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APES – Chapter 7 - Biodiversity

APES – Chapter 7 - Biodiversity

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APES – Chapter 7 - Biodiversity

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  1. APES – Chapter 7 - Biodiversity

  2. Definition • The diversity of life forms in the environment • 3 scales within a region • A) ecosystem • B) species • C) genetic

  3. Species diversity varies among ecosystems

  4. How many species live on Earth? • 2 million named to date • Current estimates = 5 to 100 million, but most say 10 million • Challenges? • active only at night • Live in inaccessible locations • Require a microscope to be seen

  5. Measuring species at a local or regional scale • Species richness and species evenness • Number of species in a given area vs relative proportion of individuals within the different species • High species evenness – if its species are all represented by similar numbers of individuals • Which community is considered more diverse? • Both may decline after a human disturbance • Measurement of these 2 indicators gives environmentalists a baseline to evaluate change

  6. Shannon’s index of diversity Example 1 Imagine a community of 100 individuals that are evenly divided among four species, so that the proportions(pi) of the species all equal 0.25. Calculate H for this community. Example 2 Now imagine another community of 100 individuals that also contains four species, but in which one species is represented by 94 individuals and the other three species are each represented by 2 individuals. Calculate H for this community.

  7. Evolution is the mechanism underlying biodiversity • Change in genetic composition of a population over time. • Microevolution – evolution on a small scale • Macroevolution – genetic changes that give rise to new species or new genera etc. • Evolution depends on genetic diversity

  8. Creating genetic diversity • Genes • Genotype • Mutation and recombination – change in DNA and crossing over • Mutations can be detrimental or improve an organism’s chance of survival • Ex) dusky-headed conure vs mosquito

  9. Genotype vs Phenotype • Actual set of traits expressed in that individual • Determined by genes or a combination of genes and environment • Ex) eye color vs gender in some turtle and crocodile species or morphology in daphnia

  10. Evolution by Artificial Selection • Plants and animals bred for traits we desire • Can produce unintended results – selection for herbicide resistance in weeds or selection for drug-resistant bacteria

  11. Evolution by Natural Selection • Determined by the environment, not humans • Both require that individuals vary in their traits and that these variations are capable of being passed on to the next generation • N.S. favors any combination of traits that improves an individual’s fitness(its ability to survive and reproduce) • Traits that improve an individual’s fitness are called adaptations • N.S. can favor multiple solutions to a particular environmental challenge

  12. Evolution by Random Processes • Mutation, genetic drift, bottleneck effect, and founder effect

  13. Speciation and Extinction Determine Biodiversity • Allopatric vs Sympatric Speciation

  14. Factors determining the pace of evolution • For each of the following factors, create a line graph that depicts the ability of a species to adapt to change- lesser  greater on x axis • Rate of environmental change(slow vs fast – on y axis) • Genetic variation(less vs more – on y axis) • Population size(small vs large – on y axis) • Generation time(long vs short – on y axis)

  15. Genetically Modified Organisms

  16. Evolution shapes ecological niches and determines species distributions

  17. Fundamental vs Realized Niche • Biotic factors can also limit the physical location of organisms • Such as .... • Presence of competitors • Presence of predators • Presence of disease • Result is the organism’s realized niche

  18. Niche generalists vs specialists • Example – an insect that feeds on a wide variety of plants versus one that feeds on a single variety of plant • Which do you think would be more vulnerable to extinction if conditions in their environment were to change?

  19. Environmental Change and Species Distribution

  20. Environmental Change and Species Extinctions • Species cannot adapt to changes or move to a more favorable environment -- no favorable environment that is geographically close enough to move to -- alternative favorable environment may already be occupied by other species -- environmental change may occur so rapidly that the species does not have time to evolve new adaptations

  21. The Five Global Mass Extinctions

  22. The Sixth Mass Extinction

  23. Arguments in favor of conserving Earth’s biodiversity

  24. Medicinal Plants • Dung of the Devil – H1N1 • Salicylic Acid – Willow tree • Drugs to treat childhood leukemia and Hodgkin’s disease – Rosy periwinkle • Antiviral and anticancer drugs – Mayapple • Anti-inflammatory and anti-tumor drugs – invertebrates found in coral reefs

  25. Working Toward Sustainability • The Nature Conservancy – uses grants and private donations to purchase privately owned natural areas or to buy development rights to those areas • Declines in the populations of many fish and shellfish has steered their focus to coastal ecosystems • They have purchased harvesting and exploitation rights and use them as a conservation tool

  26. Legislation • 1. CITES – Convention On International Trade in Endangered Species of Wild Flora and Fauna(1973) – no living specimen or “wildlife product” could be traded if it came from an endangered or threatened species • 2. Endangered Species Act of 1973 – Identifies threatened and endangered species in the US, and puts their protection ahead of economic considerations • 3. Marine Mammals Protection Act of 1972 – protects marine mammals from falling below their optimum sustainable population levels