The Importance of Biodiversity and Evolution in Earth's Natural Capital

1. CHAPTER 4 BIODIVERSITY & EVOLUTION

2. Biodiversity Is a Crucial Part of the Earth’s Natural Capital • Species: set of individuals who can mate and produce fertile offspring • 8 million to 100 million species • 1.9 million identified • Unidentified are mostly in rain forests and oceans

3. Classifying Homo Sapiens

4. Natural Capital: Major Components of the Earth’s Biodiversity

5. Major Biomes Denver Baltimore San Francisco Las Vegas St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest

6. Biological Evolution by Natural Selection Explains How Life Changes over Time • Fossils • Physical evidence of ancient organisms • Reveal what their external structures looked like • Fossil record: entire body of fossil evidence • Only have fossils of 1% of all species that lived on earth

7. Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era Fig. 4-6, p. 86

8. Biological Evolution by Natural Selection Explains How Life Changes over Time • Biological evolution: how earth’s life changes over time through changes in the genetic characteristics of populations • Darwin: Origin of Species • Natural selection: individuals with certain traits are more likely to survive and reproduce under a certain set of environmental conditions • Verification: huge body of evidence

9. Evolution of Life on Earth Supplement 5, Fig. 2, p. S18

10. Evolution by Natural Selection Works through Mutations and Adaptations • Populations evolve by becoming genetically different from other populations • Genetic variations • First step in biological evolution • Occurs through mutations in reproductive cells • Mutations: random changes in DNA molecules

11. Evolution by Natural Selection Works through Mutations and Adaptations • Natural selection: acts on individuals • Second step in biological evolution • Adaptation may lead to differential reproduction • Genetic resistance: ability of one or more members of a population to resist a chemical designed to kill it

12. (a) A group of bacteria, including genetically resistant ones, are exposed to an antibiotic (d) Eventually the resistant strain replaces all or most of the strain affected by the antibiotic Evolution by Natural Selection (c) The genetically resistant bacteria start multiplying (b) Most of the normal bacteria die Normal bacterium Resistant bacterium Fig. 4-7, p. 87

13. Adaptation through Natural Selection Has Limits • Adaptive genetic traits must precede change in the environmental conditions • Reproductive capacity • Species that reproduce rapidly and in large numbers are better able to adapt • “Survival of the fittest” is not necessarily “survival of the strongest” • Organisms do not develop traits out of need or want • No grand plan of nature for perfect adaptation

14. Geologic Processes Affect Natural Selection • Tectonic plates affect evolution and the location of life on earth • Locations of continents and oceans have shifted • Species physically move, or adapt, or form new species through natural selection • Earthquakes • Volcanic eruptions

15. Movement of the Earth’s Continents over Millions of Years Fig. 4-8, p. 89

16. 225 million years ago Fig. 4-8, p. 89

17. 135 million years ago Fig. 4-8, p. 89

18. 65 million years ago Fig. 4-8, p. 89

19. Present Fig. 4-8, p. 89

20. Climate Change and Catastrophes Affect Natural Selection • Ice ages followed by warming temperatures • Collisions between the earth and large asteroids • New species • Extinctions

21. Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years Fig. 4-9, p. 89

22. How Does A New Species Evolve? • Speciation: one species splits into two or more species • Reproductive isolation: mutations and natural selection in isolated populations lead to inability to produce viable offspring when members of two different populations mate • Geographic isolation: one mechanism of reproductive isolation; happens first; requires physical isolation of populations for a long period

23. Geographic Isolation Can Lead to Reproductive Isolation Fig. 4-10, p. 91

24. Extinction • Extinction • Biological extinction • Local extinction • Endemic species • Found only in one area • Particularly vulnerable • Background extinction: ongoing; low rate of extinction • Mass extinction: rapid and devastating; 3-5 times over 500 million years

25. Changing the Genetic Traits of Populations • Artificial selection • Use selective breeding/crossbreeding • Genetic engineering, gene splicing • Consider • Ethics • Morals • Privacy issues • Harmful effects

26. Artificial Selection Fig. 4-C, p. 92

27. Genetically Engineered Mice Fig. 4-D, p. 92

28. Species Diversity: Variety, Abundance of Species in a Particular Place • Species diversity is a combination of: 1. Species richness: • The number of different species in a given area 2. Species evenness: • Comparative number of individuals

29. Species Diversity: Variety, Abundance of Species in a Particular Place • Diversity varies with geographical location • The most species-rich communities • Tropical rain forests • Coral reefs • Ocean bottom zone • Large tropical lakes • Swamps & estuaries

30. Species-Rich Ecosystems Tend to Be Productive and Sustainable • Species richness seems to increase productivity and stability or sustainability, and provide insurance against catastrophe • Scientists are unable to determine exactly how much species richness is necessary for full productivity & sustainability

31. Each Species Plays a Unique Role in Its Ecosystem • Ecological niche, • Pattern of living: everything that affects survival and reproduction • Water, space, sunlight, food, temperatures • Generalist species • Broad niche: wide range of tolerance • Specialist species • Narrow niche: narrow range of tolerance

32. Specialist Species and Generalist Species Niches Fig. 4-13, p. 95

33. Specialized Feeding Niches of Various Bird Species in a Coastal Wetland Herring gull is a tireless scavenger Ruddy turnstone searches under shells and pebbles for small invertebrates Brown pelican dives for fish, which it locates from the air Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Black skimmer seizes small fish at water surface Piping plover feeds on insects and tiny crustaceans on sandy beaches Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Louisiana heron wades into water to seize small fish Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Knot (sandpiper) picks up worms and small crustaceans left by receding tide Fig. 4-14, p. 96

34. Species Can Play Five Major Roles within Ecosystems • Native species • Nonnative species • Indicator species • Keystone species • Foundation species

35. Indicator Species Serve as Biological Smoke Alarms • Indicator species • Provide early warning of damage to a community • Can monitor environmental quality • Trout • Birds • Butterflies • Frogs

36. Keystone Species Play Critical Roles in Their Ecosystems • A keystone species is a species that has a disproportionately large effect on community structure relative to its biomass or abundance. • Pollinators • Top predators

37. Foundation Species Help to Form the Bases of Ecosystems • A foundation species plays a unique, role in creating and defining a community. Often, foundation species modify the environment for themselves. This can result in the environment being able to support the other organisms that form the community • Elephants • Beavers • Coral • Kelp

38. Compare: Foundation and Keystone Species • Keystone species differ from foundation species in two main ways: • they are more likely to belong to higher trophic levels (to be top predators), and • they act in more diverse ways than foundation species, which “just” tend to modify their environment