* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download EVOLUTION - Carol Eunmi LEE - University of Wisconsin–Madison
Survey
Document related concepts
Unilineal evolution wikipedia , lookup
Sexual selection wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
On the Origin of Species wikipedia , lookup
Natural selection wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Population genetics wikipedia , lookup
Theistic evolution wikipedia , lookup
The Expression of the Emotions in Man and Animals wikipedia , lookup
Transcript
History of Evolutionary Thought Dr. Carol Eunmi Lee University of Wisconsin, Madison Today’s OUTLINE: (1) Development of Darwin’s Thought (2) Lamarck vs. Darwin (3) The Contribution of Darwin (4) The Contribution of Mendel (5) Conflict between “Mendelism” and “Darwinism” (6) The “Evolutionary Synthesis” of Mendel and Darwin Key Points: (1) What exactly were the components of Darwin’s theory of Evolution, and what was missing? (2) What exactly did Mendel contribute? (3) What is the difference between Lamarck vs. Darwin’s ideas, and how does Lamarck’s ideas contribute today? Charles Darwin (1809-1882) Origin of Species is one of the most influential texts of this century Charles Darwin (1809-1882) His father was a doctor (Richard Darwin) and his grandfather was Erasmus Darwin, also a doctor and a prominent scholar who was already thinking about evolution Initially he studied Medicine at the University of Edinburgh He neglected his studies and could not stand the sight of surgery or the sight of blood (had nausea, fainted) Sent by his father at Christ’s College, Cambridge University to become an Anglican priest He still neglected his studies, but he did pursue a passionate interest in Natural History He became close to botany professor Rev. John Henslow and met other leading naturalists who saw scientific work as religious natural theology (and viewed adaptation [i.e. evolution] as God acting through laws of nature) Reverend John Stevens Henslow (1796–1861) “I fully believe a better man never walked this earth” Charles Darwin to J.D. Hooker, 1861 Darwin’s Botany professor at Christ’s College (Divinity School), Cambridge University Henslow encouraged students to make observations of their own, rather than being spoon-fed After Darwin completed his final examination in 1831, Henslow persuaded him to begin studying geology, and made arrangements for him to take Adam Sedgwick’s geology course and a trip to map geological strata in North Wales Shortly thereafter, in 1831, Henslow encouraged Darwin to join the Voyage of the Beagle as the ship’s naturalist More on Henslow: Darwin's Mentor: John Stevens Henslow 1796–1861 By Walters & Stow Voyage of the Beagle HMS Beagle, a ship sent by British Navy to chart coastline of South America HMS Beagle off of South America During the 5-year Voyage Darwin was supposed to be primarily a geologist; He had some expertise in geology, beetle collecting and dissecting marine invertebrates He made observations on geological formations as the ship was mapping the coastline At Punta Alta in Patagonia he made a major find of fossil bones of huge extinct mammals in cliffs beside modern seashells, indicating recent extinction with no signs of change in climate or catastrophe (“extinctions happen”) The Galapagos Islands Archipelago of volcanic islands distributed around the equator in the Pacific Ocean, 972 km (525 nmi) west of continental Ecuador The Galapagos Islands Why were these islands so important in shaping Darwin’s thinking? The Galapagos Islands • As an archipelago, there were many islands with different populations of a “species” on each island • The populations were related, but were slightly different on each island… (not clear boundaries) • This led Darwin to conclude that the populations descended from a common ancestor… and he ultimately concluded that they had evolved and were evolving… • led Darwin to question the stability of the concept of a “species” Darwin’s Mockingbirds "My attention was first thoroughly aroused by comparing together the various specimens ... of the mocking-thrush" C. Darwin, The Voyage of the Beagle (1839) • On Sept 17 1835, Darwin disembarked from the Beagle in the Galápagos near Sappho Cove on Chatham Island (now known as Isla San Cristóbal), and was struck by the bold, terrestrial mockingbird. • The bird is known today as Mimus melanotis, the San Cristóbal Mockingbird. Over the next 6 weeks that Darwin spent in the Galápagos, he observed mockingbirds on three other islands. • Darwin noticed the mockingbirds differed between islands. Nicolas Lawson, acting Governor of Galápagos, told Darwin that the tortoises also differed from island to island. • Towards the end of the voyage, Darwin speculated that the distribution of the mockingbirds and the tortoises might "undermine the stability of Species”. Species might not be fixed entities, but are changing over time… Galapagos Islands Darwin’s Mockingbirds (he did not focus that much on the finches; they were studied more later by the Grants) Tortoises and other animals Mockingbirds on different islands differed slightly in size, shape and coloration And all shared some traits (homologous traits) He concluded that these birds must have shared a common ancestor--and were not independently created Mockingbirds on different islands differed slightly in size, shape and coloration (species not immutable discrete entities) And all shared some traits (homologous traits) He concluded that these birds must have shared a common ancestor--and were not independently created Branching, Tree-like thinking (rather than ladder) Significance of the HMS Beagle Voyage • Collections to study later • Exposed Darwin to geological formations, fossils embedded in strata – animals that no longer exist today and are clearly extinct – this was known, but Darwin got to see this himself • Exposure to animal diversity, related populations within species living in different habitats: 1. “Species” are not immutable fixed entities 2. Organisms are related by common ancestry (tree-like branching) 3. They are changing and branching in response to the environment Return to England Returned and discussed his geological and biological finding with other scholars, influenced by Malthus, etc. Married the wealthy Emma Wedgewood Did not have to work, and could study the samples he collected, perform experiments, make observations, think, and write books for the rest of his life Historical Context: By mid-1800s scientific context was in place for development of theory of Evolution Developments in Geology: Discovery that earth is more than 6,000 years old Fossil Record showed change in species over time http://www.ucmp.berkeley.edu/history/evotmline.html Influences on Darwin Geology: Darwin had Lyell’s Principles of Geology on board the HMS Beagle Lamarck ’s (1744-1829): Concept of Adaptation, Inheritance of acquired characteristics Malthus (1766-1834): Competition within species and struggle for survival Influences on Darwin Geology: Darwin had Lyell’s Principles of Geology on board the HMS Beagle, given to him by captain of the HMS Beagle (Robert FitzRoy) Fossil record: The earth is old Many animals that once existed are now extinct There are layers (strata) in the fossil record show a pattern of change the idea that species change over time and that some go extinct Jean-Baptiste Lamarck French Naturalist (1744-1829) “Professor of Worms and Insects” in Paris The first scientific theory of evolution (inheritance of acquired characteristics) Influences on Darwin Lamarck ’s (1744-1829) theory of Evolution Inheritance of acquired characteristics Proposed the most influential mechanism of evolution before Darwin: Introduced the idea of Adaptation, though he was mostly incorrect on the predominant mechanism (though sometimes correct; will discuss Epigenetic Inheritance) Influences on Darwin Thomas Malthus (1766-1834): “Essay on the Principle of Population” Population The idea of competition: food Malthus’ calculations showed that rate of population growth was greater than rate of increase in food supply Thus, not all individuals could possibly survive Based on this fact of competition, Darwin concluded that individuals that are better adapted would be the ones that survive and leave more offspring (and win the competition) Malthus From Malthus, Darwin came up with the idea of competition and the “struggle for survival” as a component of Natural Selection With these influences on this thought and data from the Galapagos Islands… Darwin developed the theory of Evolution via Natural Selection… The scientific community was primed for a theory of Evolution Darwin was one of many scholars at his time that were thinking about Evolution Many scholars accepted the idea of Evolution at the time… what puzzled them was the mechanism In fact, Alfred Wallace (1823-1913) came up with the idea of natural selection independently Darwin rushed to publish Origins in 1859 when he learned of Wallace’s work Alfred Russel Wallace (1823-1913) “On the Tendency of Varieties to Depart Indefinitely from the Original Type” Based on his work in the Malay Archipelago He also studied populations on different islands and came to the same conclusion as Darwin Alfred Russel Wallace (1823-1913) Father of Biogeography… focused on adaptation to the environment In 1858 Wallace sent Darwin a copy of his manuscript Darwin was shocked that Wallace came up with the idea of natural selection independently They decided on a joint presentation at the Linnean Society in 1858, but it received little attention After which Darwin rushed to publish his book in 1859 Charles Darwin (1809 -1882) On the Origin of Species (1859) Living species are related by common ancestry Change through time occurs at the population not the organism level The main cause of adaptive evolution is natural selection Darwin’s Main Points: (1) Organisms Evolve (Darwin not first) (2) Common Descent: species arise from common ancestors, in a tree-like branching process (Wallace also) (3) Gradualism: changes are gradual (we now know that this is not always true) (4) Population Speciation: change in proportions of individuals having a trait in a population (Darwin’s original idea) (Wallace also) (5) Natural Selection: is the mechanism (Wallace also) So… Darwin did NOT originate the idea of Evolution… … BUT he provided a plausible Mechanism (along with Wallace) … and much evidence Lamarck vs Darwin Before Darwin had developed his ideas on the mechanism of evolution, Lamarck had proposed an alternate mechanism that was popular at the time Lamarck vs Darwin (1) Different View on pattern of Evolution Lamarck: Linear progression Darwin: Tree-like branching process (2) Different View on Mechanism of Evolution Lamarck: inheritance of acquired traits (not mutations)-Individual evolution Darwin: Evolution at the Population Level via Natural Selection Lamarck’s View on Pattern of Evolution Continuum between physical and biological world (followed Aristotle) Being Realm of Being Scala Naturae (“Ladder of Life” or “Great Chain of Being”) “Transmutation of Species” –one species turns into another Linear progression from primitive to advanced God Angels Demons Man Animals Realm of Becoming Plants Minerals Non-Being What is wrong with a ladder? Evolution is not linear but branching Living organisms are not ancestors of one another The ladder implies progress Darwin envisaged Evolution as a Tree The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth…… …The green and budding twigs may represent existing species; and those produced during former years may represent the long succession of extinct species….. ….the great Tree of Life….covers the earth with ever-branching and beautiful ramifications Charles Darwin, On the Origin of Species; pages 131-132 The only figure in Origin of Species Lamarck’s View on Mechanism of Evolution Individuals are evolving If you got a tan, you’d pass it on Lamarck’s View on Mechanism of Evolution Individuals are evolving If you got a tan, you’d pass it on Some balls get tan during their lifetime Lamarck’s View on Mechanism of Evolution Individuals are evolving If you got a tan, you’d pass it on Tan balls pass on their acquired trait to their offspring (We now know that acquired traits could get passed on sometimes when epigenetic modifications are inherited) Darwin’s View on Mechanism of Evolution Natural Selection A heritable difference (now known to be due to different mutations) Darwin’s View on Mechanism of Evolution Natural Selection Selection might favor this mutation Darwin’s View on Mechanism of Evolution Natural Selection Greater Fitness: individuals with this mutation survive and leave more offspring Darwin’s View on Mechanism of Evolution Natural Selection The individuals themselves are not changing, but the population is changing in composition (% of alleles) Darwin’s contribution: “Population Speciation as a result of Natural Selection” More offspring are produced than can survive Limited resources and competition for resources (“The Struggle for Survival”) There is variation in a population Individuals better adapted to environment survive Survivors leave more offspring (“Survival of the Fittest”) Thus, average character of population is altered But… Darwin’s theory was not complete Because Darwin knew nothing about mutation, he had no idea how variation was generated in populations Because Darwin knew nothing about genetics or genes, he had no idea how variation was passed on to offspring (Mendel & Hardy-Weinberg) Darwin did not know about nonadaptive evolutionary forces, such as Genetic Drift Sample Exam Question Which of the following was NOT part of Darwin’s theory of Evolution? (1) Natural Selection (2) Populations as the units of Evolution (3) Mutations as sources of genetic variation (4) Survival of those who produce more offspring Mendel’s work held part of the key to what was missing in Darwin’s Theory Mendel published in 1865… was ignored until 1900 Presented a mechanism for how traits got passed on “Individuals pass alleles on to their offspring intact” (the idea of particulate (genes) inheritance) Hardy-Weinburg Equilibrium (Lecture 3) Wilhem Weinberg January 13, 1908 G. H. Hardy July 10, 1908 in Science The Mathematical expression of Mendel’s Principles of Inheritance Hardy-Weinburg Equilibrium (Lecture 3) Wilhem Weinberg G. H. Hardy January 13, 1908 July 10, 1908 in Science Could mathematically show expectations of Mendelian inheritance and whether expectations are realized in nature PROBLEMS! BUT… Mendel and Darwin’s ideas seemed Incompatible Mendel’s principles: dealt with particulate (discrete) traits (e.g. yellow vs. green, wrinkled vs. smooth) BUT, Darwin observed continuous traits (e.g. beak size, body length) Q: So, how would continuous traits get passed on? Selection vs Mutations Mutations discovered after 1900 Q: If mutations are arising, why need selection... … if things are just mutating? Controversy between Mutationists vs Darwinists Mutationists (+Mendelianism) They thought that evolution required only mutations and passing on of discrete traits Darwinists They thought that evolution required only Natural Selection on continuous variation Discrete vs Quantitative Traits Darwin was unable to clearly see the pattern of inheritance because he studied quantitative variation • Discrete trait: a trait that has distinct values, rather than a range of phenotypes, usually encoded by one or a few genes. Frequency Examples: number of fingers, color of Mendel’s peas, sickle cell anemia, ABO blood type, number of eggs in a bird clutch, presence/absence of human widow’s peak, presence/absence of dimples, etc. • Quantitative (continuous) trait: a trait that has a continuum of phenotypes and is encoded by multiple genes. Examples: body size, height, weight, intelligence (IQ), Running speed, beak shape, hair color, skin color, milk yield of cows, lifespan, etc. Type Frequency Type Controversy between Mutationists vs Darwinists Controversy persisted for ~30 years up till the 1930s, during which little progress was made Problem caused by: Binary thinking (Black or White thinking): it’s this or that… “if I’m right, you must be wrong” When in fact the two or more factors might interact Inability to see overarching mechanism that could explain a wide range of phenomena: “How could your Hardy-Weinberg (Mendel) explain the inheritance of 5.1 cm, 5.5 cm beak length (continuous characters)?” When in fact, another factor might make it possible (think multiple genes, rather than one gene) Genetic Drift (Lecture 5) A concept as important as Natural Selection But, not as prominent on people’s minds 1872 Gulick: Neutral Theory (Genetic Drift) 1921 A.C. Hagedoorn produced data to support Neutral Theory of Genetic Drift The Modern Synthesis 1930s ~ 1940s The synthesis of population genetics (role of mutation, genetic drift), paleontology, systematics Darwin and Mendel Reconciled!!! (Next Lecture) The Modern Synthesis 1930s ~ 1940s Also called the “Synthesis of Evolution and Genetics” Among the Greatest Scientific Revolutions of the Century Three of the "architects" of the evolutionary synthesis: G. Ledyard Stebbins, Jr., George Gaylord Simpson, Theodosius Dobzhansky Photograph from Smocovitis, V. B. 1997. G. Ledyard Stebbins, Jr. and the evolutionary synthesis (1924-1950). American Journal of Botany 84: 1625-1637. The Evolutionary Synthesis was important because many scientists from different fields convened to discuss the evolutionary mechanisms and clear up confusion and inconsistencies Some Key Tenets of the Modern Synthesis Populations are the units of Evolution Mendel vs Darwin: continuous traits are also coded by particulate genes, but many genes Mutation vs Selection: Mutations are sources of genetic variation upon which Selection acts Natural Selection and Mutation are not the only evolutionary forces. Examples: Genetic Drift, Recombination Microevolutionary processes, such as Drift, Selection, Mutation, lead to Macroevolutionary changes (such as speciation) Some Tenets of the Evolutionary Synthesis The phenotype is different from the genotype Acquired characters (phenotypic plasticity) are not inherited Traits are inherited via genes, and they do not “blend” with other genes (Darwin was wrong about this one) Genes mutate, resulting in different alleles Evolution occurs at the population level, due to a change in proportions of individuals with different genotypes Changes in proportion in a population could occur via random genetic drift (Sewall Wright) or Natural Selection… the rate of mutation is usually too low to cause large changes in proportions Even very weak natural selection could cause substantial changes over a longer time scale Mutations generate the genetic variation upon which natural selection acts Microevolutionary processes lead to Macroevolutionary changes (speciation) All organisms on the planet are related to one another in a great “tree of life”, and have diverged by branching from common ancestors Gaps in the fossil record are likely due to incompleteness of the fossil record. Gradual changes seen in many parts of the fossil record suggest gradual changes over time Mutation vs Selection and Reconciling Mendel and Darwin Mutation vs Selection And Reconciling Mendel and Darwin continuous and discrete traits could follow the same principles of inheritance (Mendel), just that continuous traits are coded by many genes (loci) If there are many genes (loci) coding for a trait, rather than one, the offspring look intermediate between the parents (looks like “blending inheritance”) BUT, the SAME Mendelian patterns of inheritance apply, it’s just that you don’t see the particulate inheritance of each gene in the offspring, but the average effect across all the genes affecting the trait How do you deal with quantitative traits? (2nd point below) Hardy Weinberg: multiple alleles: 3 alleles: (p + q + r)2 which expands to... p2 + 2pq + q2 + 2pr + 2qr + r2 =1.0 4 alleles: (p + q + r + s)2 Hardy Weinberg: multiple loci HW principle still applies to each locus independently Need to use principles of Quantitative Genetics to examine effects of multiple loci The Population Geneticists JBS Haldane Sewall Wright Mathematical theory of population genetics showed that mutation and selection TOGETHER cause adaptive evolution: RA Fisher Mutation is NOT an alternative to Natural Selection, but the raw material upon which natural selection acts. Fisher vs Wright Both appreciated the importance of Natural Selection AND Genetic Drift But they argued about the relative importance Ronald Aylmer Fisher (1890-1962) Background in math, physics, astronomy, and genetics Made key contributions to the field of Statistics Ronald Aylmer Fisher (1890-1962) • Natural selection occurs in large populations • Many genes are involved • Mutations are the main substrate for selection Other Contributions: • Adding mathematical rigor into the theory of selection • Elegant synthesis of Mendelian inheritance into the Theory of Selection • Important developments in Statistics (ANOVA) Sewall Wright (1889-1988) Heavily influenced by examples from agriculture Worked for the US Dept of Agriculture: breeding in guinea pigs and cattle Became a professor at UW-Madison in Genetics Sewall Wright (1889-1988) • Inbreeding and Genetic Drift are important for creating new gene interactions • These new gene interactions (epistasis caused by new recombinations) are the main substrate for selection The Population Geneticists If you want to read more about this topic, this book is a good read Reconciling Microevolutionary Mechanisms and Macroevolutionary processes Microevolution Macroevolution Ernst Mayr George Gaylord Simpson G. Ledyard Stebbins Bernhard Rensch and others Ernst Mayr George Gaylord Simpson Microevolutionary processes within species account for macroevolution among species (Lecture #18) That is, mutation, recombination, natural selection, and other processes that act within species (microevolution) are the SAME mechanisms that account for the origin of new species and major long term evolution (macroevolution) (Lecture #18) James F. Crow (1916-2012) University of Wisconsin, Madison His work has touched on nearly every area of evolutionary genetics -will discuss some of his contributions in Lecture #7 http://www.genetics.wisc.edu/CATG/crow/index.html Moral of the Story Scientists from different fields should talk to each other Should avoid binary thinking (this vs that, right vs wrong), as different mechanisms might work together in an integrated fashion We are often biased by what we study (example of continuous vs discrete traits) After the Evolutionary Synthesis The Importance of Natural Selection vs Genetic Drift Ongoing debate after the Evolutionary Synthesis Even after the synthesis the relative importance of Natural Selection and Genetic Drift was debated • During the Evolutionary Synthesis, Sewall Wright focused more on importance of Genetic Drift, whereas Fisher focused on Natural Selection • Shortly after the Evolutionary Synthesis many focused on selection to the point of assuming that most phenotypes were the result of Natural Selection • Emphasis on Genetic Drift resurged in the 1970s, 80s with Kimura’s “Neutral Theory” • Then in the 2000s and 2010s interest in Selection increased with the ability to detect signatures of Natural Selection in genome sequence data Motoo Kimura (1924-1994) The Neutral Theory of Molecular Evolution Classic Paper: Kimura, Motoo. 1968. Evolutionary rate at the molecular level. Nature. 217: 624–626. Classic Book: Kimura, Motoo (1983). The neutral theory of molecular evolution. Cambridge University Press. The Neutral Theory of Molecular Evolution (Lecture #6) • The Neutral theory posits that the vast majority of evolutionary change at the molecular level is caused by random genetic drift rather than natural selection. Motoo Kimura • Neutral theory is not incompatible with Darwin's theory of evolution by natural selection: adaptive changes are acknowledged as present and important, but hypothesized to be a small minority evolutionary change. • Recent tests of selection have found that in many cases evolution is not neutral, even in non-coding regions of the genome. • Nevertheless, the neutral theory is useful as a null hypothesis, against which selection could be tested. While the Evolutionary Synthesis was a HUGE leap in the right direction, there were a few tenets that required modification (as a result of new discoveries in Genetics) Some Tenets of the Evolutionary Synthesis The phenotype is different from the genotype Acquired characters (phenotypic plasticity) are not inherited –not always true Traits are inherited via genes, and they do not “blend” with other genes (Darwin was wrong about this one) Genes mutate, resulting in different alleles Evolution occurs at the population level, due to a change in proportions of individuals with different genotypes Changes in proportion in a population could occur via random genetic drift (Sewall Wright) or Natural Selection… the rate of mutation is usually too low to cause large changes in proportions Even very weak natural selection could cause substantial changes over a longer time scale Mutations generate the genetic variation upon which natural selection acts Microevolutionary processes lead to Macroevolutionary changes (speciation) All organisms on the planet are related to one another in a great “tree of life”, and have diverged by branching from common ancestors Gaps in the fossil record are likely due to incompleteness of the fossil record. Gradual changes seen in many parts of the fossil record suggest gradual changes over time –not always true Completing the Synthesis Advances in Genetics Epigenetic Inheritance (Lecture #9) Some genetic changes could lead to radical changes in phenotype (Lecture #7) Polyploidization seen often in plants Changes in developmental genes Regulatory Evolution Transposons Evolution at the Molecular Genetic Level Which types of mutations predominate and contribute to adaptations more often? Structural vs Regulatory? Is phenotypic evolution occurring predominantly at the level of gene products (e.g. proteins) or at the level of gene regulation (e.g. transcription, RNA processing, translation, etc.)? cis-Regulation vs trans-Regulation? Is regulatory evolution occurring predominantly at the level of cis-regulatory elements (e.g. promoter, enhancers) or at the level of trans-acting factors (e.g. transcription factors, etc.)? More on Lectures on Molecular Evolution (Lecture #13) The role of Epigenetics (Lecture #9) Lamarck Revisited Lamarck was incorrect in thinking that the inheritance of acquired characters is the main mechanism of evolution However, we do now know that the inheritance of acquired characters does happen sometimes, through the inheritance of epigenetic modifications Evolution of Development (Lecture #26) How small changes in developmental genes (like Hox genes) could radically cause the evolution of body plans Will talk more about this when I get to lecture on Animal Diversity Role of Genomics (Lectures #15, 16) How does the whole genome evolve? How does selection act on networks of interacting genes? How many and which genes are involved in the formation of new species? Today: Genome Evolution and Systems Biology How do multiple genes interact? How do multiple genes affect a phenotype? Systems Biology: How does selection act on interacting gene networks? Evolution of Genome Architecture Questions: (1) What were the intellectual influences on Darwin’s thought? (2) What role did the discoveries from the Beagle’s voyage play in the development of Darwin’s thought? (3) What were Darwin’s main conclusions? (4) How did Darwin’s thought differ from that of Lamarck? (4) What did Darwin’s theory leave out? (5) What was Mendel’s contribution? (6) What were the sources of confusion between the proponents of Darwin and Mendel’s ideas? Questions: (1) What were the sources of confusion regarding evolutionary mechanisms prior to the Evolutionary Synthesis? (2) What was the Modern (Evolutionary) Synthesis? (3) What were the main tenets of the Evolutionary Synthesis? (4) What is the relationship between natural selection, genetic drift, mutations, and recombination? (5) What were some of the limitations of the Evolutionary Synthesis? (6) What were some key developments since the Evolutionary Synthesis? (7) What gaps remain in our understanding today? CONCEPTS Evolution Population Natural Selection Evolutionary Adaptation Fitness Mutation Genetic Drift Recombination Hardy-Weinberg Equilibrium Development of Darwin’s thought Lamarck vs Darwin Darwinists vs Mendelists Evolutionary Synthesis Sample Exam Questions 1.Which of the following is TRUE regarding Darwin’s contribution to the theory of Evolution? (A) Darwin formulated the first comprehensive theory incorporating all mechanisms of evolution (B) Darwin recognized that evolution occurs at the population level (in terms of changes in frequency of traits within populations) (C) Darwin proposed that selection acts on mutations and other forms of genetic variation (D) Darwin agreed with Larmarck’s idea of inheritance of acquired characters, but included the concept of fitness. (E) Darwin incorporated Mendel’s work on the particulate inheritance of alleles 2. For several decades "Darwinists" and "Mendelists" battled over the mechanisms of evolution. Which of the following did NOT contribute to this particular conflict? (a) Geneticists/Evolutionary biologists did not understand that continuous and discrete traits follow the same principle of inheritance (b) Geneticists/Evolutionary biologists did not understand that natural selection acts on mutations in a population (c) Mendel worked with discrete traits, whereas Darwin worked with continuous traits, leading to differences in perspectives on inheritance (d) Darwin was unaware of the mechanism or unit of inheritance (e) Darwin was unaware of the mechanisms of Genetic Drift 3. Darwin’s development of the theory of evolution by natural selection was NOT influenced by which of the following? (a) The concept of adaptation to the environment, which was proposed by Lamarck (b) Fossils of extinct organisms (c) Each island of an archipelago having a population with morphological differences from those on other islands (d) Malthus' demography showing exponential growth of populations (e) Changes in frequency of discrete characters from generation to generation Sample Exam Question Which of the following was NOT a tenet of the Evolutionary Synthesis? (a) Evolution occurs at the level of populations, in terms of changes in allele frequencies, rather than changes at the individual level (b) Selection could act on traits that are coded by multiple genes (c) Selection acts on genetic variation in traits that are caused by mutations (d) Natural Selection and Mutation are the only causes of evolutionary change (e) Microevolutionary processes within populations lead to Macroevolutionary changes among populations Answer: d Additional Optional Slides (for your interest) Chapters of Origins (1859) On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life 1 Variation Under Domestication 2 Variation Under Nature 3 Struggle for Existence 4 Natural Selection 5 Laws of Variation 6 Difficulties on Theory 7 Instinct 8 Hybridism 9 On the Imperfection of the Geological Record 10 On the Geological Succession of Organic Beings 11 Geographical Distribution 12 Geographical Distribution continued 13 Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs 14 Recapitulation and Conclusion Other books by Darwin on Evolution The Variation of Plants and Animals under Domestication The Descent of Man The Expression of the Emotions of Man and Animals Full list of books by Darwin: http://en.wikipedia.org/wiki/Charles_Darwin_bibliography Charles Darwin's 1837 sketch, his first diagram of an evolutionary tree from his First Notebook on Transmutation of Species (1837) on view at the the Museum of Natural History in Manhattan. Interpretation of handwriting: "I think case must be that one generation should have as many living as now. To do this and to have as many species in same genus (as is) requires extinction . Thus between A + B the immense gap of relation. C + B the finest gradation. B+D rather greater distinction. Thus genera would be formed. Bearing relation" (next page begins) "to ancient types with several extinct forms"