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The Theory of Evolution

The Theory of Evolution. UNIT 1 Evolution & Classification. Life’s Diversity (ch 15). There are millions of different organisms on earth, the variety that exists among organisms is called… BIOLOGICAL DIVERSITY . The questions many asked… What makes organisms so diverse?

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The Theory of Evolution

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  1. The Theory of Evolution UNIT 1 Evolution & Classification

  2. Life’s Diversity (ch 15) • There are millions of different organisms on earth, the variety that exists among organisms is called… BIOLOGICALDIVERSITY. • The questions many asked… • What makes organisms so diverse? • Could these diverse organisms be related in some way? • How?

  3. Theory of Evolution • First of all a quick reminder of the term THEORY…. • Well supported and test explanation that unifies a broad range of observations. • Evolution is a THEORY that states… • GRADUAL change over TIME, is the process by which modern organisms have descended from ancient organisms

  4. “Isn’t Evolution Just a Theory?” • PBS VIDEO (Evolving Ideas)… • Video: Isn’t Evolution Just a Theory? http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_1.html

  5. Influences in EVOLUTION • LAMARK (1809) • First to propose how organisms change, but theory is flawed • Use and disuse of organs cause organism to change; organism change because they need to change; Ex: Bird doesn’t fly loses wings • DARWIN (1831) • Sets sail on HMS Beagle, the voyage provides evidence that leads to his Theory of Evolution. • LYELL (1833) • Geologist proposing the Earth has changed over time; thus organisms must also change

  6. Darwin’s 5 year voyage around the Earth

  7. Darwin’s Observations • Collected Fossils…. • Fossils he collected RESEMBLED organisms that were currently living. • Galapagos Islands west of South America • The Island had different climates • Tortoises on 3 different islands were different on each Island to suit their climate

  8. “Who Was Charles Darwin?” • PBS VIDEO (Evolving Ideas) • Video: Who Was Charles Darwin? http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_2.html

  9. Darwin’s Theory • Natural Variation… there are differences among species; individual organisms differ; alleles • Struggle for Existence… All organisms produce more offspring than can survive; therefore must compete for limited resources. • Natural Selection“Survival of the Fittest”…individuals best adapted for the environment survive and pass on traits to offspring. • Adaptation… any inherited characteristic that INCREASES chance for survival

  10. Natural Selection • Evolution occurs because of Natural Selection • Over time natural selection (nature) results in changes in the INHERITED characteristics. • These changes are inherited and increase that species FITNESS in its environment. • Organisms more FIT for the environment, survive, reproduce, and pass on their genes (alleles). • Principle of Common Descent • States that all species… living and extinct… were derived from common ancestors

  11. “How Does Evolution Really Work?” • PBS VIDEO (Evolving Ideas) • Video: How does Evolution Really Work? http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_4.html

  12. Evolution of Population • Natural Selection takes place because of genetic VARIATION that exists in a population • POPULATION – group of individuals of the same species that live in the same area • GENE POOL – common group of genes shared by a population (all the genetic information; alleles) • Sources of Genetic Variation • Mutations – any change in the DNA sequence • Gene Shuffling – change in allele frequency in a population; formation of gametes and crossing over allow for new gene combination (more variation)

  13. Genetic Change • Natural Selection acts on the PHENOTYPE • It affects which individuals having different phenotypes survive and reproduce • This is how natural selection determines which alleles are passed to next generation • It changes the RELATIVE FREQUENCY of alleles in a population ( the number of one allele compared to the other in a population)

  14. Gene Pool • How would the gene pool be affected if these mice lived in an environment where the brown fur mice were more camouflaged? Black Allele Brown Allele 48% heterozygous black 16% homoz black 36% homozygous brown

  15. Evolution vs Genetic Equilibrium • Genetic Equilibrium (Allele frequencies stay the same) = NO Evolution • Hardy-Weinberg Principle Allele Frequencies will remain the same ONLY if ALL of the following… • Random Mating (equal opportunity to reproduce) • Very Large Population • No migration in or out of population • No Mutations • No natural selection ( no phenotype has advantage)

  16. Speciation • How can natural selection and evolution lead to the formation of a new species (speciation) • Species is defined as a group of organisms that breed and produce fertile offspring (share the same gene pool) • New species are created when a population evolves and becomes reproductively isolated (can not mate)

  17. Reproductive Isolation • Behavioral Isolation • They could breed, but do not because of differences in mating rituals (song birds) • Geographic Isolation • Geography separates 2 species that use to breed (rivers, mountains) • Temporal Isolation • Species reproduce at different times (release pollen)

  18. “How Do We Know Evolution Happens?” • PBS VIDEO (Evolving Ideas) • Video: How Do We Know Evolution Happens? http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_3.html

  19. FOSSILS Show similar extinct organisms GEOGRAPHIC Similar organisms in different locations HOMOLOGOUS STRUCTURES Similar body structures with different functions Some from common ancestors VESTIGIAL ORGANS Organs that once had functions but not now Humans appendix EARLY DEVELOPMENT Many vertebrates look similar as embryos BIOCHEMICAL DNA, RNA are similar Use of ATP Evidence for Evolution

  20. TURTLE ALLIGATOR BIRD MAMMAL HOMOLOGOUS STRUCTURES PRIMITIVE FISH

  21. “Why is Evolution Controversial Anyway?” • PBS VIDEO (Evolving Ideas) • Video: Why is Evolution Controversial Anyway? http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_7.html

  22. Classification Ch 18

  23. CLASSIFICATION • Taxonomy is the classifying of organisms and assigning a universally accepted name. • Provides LOGICAL means for naming organisms • COMMON NAMES (misleading, differ from region, lengthy) • EX: Groundhog is not a HOG, Sea Horse is not a HORSE • ARISTOTLE: Classified organisms in 2 categories… • Plants or Animals • LINNEAUS: Binomial Nomenclature • Two-Word (Latin) Naming System • Currently used today as Scientific Name • EX: Man is Homo sapiens

  24. Scientific Name (Binomial Nomenclature) • FIRST WORD: Genus (noun) • Broader category and may include many species • EXAPMPLE: Homo (noun) means man • SECOND WORD: Species (adjective) • More specific category • EXAMPLE: Sapiens (adjective) means wise or thinking • Correct way to write • Homo sapiens(italics when typed) • Homo sapiens (underlined when hand written)

  25. How Do We Classify? • Categories (TAXA) based on… • Structural and Functional similarities • Lines of evolutionary descent • CLADOGRAM – shows evolutionary relationship • Similarities in DNA and RNA (biochemical) • MOLECULAR CLOCK – use DNA to estimate how long species have evolved separately • Developmental Similarities (embryological)

  26. Explain the differences between traditional classification and cladograms (modern classification). Appendages Conical Shells Crustaceans Gastropod Crab Crab Limpet Limpet Barnacle Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva TRADITIONAL CLASSIFICATION CLADOGRAM

  27. Classification: Broad to Specific (Scientific Name: Homo sapiens) • KINGDOM (ex: Animal) • Kids • PHYLUM (ex: Chordate) • Prefer • CLASS (ex: Mammal) • Candy • ORDER (ex: Primates) • Over • FAMILY (ex: Hominid) • Fresh • GENUS (ex: Homo) • Green • SPECIES (ex: sapiens) • Spinach KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Carnivora FAMILY Ursidae GENUS Ursus SPECIES Ursus arctos

  28. “Your Turn” • Turn to a friend. • Create your own Mnemonic device to remember classification from Kingdom thru Species…

  29. Kingdoms • EUBACTERIA • ARCHAEBACTERIA • PROTISTA • FUNGI • PLANTEA • ANIMALIA

  30. DOMAIN ARCHAEA DOMAIN EUKARYA Kingdoms Eubacteria Archaebacteria Protista Plantae Fungi Animalia DOMAIN BACTERIA

  31. Classification of Living Things Plantae Eukaryote Multi… Autotroph Mosses, ferns, flowering plants Eukarya Animalia Eukaryote Multi… Heterotroph Sponges, worms, insects, fishes, mammals DOMAIN KINGDOM CELL TYPE CELL STRUCTURES NUMBER OF CELLS MODE OF NUTRITION EXAMPLES Bacteria Eubacteria Prokaryote Cell walls w/ peptidoglycan Unicellular Autotroph Heterotroph Streptococcus, E. coli Archaea Archaebacteria Prokaryote Cell walls w/out peptidoglycan Unicellular Autotroph Heterotroph Halophiles Fungi Eukaryote some unicell… Most multi… Hetero… Mushrooms, yeasts Protista Eukaryote Most unicell… some multi… Autotroph Heterotroph Amoeba, Paramecium,

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