EEMB 102 – Lecture 2Who is going to/*should* be the 2016 World Series Champion?From Last TimeFrom Last Time: DarwinismToday: What is microevolution? (overview, review)Modern SynthesisHardy-Weinberg EquilibriumEffects of Gene FlowLarger Context: Do the microevolutionary processes of mutation, selection, gene flow, and drift explain all the patterns of macroevolution?II. Testing the Postulates of Natural Selection Demonstrating natural selection in the wildPowerPoint PresentationSlide 12Beak size/shape related to dietSlide 14Galapagos IslandsDaphne Major, GalapagosWhich of the following must be present to demonstrate natural selection?Four Postulates of Natural SelectionNatural Selection – Postulate 1Measure individualsVariation in Beak DepthNatural Selection – Postulate 2Correlation between parent’s and offspring’s bill depthNatural Selection – Postulate 3Identify individuals (banding)Many Offspring Don’t ReproduceExamples from other speciesCorrelation – Lower Population Size and Lower Seed SupplyNatural Selection – Postulate 4Harder Seeds and Larger BeaksSurvival of Non-Random SubsetCould these finch experiments have been done in Darwin’s day?Slide 33HHMI VideoIII. Common Misunderstandings of Natural SelectionChemostatIn a chemostat (constant environment with unlimited ‘food’), evolution WILL occur.Growth Rate Increases In ChemostatIn the finch population, what are the primary changes that occur gradually over time?Selection acts on individuals, Consequences occur in populationsB. Selection acts on phenotypes but microevolution is change in gene frequenciesHow did different beak types first arise in various Darwin’s finches?C. Natural Selection is NOT forward-lookingD. Natural Selection Acts on Existing TraitsE. Natural Selection is not “Random”Which Lizard (A,B,C,D) has highest evolutionary fitness?F. Fitness is not circularEEMB 102 – Lecture 2Review/Overview of Microevolutionary ProcessesWho is going to/*should* be the 2016 World Series Champion?•A) Los Angeles Dodgers•B) San Francisco Giants•C) Chicago Cubs•D) Los Angeles Angels of Anaheim•E) None of the above (Jays, Nats, D’Backs maybe?)m.socrative.com room=eemb102From Last Time•Is Evolution still Darwinian (Gould’s book)?•Can microevolution alone explain macroevolution?From Last Time: Darwinism•Ernst Mayr’s Darwinism is:–Evolution as such –Common descent–Multiplication of species –Gradualism–Natural selectionToday: What is microevolution? (overview, review)•I. The Modern Synthesis•II. Natural Selection – Textbook Galapagos Finch example•III. Common Misunderstandings of SelectionModern Synthesis•Combination of Genetics with Darwin’s evolution theories•Mainly focused on microevolution•Expanded with mathematical formulations of population genetics–Sewell Wright–R.A. Fisher–J.B.S. HaldaneHardy-Weinberg Equilibrium•Powerful as a NULL MODEL for microevolution•Deviations from a null model mean simple assumptions are not met•HW assumes no evolution•Deviations from HW one or more assumption is not met–Natural selection–Gene Flow–Genetic DriftEffects of Gene Flow–Populations exchanging alleles (through reproduction) are more similar (overall, the species is more Homogeneous)–Isolated populations accrue differences (Overall, the species is more Heterogeneous)Larger Context:Do the microevolutionary processes of mutation, selection, gene flow, and drift explain all the patterns of macroevolution?II. Testing the Postulates of Natural SelectionDemonstrating natural selection in the wildGalapagosFinchesBeak size/shape related to dietGalapagos IslandsDaphne Major, Galapagos‘ “If I have seen farther”, Isaac Newton once wrote, with celebrated modesty, “it is by standing upon the shoulders of giants.” The dark volcanoes of the Galapagos are Darwin’s shoulders.’Jonathan Weiner, The Beak of the FinchWhich of the following must be present to demonstrate natural selection?•A) Individuals vary•B) Some variation is heritable•C) Not all individuals survive•D) Differential fitness•E) All of thesem.socrative.com room=eemb102Four Postulates of Natural Selection•Individuals vary•Some variation is heritable•Not all individuals survive•Differential fitnessNatural Selection – Postulate 1•Populations harbor variation•How can we test this postulate?Measure individualsVariation in Beak DepthBeak Depth (mm)Beak Depth% of total birds108 12Natural Selection – Postulate 2•Some of the variation among individuals is heritable•How can we test this postulate?Correlation between parent’s and offspring’s bill depthBoag (1983) EvolutionNatural Selection – Postulate 3•Not all individuals survive to reproduce •How can we test this postulate?Identify individuals (banding)Many Offspring Don’t Reproduce•89% of G. conirostris die before breeding (Rosemary Grant, 1985 Evolution)•In 1977 84% of the population on Daphne Major disappeared (Boag & Grant 1981)•19% and 25% gone in 1980 and 1982 (Price et al 1984)Examples from other species•Elephants – 19 million after 75 years from one original pair (Darwin, 1859)•1079 starfish in 16 years from one original pair = estimated # of electrons in the universe (Dodson, 1960)Correlation – Lower Population Size and Lower Seed SupplyNumber of BirdsNumber of SeedsNatural Selection – Postulate 4•Survival is non-random with respect to trait(s)•How can we test this postulate?Harder Seeds and Larger BeaksSurvival of Non-Random Subset•Average beak depth changed after drought•AFTER drought (9.7 +/- 0.06)•BEFORE drought (9.21 +/- 0.02)Could these finch experiments have been done in Darwin’s day?Daphne Major, Galapagos‘In the distant future I see open fields for far more important researches”, Darwin writes in the last pages of the Origin. “Light will be thrown on the origin of man and his history”. The study of evolution in action throws light on our origin and our history… It also casts a new light on our tumultuous present and our destiny: for the processes that are illuminated by these studies, the processes that got us here, are in turmoil. With the conditions of life on this planet changing everywhere faster and faster, the pressures of natural selection are everywhere, increasing in intensity, daily and hourly, even on islands as remote as the Galapagos. Whether or not we choose to watch, evolution is shaping us all. ’Jonathan Weiner, The