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Chapter 7: Biological Diversity

Chapter 7: Biological Diversity. What is Biological Diversity. Bio diversity refers to the variety of life forms in an area. Expressed as # of species in an area Or # of genetic types in an area. Biodiversity Definition: Variety of different species. Species Diversity :

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Chapter 7: Biological Diversity

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  1. Chapter 7: Biological Diversity

  2. What is Biological Diversity • Bio diversity refers to the variety of life forms in an area. • Expressed as # of species in an area • Or # of genetic types in an area

  3. Biodiversity Definition: Variety of different species.

  4. Species Diversity: Number of different species and their relative abundances in a given area.

  5. Genetic Diversity: • Variety in the genetic makeup of organisms of a species that allow the species to reproduce and gain a competitive advantage

  6. Ecosystem Diversity: The variety of forests, deserts, grasslands, oceans, lakes, etc.

  7. Why Should We Care About Biodiversity? • Use Value: For the usefulness in terms of economic and ecological services. • Nonuse Value: existence, aesthetics, bequest for future generations. Figure 10-3

  8. Importance of Diversity • Stability- stable environment • Genetic reserves- genetic diversity • Medicinal- medicines • Agricultural- food • Industrial- building homes; things we use • Scientific- experimental; new technology • Aesthetic- beautiful • Ethical- what should we do regarding the environment • Religious- religious beliefs regarding environment

  9. Biological Evolution • New species arise as a result • of competition for resources • the difference among individuals in their adaptations to environmental conditions • Four processes lead to evolution • Mutation, natural selection, migration and genetic drift

  10. Mutation • Genes are inherited from one generation to the next • Genes made up of DNA • DNA made up bases A,C,G,T • How these letters are combined determines the massage passed to a cell

  11. Mutation • When cells divide • DNA is reproduced • Each cell gets a copy • If an error occurs in the reproduction of DNA it gets passed to new cells • DNA change = Mutation

  12. Mutation

  13. Natural Selection • Some individuals may be better suited to the environment than others. • Those better able to survive and reproduce leave more offspring. • Their descendants form a larger proportion of the next generation.

  14. Natural Selection • Four primary characteristics • Genetic variability • Environmental variability • Differential reproduction that varied with the environment • Influence of the environment on survival and reproduction

  15. Natural Selection • The accumulation of changes may lead to reproductive isolation • Resulting in a new species • Species = a group of individuals that can reproduce with each other.

  16. Migration and Geographic Isolation • Two populations become geographically isolated for a long time • Enough change accumulates so that they no longer reproduce • Two new species have formed • Migration important evo process (e.g. Hawaii honey creeper and Darwin’s finches)

  17. Adaptive Radiation • Galapagos Islands • Darwin observed numerous finches related to a single finch elsewhere • Each with a different niche • Process called adaptive radiation

  18. Founder Effect and Genetic Drift • Founder effect • Small # of individuals are isolated from larger pop. • Less genetic variation than original pop • Which characteristics present affected by chance • Genetic drift is changes in freq of a gene simply by chance • Ind may NOT be better adapted

  19. 10 species; 100 ind, 87 elephants, 9 sp w/ 2 ind each

  20. 10 species; 100 ind, 10 ind each species

  21. Species Diversity Merely counting the number of species is not enough to describe biological diversity.

  22. The Evolution of Life on Earth • Earliest fossils 3.5 billion years old • Photosynthetic relative of bacteria • Released large amounts of oxygen into the atmosphere

  23. The Evolution of Life on Earth • Cambrian Period • 600 million years- 500 my • Earliest multicellular organisms • Shells, gills, filters, efficient guts and circulatory system. • Life remained in oceans

  24. The Evolution of Life on Earth • Innovations for life on land • Structural support • Internal aquatic environment • Means for exchanging gases with air • A moist environment for reproduction system

  25. The Evolution of Life on Earth • Devonian Period • 420–360 million years ago • First animals on land = crossopterygian • Gave rise to the amphibians • Still tied to water for reproduction • Modern species include frogs, toads, newts, limbless water “snakes”

  26. Early Life on Land

  27. The Evolution of Life on Earth • Reptiles • Freed from water by evolving a watertight egg • Originate in the Carboniferous (375 mya) • Wide spread by the Jurassic (185 mya) • Two orders of dinosaurs that gave rise to mammal and birds.

  28. The Evolution of Life on Earth • Mammals • More capable brain and faster metabolism • Placental uterus one key to mammalian success

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