Evolution - Evolution Basic Principles and Supporting Evidence Supporting Evolutio Evolutio n The scientific theory that populations The change in

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Unformatted text preview: Evolution: Basic Principles and Supporting Evidence Supporting Evolutio Evolutio n The scientific theory that populations The change in their genetic compositions over a number of generations. over Evolutio Evolutio n The scientific theory that all extant The species, including human beings, have descended from different prehave existing species through a natural existing process of change, and that related species (ultimately probably all species) share a common ancestor. species) Microevolution Versus Macroevolution Macroevolution Evolutio Evolutio n No characteristic of the genetic No instruction set, nor any known mechanism for inheritance, nor any fundamental property of the living world, prohibits microevolution from becoming macroevolution. becoming Mechanisms of Evolutionary Change Evolutionary Genetic Change Chance Events Natural Selection Charles Darwin Darwin The HMS Beagle Beagle Voyage of the HMS Beagle Beagle The Galapagos Islands Islands The Galapagos Islands Islands Giant Tortoises Giant Marine Iguanas Marine Land Iguanas Iguanas Mockingbir Mockingbir ds Finche Finche s Darwin’s Five Theories of Evolution Evolution 1. Perpetual Change 2. Common Descent 3. Multiplication of Species 4. Gradualism 5. Natural Selection Perpetual Change Change The universe is neither constant, nor recently created, nor perpetually cycling, but is steadily changing and and its kinds of living things are transformed in time. Fossil Fossil s Common Descent Descent Every group of organisms (e.g., vertebrates) have descended from a common ancestor; and all groups of organisms, including animals, plants, and microorganisms, ultimately go back to a single origin of life on earth. Common Descent Descent Common Descent Descent Homologous Structures Homologous Human Cat Whale Bat Embryonic Development Fis h Bird Reptile Huma Biology 100 Biology Human Biology Biology 100 Biology Human Biology Biology 100 Biology Human Biology Biology 100 Biology Human Biology Biology 100 Biology Human Biology Vestigial Structures Structures Whale Embryo Whale hind limb bud Genetic Relatedness Genetic Multiplication of Species Species Species multiply either by splitting or Species “budding” into daughter species, that is by establishment of geographically isolated founder populations that evolve into new species. evolve Allopatric Speciation Allopatric Allopatric Speciation Allopatric Allopatric Speciation Allopatric Allopatric Speciation Allopatric Allopatric Speciation Allopatric Finche Finche s Gradualism Gradualism Evolutionary change takes place Evolutionary through the gradual change of populations and not by the sudden (saltational) production of new individuals that represent a new species. species. Gradualis Gradualis m Gradualis Gradualis m Punctuated Equilibrium Punctuated Punctuate Punctuate d Equilibriu Equilibriu m Gradual Evolution Evolution Natural Selection Natural Evolutionary change comes about Evolutionary through the abundant production of genetic variation in every generation. The relatively few individuals who survive, owing to well-adapted combinations of heritable characters, give rise to the next generation. give Natural Selection Selection Observation 1 Living things generally produce Living more offspring than are necessary merely to replace the parents. merely Natural Selection Selection Observation 2 Natural populations tend to remain Natural constant in size. constant Natural Selection Selection Conclusion 1 Not all individuals survive; or they Not fail to reproduce. fail Natural Selection Selection Observation 3 Within a population, individuals Within exhibit variation in their characteristics; that is, no two individuals are exactly alike. individuals Natural Selection Selection Observation 4 Much of this variation is heritable. Natural Selection Selection Conclusion 2 Some organisms exhibit heritable Some characteristics that make them more likely to survive and produce offspring. offspring. Natural Selection Selection Conclusion 3 Those individuals with the most Those favorable (adaptive) characteristics will contribute greater numbers of offspring with the same favorable characteristics to the succeeding generation. generation. Natural Selection Selection Conclusion 4 Thus, over time (from one Thus, generation to the next), the population changes in its genetic composition. composition. Natural Selection Selection Conclusion 5 Through the accumulation of Through genetic change over many generations, a species may change substantially, being transformed into a new species. transformed Lamark Lamark Directional Selection Kettlewell (1950’s) investigated color variation in peppered moths. Questions: 1. Why had this color variation taken place in the moth population? 2. Why were dark gray moths more common only in industrial areas while light gray moths were still predominant in rural areas? 3. What do these observations mean? The frequency of color varieties changes dramatically in one direction or another (lighter or darker) in response to the predominating habitat conditions. Some Other Examples of Natural Selection Selection • Beak Depth in Galapagos Finches • Pesticide Resistance in Insect Pesticide Pests Pests • Antibiotic Resistance by Bacteria • Sickle Cell Anemia in Humans ...
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This note was uploaded on 04/19/2011 for the course BIOL 101 taught by Professor Wong during the Fall '09 term at University of Hawaii, Manoa.

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