetically while populations produce geometrically-There will be competition for resources. More Evidence • Vestigial Structures-once had a function but now reduced in size and function • fetal development • Fossil evidence Natural Selection • In On the Origin of Species, Darwin proposed “descent with modification” as a mechanism for species change. This later became known as natural selection. • Organisms with favorable adaptations will survive to reproduce longer and therefore pass on more favorable traits and their descendants will outnumber others. This takes lots of time. Eventually, as a result of this, species change (much different from Lamarck) Types of Natural Selection • Stabilizing-selecting for individuals with “middle” phenotypes. • Disruptive-selecting for individuals with phenotypes in the outer limits • Directional-selecting for individuals with phenotypes toward one limit or the other • Artificial-humans select for traits using selective breeding Making Species • Requires isolation and evolution in different directions • Originally thought to be slow and gradual (gradualism), now known to be stable, with short bursts of evolution (punctuated equilibrium) • Isolation can be because of a physical or behavioral barrier. – Physical requires geographic isolation. – Behavioral requires non-mating because of unrecognizable courtship rituals. Directions of Evolution • Species can evolve from a common ancestor in different directions (adaptive radiation), or come from different ancestry and move in similar directions (convergent evolution) • Coevolution-evolution at the same time in response to another species – the red queen hypothesis Genetic Equilibrium • Evolution works on genes to change whole species or populations of species over time, not on individuals. • Gene Pool=all of the genes of a population • Gene frequency=# or % of a certain allele in a population (p+q=1, p=dominant, q=recessive) • Using the present phenotypes, we can sometimes calculate the frequency of genes in the population. This helps us determine if populations are evolving or in equilibrium. • Hardy-Weinberg Theory for equilibrium: – p2+2pq+q2=1 – where p^2=homozygous dominant, q^2=homozygous recessive and pq=heterozygotes About Hardy-Weinberg • Theoretical and requires certain conditions – – – – – No immigration and emigration Random mating No net mutation No selection Large population • Has been shown to exist over time when the above conditions are met, however many populations don’t exist under these stable conditions • In other words, if the theory is an inequation, population change is occurring. Changes in equilibrium • Selecting mechanisms cause gene frequencies to change. • Immigration and Emigration mean that organisms bring in and take out new genes, which influences frequencies. • Catastrophic events that drastically reduce the gene pool also cause change (this is one example of genetic drift, which effects small populations more than large ones. Why?) Disclaimer • Evolution is a theory. It is not religion, not law, and not a hypothesis. • Evolution is based on scientific principles and evidence. Creationism is not based upon these principles and is therefore not a science. • Belief in God is based on faith, not science. Faith and science are two very different matters. Science does not seek to prove or disprove the existence of God. You do NOT have to believe in evolution, but it is a requirement of this course, set by the state. You must therefore learn it, and will be tested on it on the EOC. • If you have faith-based questions, I urge you to seek the advice of a minister, rabbi, priest, etc. This is their area of expertise, and they are far more qualified than I to help you. • If you have science-based questions, you are welcome to speak to me, because this is my area of expertise. Practice EOC Question • Which statement describes an exception to the cell theory? – Cells arise from previously existing cells – The Cell is the basic unit of function in animals – Mitochondria and chloroplasts can reproduce within the cell – The cell is the basic structure of plants Practice EOC questions: • Which of the following is a reactant in photolysis? – – – – Electron Oxygen Proton water • After performing a monohybrid cross, it is important to analyze the results with a Punnett square. Each box of a Punnett square represents– – – – A possible phenotype A possible genotype One individual Two possible genotypes Practice EOC question • Consider the following: – Mitochondria resemble bacteria – Mitochondria contain DNA and ribosomes – The ribosomes in mitochondria resemble those in bacteria • What would be a logical interpretation of these findings? – – – – There are many coincidences in nature Mitochondria might one day become bacteria Mitochondria evolved from a type of bacteria Cells evolved from mitochondria