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Lesson 5: Biological Diversity

Lesson 5: Biological Diversity. Big Question Big Question: Can We Save Endangered Species and Keep Biological Diversity High?. What Is Biological Diversity?. Biological diversity is the wealth of species that live on Earth

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Lesson 5: Biological Diversity

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  1. Lesson 5: Biological Diversity Big Question Big Question: Can We Save Endangered Species and Keep Biological Diversity High?

  2. What Is Biological Diversity? Biological diversity is the wealth of species that live on Earth Commonly expressed as the number of species or genetic types in an area

  3. Biological Evolution • An important question about biological diversity is "How did it all come about?" • In the 19th century, Charles Darwin proposed an explanation that became known as biological evolution • It is the change in inherited characteristics of a population from generation to generation • Ultimately, it can result in new species

  4. Mutation • Deoxyribonucleic acid (DNA) carries inherited information from one generation of cells to the next • The chemical information for a single characteristic is a gene • The genetic makeup of an individual or group is a genotype

  5. Selection Change is not always for the better. Mutation can result in a new species whether or not that species is better adapted to the environment than its parent species. Individuals with characteristics making them better able to survive and reproduce leave more offspring than others; they are more fit. This process of increasing the proportion of better-adapted offspring is natural selection.

  6. Migration Geographic isolation can lead to divergent evolution. The two populations may change so much that they can no longer reproduce together.

  7. Genetic Drift Sometimes changes in genetic makeup of a population occur simply from chance: drift. Genetic drift can be a problem for rare or endangered species. • Lower fitness traits may dominate. • Small size of the population reduces genetic variability.

  8. Island Ecology • Islands have fewer species than continents, and the smaller the island, the fewer the species, on average. • Also, the farther away an island is from a continent, the fewer species it will have.

  9. Adaptive Radiation Isolation on remote islands can lead to adaptive radiation. An example is Hawaiian Honeycreepers.

  10. Basic Concepts of Biological Diversity

  11. How many Species on Earth? See the Wikipedia article on Species. www.wildlifeinstitute.org/press_gallery.htm http://www.worldproutassembly.org/

  12. How many Species on Earth?

  13. What Can We Do to SaveEndangered Species? How many species are threatened with extinction? According to the IUCN Red Book of Threatened Species • 23% of mammals, 12% of birds, 4% of reptiles, 31% of amphibians, and 3% of fish; and • 3% of plants.

  14. Endangered and Threatened Species What does it mean to call a species endangered or threatened? Endangered species means any species which is in danger of extinction throughout all or a significant portion of its range. Threatened species means any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

  15. Why Save Endangered Species? Taken from http://www.fws.gov/endangered/

  16. How a Species BecomesEndangered and Extinct • Extinction is the rule of nature • Local extinction is when a species disappears from a part of its range • Global extinction is when a species can no longer be found anywhere • Rates of extinctions have varied greatly over geologic time

  17. Mass Extinctions The fossil record suggests that there have been several periods of mass extinction and other periods of rapid evolution of new species

  18. Causes of Mass Extinction • Six major mass extinctions occurred during the past 550 million years • The end of the dinosaurs about 65 million years ago – asteroid impact? • Megafauna extinctions 20,000–10,000 years ago at the end of the last great continental glaciation period • The rate of extinctions has increased greatly since the Industrial Revolution

  19. How People Cause Extinctionsand Affect Biological Diversity Some ways we cause extinction: • hunting or harvesting • disrupting or eliminating habitats • introducing exotic species • polluting

  20. The Good News: The Statusof Some Species Has Improved Success stories include • Elephant seals; • Sea otters; • Recovery of bird populations after the ban on DDT; and • Blue and gray whales. Link: "Living with alligators: A Florida reality" at http://edis.ifas.ufl.edu/UW230

  21. Chapter 5: Biological Diversity Questions? E-mail your TA. eschelp@u.washington.edu

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