2 Pre-class Question 5/21/09Why were the beaks of the finches that Darwin observed on the Galapagos Islands different on different islands?Homework (due Friday)Active Reading “Developing a Theory”
3 A broad explanation that has been scientifically Developing a TheoryEvolution is the process by which species change over time.Charles Darwin was responsible for developing the modern theory of evolutionA broad explanation that has been scientificallytested and supported
4 3 Types of Selection Artificial Selection Humans can choose what traits are favorable in a species and breed plants and animals to have these traitsNatural SelectionThe process by which individuals that are better adapted to their environment survive and reproduce more successfully than those that are less adapted to do so.
5 3 Types of Selection Continued Sexual SelectionAn evolutionary process by which a mate is chosen on the basis of a particular trait
6 It’s Who You Know and What They Know Darwin came up with the theory of evolution based on his observations and those of others:LamarckObserved that each organism is usually well adapted to its environment.MalthusIn 1798,Malthus observed that human food supply was increasing at a slower pace than the human population and hypothesized that many humans would die off due to disease, war and famine.LyellGeologist that though that processes such as erosion and the formation of fossils was gradual and constant.
7 Evolution by Natural Selection Darwin’s theory predicts that over time, the number of individuals that carry advantageous traits will increase in a populationStep1 OverproductionEvery population is capable of producing more offspring than can possibly survive.Step 2 VariationVariation exists in every population in the form of inherited traits.Step 3 SelectionBased on traits one individual is more likely to survive than another and reproduce.Step 4 AdaptationOver time, those traits that improve the survival and reproduction will become more common.
8 Pre-class Question 5/27Why do you think that giraffes evolved to have long necks?What is the selective pressure that caused this change to occur?Hint: Selective pressure is any phenomena which alters the behavior and fitness of living organisms within a given environment.HomeworkStudy for Chapter 16 Vocab Quiz (Friday, 5/29)
9 Darwin – The Origen of Species by Natural Selection Darwin presents evidence of evolution from multiple fields of science, where some species of animals have common characteristicsThe Fossil RecordThe study of fossils or traces of living things from the pastBiogeographyThe study of the location of organisms around the world.Developmental BiologyThe development of organisms from embryosAnatomyThe study of bodily structure of animalsBiochemistryThe study of biomolecules such as amino acids and DNA
10 Evaluating Darwin’s Ideas – 3 major strengths Evidence of evolutionA mechanism for evolutionNatural SelectionThe recognition that variation is importantPrior to Darwin’s theory, species were classified byCommon appearance, and ignored variation whichWas a starting point for evolution
11 Evaluating Darwin’s Ideas – Weaknesses Inherited variation was important to Darwin’s theory, but he did not have a clear idea of how traits were inherited. He did not have an understanding of genetics.There was roughly 100 years between when Darwin published his theory and the structure of DNA was discovered.
12 Reading Selection: How Do Species Change Over Time? Pre-Class 5/28Take out yesterday’s activityReading Selection: How Do Species Change Over Time?HomeworkStudy for tomorrow’s chapter 16 vocab quiz
13 Studying Evolution at all Scales Change in the genes of a populationThe formation of new species as a result of evolutionThe appearance of new species over time
15 Processes of Microevolution (5) Natural SelectionMigrationMate ChoiceCan be random or through sexual selectionMutationThe numbers and types of alleles can change from generation to generation although it is rareGenetic DriftGenetic drift affects genetic makeup of the population through an entirely random process..
16 Patterns of Macroevolution (6) Covergent EvolutionWhen evolution is strongly directed by the environment, species living in a similar environment should evolve similar adaptations.CoevolutionSpecies that share an environment can affect each others evolution. They develop adaptations to coexist
17 Patterns of Macroevolution Cont. Adaptive RadiationSpecies splint into two or more lines of descentExtinctionGradualismMany small changes occur gradually over timePunctuated EquilibriumNew species suddenly appear after some environmental change.