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Origins of Biological Diversity: Understanding Species and Evolution

Explore the concepts of species, microevolution, macroevolution, reproductive barriers, geographic isolation, adaptive radiation, embryology, fossils, geologic time scale, continental drift, mass extinction, and modern taxonomy.

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Origins of Biological Diversity: Understanding Species and Evolution

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  1. Chapter 15 Origins of Biological Diversity

  2. What is a Species? • Species – Distinct form of life • Creates much diversity or variety within life • Biological Species concept – defines species as a population or group of populations whose members have the ability to reproduce

  3. Micro and Macro Evolution • Microevolution – changes or mutations within the genes of a population • Macroevolution – major biological changes evident in the fossil record • Ex. Extinction of a species, new features like wings

  4. Reproductive Barriers Between Species • Reproductive Isolation – condition in which a reproductive barrier keeps two species from interbreeding • Timing – Different breeding seasons • Behavior – Different courtship or mating behaviors • Habitat – Adapted to different habitats in the same general location • Physical differences – reproductive structures are physically incompatible • Fertility – unable to reproduce

  5. Geographic Isolation and Speciation • Geographic Isolation – separation of populations as a result of geographicchange or migration to geographically isolated places • Ex. Mountain forms, glacier movement • This can lead to new evolutionary developments and then new species • Speciation – formation of a new species

  6. Geographic Isolation and Speciation

  7. Adaptive Radiation • Adaptive Radiation – evolution from a common ancestor of many species adapted to diverse habitats • Ex. Hawaiian Islands • Some species go through a modification process in which existing adaptations are refined as well as adaptation of existing structures to new functions • Ex: Exoskeleton of arthropods years ago – protection • Today – protection and prevents water loss

  8. Adaptive Radiation

  9. Embryology • Embryology – study of the processes of multicellular organisms as they develop from fertilized eggs to fully formed organisms • The developmental timing of organisms can cause variation • Ex. Salamanders that live in trees have shorter toes and more webbing than those that live on the ground; the growth of the feet of the tree dwellers ends sooner than those that live on land

  10. Fossils • Fossils – preserved remains or markings left by an organism that lived in the past • Footprints, eggs, bones, etc • Fossil Record – Chronological collection of life’s remains in sedimentary rock layers • Supplies much information about macroevolution

  11. Geologic Time Scale • Geologic Time Scale – four distinct ages of earth’s history • Eras • Precambrian, Paleozoic, Mesozoic, and Cenozoic • Periods • Ex: Jurassic – Dinosaurs

  12. Dating Fossils • Radiometric Dating – based on the measurement of certain radioactive isotopes in objects • Half-life – the number of years it takes for 50% of the original sample to decay

  13. Continental Drift • Continental Drift – motion of continents about Earth’s surface on plates of crust floating on the hot mantel • Paleozoic Era – all land masses together created “Pangea” with huge environmental changes • Mesozoic and Cenozoic Eras – land masses begin to drift apart • Species must now adapt and huge macroevolution changes occurred

  14. Mass Extinction • Mass Extinction – episode of great loss of species • Ex: Dinosaurs • Leads to adaptive radiation of surviving species

  15. Modern Taxonomy • Taxonomy – branch of biology that deals with identifying, classifying, and naming species • Classification – organizing species into larger groups of related species

  16. Modern Taxonomy • Carolus Linnaeus • Binomial Nomenclature – two part naming system • Genus and species name • Ex: Domesticated dogs Genus: Canis Species: familiaris Wolves Genus: Canis Species: lupus

  17. 7 Levels of Classification • 1. kingdom • 2. phylum • 3. class • 4. order • 5. family • 6. genus • 7. species • When moving down this list, organisms in each classification level are more closely related

  18. The Three Domains of Life • Domain – Broadest category of classification • Archaea, Bacteria, Eukarya • Kingdoms – category of classification after domains • 4 kingdoms within Eukarya domain • Animals, Plants, Fungi, Protists • 1 kingdom within Archaea domain • Archaebacteria • 1 kingdom within the Bacteria domain • Eubacteria

  19. The Idea of Evolution • Charles Darwin – Studied the similarities and differences between organisms at the Galápagos Islands • He became convinced that organisms change over time • Evolution – The development of new types of organisms from preexisting types of organisms • Natural Selection - The process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do

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