Transcript Evolution
Evolution MRS. BARROW Learning Objectives 1.25 Student is able to describe a model that represents evolution with in a population 1.26 Student is able to evaluate given data sets that illustrate evolution as an ongoing process Prior Beliefs Aristotle (384-322 BC) : Time allowed more complex life- forms to develop Theology : Old testament, Divine Creation Taxonomy ( Linnaeus 1707-1778) : Blended complexity with creationism (intelligent design) Gradualism (Hutton 1726-1796) : Changes took place slowly Lamarck (1744-1829) : Use and disuse, acquired characteristics Catastrophism (Cuvier 1769- 1832) : Destruction of organisms and evolution of replacements Uniformitarianism (Lyell 1797- 1875) : Same process as in the past Hutton Vs. Lyell Lamarckian Vs. Darwinian Evolution Darwinian evolution posits organism genetic adaptation to environments, though it is actually Lamarck who first conceived of such a concept Difference? Darwin had a population emphasis Historical context Charles Darwin (1809-1882) HMS Beagle (1831-1836) Darwin Developed the basis his theory based on his observations of the principles of botany, geology, and zoology while on a five year research voyage He gained great insights while visiting the Pacific Islands, Galapagos Archipelago, and South America He was afraid to share his work so he waited to publish until he heard of another scientist, Wallace, who was developing a theory similar to his own Wallace Independently developed a theory of evolution by natural selection Terms to know: Evolution: Descent with modification Natural Selection: Individuals with certain heritable traits leave more offspring Evolutionary Adaptation: Characteristics that enhance survival Evolution: Descent with Modification Evolution: Premises 1. Struggle for survival ◦ Competition between individuals ◦ Over production (Malthus) Evolution: Premises 2. Variations Exist Evolution: Premises 3. Many Variations are heritable Evolution by Natural Selection 1. Natural selection is the differential reproductive success of among individuals 2. Variations exist; some represent adaptive traits that increase reproductive success 3. Many of these are heritable 4. Over time, this can increase the adaptation of organisms to their environment 5. Environmental changes may result in adaptation of a species to these new conditions. Natural Selection: Diversity derived from wild mustard Adaptation: the result of natural selection *The result of natural selection is adaptation Adaptation – heritable trait that increase an organism’s likelihood of surviving and reproducing in its environment Example: Desert animals exhibit extraordinary adaptations, both physical and behavioral, to their environment "In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment." -Charles Darwin, The Origin of Species Adaptation Adaptation: Camouflage Not an adaptation Artificial Selection (Not the same) Breeding plants and animals for specific traits Darwin was a fan of fancy pigeons Fitness 1. Individual organisms are selected 2. Populations evolve! Remember, individuals live or die. They do not evolve! Evidence for evolution Evolution is supported by an overwhelming amount of scientific evidence Let’s take a look at some direct observations of evolutionary change . . . How does selection drive changes in a population? Paul Muller discovered DDT in 1939. Nobel Prize 1948 By 1945, 3m pounds of DDT produced/year! Examples of Selection provide evidence of Evolution . . . Examples of Natural Selection 30-60 generations later . . . 14% heavier; average age at maturity higher More examples…. Salmon ◦ 80% mortality ◦ Evolving to be smaller and more torpedo-shaped ◦ Population is 30% smaller over 50 years The Peppered Moth Biston betularia Evolution of drug resistance A drug does not create a resistant pathogen It selects for existing resistant pathogens And so with evolution: Evolution does not create novel life forms Nature selects from existing variants Need more evidence? Viruses Bacteria Resistance The Red Queen Hypothesis Forewarned is forearmed . . . A. Biogeography Closely related species tend to be found in the same region Pangea, Laurasia and Gondwanaland What is the significance of Biogeography? The geographical distribution of species only makes sense in light of evolutionary past What are specific examples? Marsupial Mammals in Australia Finches in Galapagos Fruit flies in Hawaii Convergent Evolution So how can disjunct regions have species that appear similar, though are not closely related? Different geographic regions, different mammalian “brands” CONVERGENT EVOLUTION Same problem, same solution B. Vestigial Organs C. Comparative Embryology D. Homologous Structures: Similar Anatomy(relatedness) Different Functions (adaptation) NOT EVIDENCE FOR EVOLUTION Analogous Structures: Similar Functions (adaptation) Different Anatomy (lack relatedness) E. Comparative Biochemistry Molecular Data and the Evolutionary Relationships of Vertebrates Evidence Summary A. B. C. D. E. F. G. Direct Observations of Evolutionary Change Biogeography Vestigial Organs Comparative Embryology Homologies Comparative Biochemistry Molecular Biology Natural Selection Review A. Product is adaptation of populations to their environment B. Does not “create” options C. Is an Editing Process Natural Selection Premises Review A. Variation must exist A. Variation must lead to differential reproductive success A. Variation must be heritable. Descent with Modification Evidence of Biblical Flood? (Theology) Some people think that the Grand Canyon is evidence of the great flood told in the story of Noah in the bible. I’ll leave it up to you to decide what you believe on this one.