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Principles of Evolution

Principles of Evolution. Chapter 24. Classification of Humans. Kingdom Animalia Phylum Chordata Class Mammalia Order Primates Family Hominidae Genus Homo Species sapiens. Challenges to Early Beliefs. • Biogeography - discovery of species in isolated locales

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Principles of Evolution

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  1. Principles of Evolution Chapter 24

  2. Classification of Humans • Kingdom Animalia • Phylum Chordata • Class Mammalia • Order Primates • Family Hominidae • Genus Homo • Species sapiens

  3. Challenges to Early Beliefs • Biogeography - discovery of species in isolated locales • Comparative morphology - similarities between animals, parts with no functions • Fossils - deep layers with simple fossils, overlying layers with increasing complexity

  4. Charles Darwin • Proposed the theory of evolution by way of natural selection • Influenced by • Observations made while naturalist on H.M.S. Beagle • Conversations with other naturalists • Writings of Thomas Malthus

  5. Variation in Populations • Individuals do not evolve; populations do • Members of a population have similar traits • Details of traits vary among individuals • Some variation results from genetic differences (different alleles)

  6. Mutation • A heritable change in DNA • Most are harmful • Some are neutral • A few are beneficial

  7. Natural Selection • Individuals vary • Some variations are heritable • Some versions of traits increase fitness • Natural selection is the difference in survival and reproduction in individuals who have different versions of a trait

  8. Evolving Populations • A population is evolving when some forms of a trait are becoming more or less common relative to the other forms • Over time, shifts in the makeup of gene pools have been responsible for the amazing diversity of life forms on Earth

  9. Other Changes to Gene Pool • Genetic drift • Founder effect • Virtually no Native Americans with type B blood • Gene flow • Physical movement of alleles • Helps keep neighboring populations genetically similar

  10. Species • A genetic unit consisting of one or more populations of organisms • Members can interbreed and produce fertile offspring under natural conditions • Reproductively isolated from other species

  11. Speciation time A time B time C time D time

  12. Fossils • Usually hard parts • Form in sedimentary rock • Stratification • Fossil record is biased

  13. Biogeography Distribution of plants and animals Plate tectonics

  14. Comparative Morphology • Homology • Similarity in body parts in different organisms • Attributable to descent from a common ancestor • Analogy • Similarity in body parts in different organisms • Attributable to similar environmental pressures

  15. Homologous Structures Vertebrate forelimbs

  16. Comparative Embryology • Early vertebrate embryos strongly resemble one another • Same plan of development Fish Reptile Bird Mammal

  17. Proportional Skull Changes Chimpanzee Human

  18. Evidence from Comparative Biochemistry • Molecular clocks • Neutral mutations • Protein comparisons • Cytochrome C • Nucleic-acid comparisons • Base-pairing of DNA or RNA from one species to another

  19. Extinctions - End of the Line • Background extinction • Local changing conditions • Mass extinction • Catastrophic global event • 65 million years ago • Probably asteroid impact

  20. Adaptive Radiation • New species of a lineage moves into a wide range of habitats • Has occurred in the human lineage • Homo habilis remained in Africa • H. erectus went to Europe, Asia • H. sapiens evolved by 100,000 years ago

  21. Trends in Human Evolution • Upright walking • Refined hand movements • Enhanced daytime vision • Changes in dentition • Changes in brain and behavior

  22. Comparison of Skeletal Organization

  23. Trend toward Longer Life Spans and Dependency

  24. From Primates to Hominids • 60 million years ago • Tropical forests • Small rodents, tree shrews • 54 - 38 million years ago • Primates in trees • 36 million years ago • Tree-dwelling anthropoids • 10 - 5 million years ago • First hominoids

  25. Early Earth • Primitive atmosphere • H2 • N2 • CO • CO2 • Probably no O2

  26. Complex Compounds Form Organic compounds may have: • Formed when lightning interacted with gases in early atmosphere • Assembled on clays in tidal flats • Formed near hydrothermal vents

  27. Emergence of First Living Cells • Self-Replicating Systems • RNA • DNA • Plasma Membranes • Proto-cells

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