LAB:Variation in a SpeciesSlide 2Slide 3What is a species?What is a population?What is a gene pool?Hardy & WeinbergSlide 8Slide 9Slide 10Slide 11Slide 12Slide 13Observing VariationSlide 15Slide 16Slide 17What is this Process?Why was this little sticker so controversial?Understanding EvolutionEvolution by Natural SelectionCharles DarwinSlide 23Slide 24Cape Verde and Galapagos ArchipelegosGalapagos Islands and South American MainlandIntra-Galapagos Variability: Darwin’s FinchesDarwin saw patterns among a diverse, extensive array of fossils & specimens (worked on it for a couple decades!)Common Ancestor The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.Darwin’s NotebookSlide 31Slide 32Jean Baptiste de LamarckSlide 34Slide 35Lamarck and Wallace: How would they explain these observations?Slide 37Slide 38Slide 39Slide 40Slide 41The Modern Synthesis 1932-1953How can allele frequency change?How can evolution occur?Evidence that evolution takes placeSlide 46Homologous StructuresSlide 48Slide 49Embryo HomologySlide 51Plant embryo homologySlide 53Slide 54Slide 55Slide 56Evolution: Changes in allele frequency over timeSlide 58Slide 59Slide 60BiogeographyHawaiian Monk SealsCommon AncestorSlide 64Whale evolutionHardy-Weinberg genetic equilibriumGenetic Drift: The Founder EffectGenetic Drift: Bottleneck EffectNatural SelectionSlide 70Slide 71How to form new SPECIES?Adaptive Radiation – process by which a single species evolves into several different forms that live in different waysConvergent Evolution – process by which unrelated organisms independently evolve similarities when adapting to similar environments.Slide 75LAB:Variation in a Species•What is the purpose of Part 1?•(Measuring Pumpkin seeds)•There is variation in size in Pumpkin plants. Variation can be measured.LAB:Variation in a Species•What is the purpose of Part 2?•(Calculate how long it takes pumpkin plants to take over the Earth)•There are reasons to explain why pumpkin plants have not ever taken over the EarthLAB:Variation in a Species•What is the purpose of Part 3?•(Effect of predators on sweet cute Bonitos)•There are reasons to explain why the population of bonitos on one island look different from bonitos on another islandWhat is a species?•A group of living things that•are similar,•and can breed together in nature•to produce fertile offspring.What is a population?•A group of living things that•belong to the same species,•live in the same area,•and can reproduce together.What is a gene pool?•The total collection of genes in a population at any one time.Hardy & Weinberg•What is allele frequency?•1908: Hardy and Weinberg invented the term “allele frequency” to describe the percentage of dominant and recessive alleles found in a populaton.Hardy & Weinberg•How is allele frequency measured?•Example: a lizard population might have the following allele frequency for the alleles F and f:•FF = 0.64 (64%)•Ff = 0.32 (32%)•ff = 0.04 (4%)Hardy & Weinberg•What is genetic equilibrium?•1908: Hardy and Weinberg invented the term “genetic equilibrium” to describe a population in which the frequency of alleles stays the same from one generation to the next.Hardy & Weinberg•How was genetic equilibrium measured?•Hardy-Weinberg equations:•p2 + 2pq +q2 = 1•p + q = 1Hardy & Weinberg•Hardy-Weinberg Equations•Where p2 is the frequency of homozygous dominant individuals•Where 2pq is the frequency of heterozygous individuals•Where q2 is the frequency of homozygous recessive individualsHardy & Weinberg•What causes genetic equilibrium?•There must be…….•A large population•Members mating at random•No mutation•No migration•No natural selectionHardy & Weinberg•What can cause allele frequency to change?•Migration (also called gene flow)•Mutation•Mate selection (non-random mating)•Predators, disease, famine, drought, storms, accidents.Observing Variation•(1) Variation exists in living populations.•(2) Some variations are helpful and increase life span.•(3) Some variations are harmful and decrease life span.Observing Variation•(4) A population may become physically separated, so two groups form.•(5) As mutations and meiosis occur, new variations will appear.•(6) Some offspring will survive better than others.Observing Variation•(7) Offspring that survive in one area may not survive in another area.•(8) Over time, more variations will accumulate in the two populations.•(9) The two populations will become different because different variations occur in the two groups.Observing Variation•(10) Individuals that die out do not get to reproduce.•(12) Sometimes, a new species has formed.•(11) In some cases, the two groups become so different from each other that they can no longer interbreed.What is this Process?•Evolution of species•A set of natural processes that causes change in a population of living things over time.•Biological evolution, simply put, is descent with modification.Why was this little sticker so controversial?Source: http://www.swarthmore.edu/NatSci/cpurrin1/textbookdisclaimers/CobbDisclaimer.jpgUnderstanding Evolution•Scientists study natural processes and look for natural explanations.•I will introduce you to some of the evidence that leads biologists to view evolution as the great unifying theory of the field.•Science cannot answer every question.•What if you disagree with photosynthesis?Evolution by Natural Selection•Variation exists in every population.•Natural selection (predators, disease, drought, cold, famine, flood, heat…..) causes some individuals to survive while others do not.•Sources of inherited variation: meiosis, crossing over, mutation.•Allele frequency change is called evolution. Sometimes it causes speciation.Charles Darwin•Age 25: set sail on 5 year voyage on HMS Beagle as “naturalist”.A reconstruction of the HMS Beagle sailing off Patagonia.Darwin’s Voyage of DiscoveryThe Voyage of the BeagleCape Verde and Galapagos ArchipelegosGalapagos Islands and South American MainlandIntra-Galapagos Variability:Darwin’s FinchesDarwin saw patterns among a diverse, extensive array of fossils & specimens(worked on it for a couple decades!) Charles Darwin observed animals and plants in the Caribbean, South America, the Galapagos, Hawaii, Indonesia, Africa and