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UW-Milwaukee BIOSCI 100 - Evolution

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BIO SCI 100 1st Edition Lecture 1 Outline of Current Lecture I. Evolution II. Theories are Tested and ModifiedIII. The History of Evolutionary ThoughtIV. Evidence for Darwin’s Ideas about EvolutionCurrent LectureI. Evolution 1• Greek: Zoon = “animal”, Logos= “study of”• Zoology is the biological study of animals, including:o Diversityo Evolutiono Formo Function -physiology & organ systemso Interaction with other animals and the environmentThe Scientific Method• The “Scientific Method”o Also referred to as the Hypothetico- deductive method• Contains two components:o Hypothesis: a possible explanation of observations must be testable and falsifiableo Theory: general principle or explanation of observed facts supported by substantial amount of evidenceThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Answer a question using the scientific method:• Step 1: A question arises based on observations of natural phenomena.• Step 2: Generate a hypothesis, which is a potential answer to the question.• Step 3: Collect data or conduct an experiment to test your hypothesis.• Step 4: Based on data support or falsify your hypothesis• Step 5: If enough evidence supports the hypothesis, it may become a theory.Using the Scientific Method: An Example• Step 1: Why do giraffes have long necks?• Step 2: Hypothesis: Long necks help them acquire food high in the trees.• Step 3: Collect data. Find that most feeding is done at shoulder height.• Step 4: Based on collected data, we falsified the hypothesis.• Generate a new Hypothesis!II. Theories are Tested & ModifiedSolar System:1. Geocentric Theory: the sun revolves around the earth2. Heliocentric Theory: the earth revolves around the sun; the sun is the center of our solar system; proposed first by Copernicus & Galileo in the 1500's.Position of the Continents:1. Continent location is fixed.2. The theory of continental drif suggested that the continents moved.3. The theory of plate tectonics suggested how the continents moved.III. The History of Evolutionary ThoughtFour scientists important to the Theory of Evolution: Lamarck, Lyell, Darwin & WallaceEvolution: Organisms change over timePre-Darwinian Ideas• Lamarck---Lamarckism:o Use and Disuse: Useful structures grow largero Inheritance of acquired traits: individuals acquire modifications that are passed onto offspringEx: Giraffe's long neck stretched, to eat foodEx: Muscle building by lifing weightsNOTE: first scientific explanation for evolution, but the mechanism was incorrect.• Lyell: Geologist• Established uniformitarianism1. Laws of physics and chemistry are constant over time2. Past geological events occurred by same natural process existing in presento Stressed the slow pace of geologic change over timeo Based on evidence from fossils, estimated that the earth was millions of years old.Darwin's Ideas• From 1831-1836 Darwin (22 years old) was ship naturalist on the HMS Beagle• Darwin observed & studied animals, fossils, and habitats on continents and islands around theworld.The Galapagos Islands• Darwin’s Observations of the Galapagos Islands: Tortoiseso Variation in traits between islandso Also, variation between islands and the South American mainland• Darwin's Hypotheses:1. Modification of traits was important to survival and reproduction2. Development of new species from old species occurred by an accumulation of changes over timeFive Components of Darwin's Theory of Evolution• 1.Perpetual change: the living world is always changing; changes occur across generations.• 2.Common descent: all forms of life descended from a common ancestor• Species that have more recent common ancestors will be more closely related.• 3. Multiplication of species: evolution produces new species by changing old species.• 4.Gradualism: Large differences in anatomical traits characterize species; they result from accumulation of small changes over a long period of time.• 5. Natural selection: The process by which populations accumulate favorable traits (adaptations) that allow them to survive & reproduce in their environment• 1859: Darwin published “Origin of Species”, the book that proposed natural selection as the mechanism for evolution5 Observations of Natural Selection• 1. Organisms have great potential fertility.o All populations could potentially produce large numbers of offspring in each generation• 2. Natural populations do not increase exponentially in size, but remain fairly constant, unlessthey become extincto No natural population shows the exponential growth that theoretically could occur due to their reproductive ability.• 3. Natural resources are finite.o If natural resources were unlimited, natural populations could grow exponentially.THUS: There is a struggle for survival among offspring and only some offspring will survive to reproduce• 4. All individuals show variation in traits.o No two individuals are exactly alike. They may vary in weight, color pattern, behavior etc.• 5. Variation in traits is heritable and can be passed on to offspring.o Darwin did not understand how this occurred, but today we know it’s due to DNA as genes being passed from parents to offspring.IV. Evidence for Darwin’s Ideas about Evolution Perpetual Change•Fossil record: mineralized remains of past life buried in the Earth’s Crust.• Evidence of perpetual and gradual change in species and environment over geologic time.Geologic Time•The Law of Stratigraphy: lower layers of sedimentary rock are older than upper layers.o Is a relative measure and did not give an accurate estimate of age.• In 1940s, radiometric dating was developed:• Determined absolute age of rock or fossil by measuring the decay of atoms (Carbon & Nitrogen) within the rock.• Showed that macroscopic organisms appeared at the start of the start of the Cambrian period,600 million years


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