1. Biodiversity and Evolution
Chapter 4

2. Core Case Study: Why Should We Care about the American Alligator?
Largest reptile in North America
1930s – 1960s Hunters and poachers nearly wiped out entire population in LA and FL
Importance of gator holes and nesting mounds
freshwater supply; aquatic refuge; nesting & feeding sites; population control
1967: endangered species
1977: comeback, threatened species
Today it is considered recovered
Swamp People — The Season Begins — History.com Videos

3. 4-1 What Is Biodiversity and Why Is It Important?
Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth.

4. Biodiversity Is a Crucial Part of the Earth’s Natural Capital
Species diversity
Genetic Diversity
Ecosystem diversity
Each ecosystem a storehouse of genetic & species diversity
Functional diversity – the variety of processes taking place within ecosystems
Occurs as species interact in food webs

5. Supplies us with wood, fibers, energy, medicines ($$$$$)
Biodiversity is vital part of Earth’s Natural Capital and provides a variety of ecological services:
Supplies us with wood, fibers, energy, medicines ($$$$$)
Preserves quality of air and water
Maintains soil fertility
Helps dispose of wastes
Population control of pests
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6. Natural Capital: Major Components of the Earth’s Biodiversity

7. 4-2 Where Do Species Come From?
Concept 4-2A The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations.
Concept 4-2B Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

8. Biological Evolution by Natural Selection Explains How Life Changes over Time
Charles Darwin
Alfred Russel Wallace
Members of a population have genetically based traits that enhance their ability to survive & reproduce
Tree of Life

9. Six Major Kingdoms of Species as a Result of Natural Selection

10. The Fossil Record Tells Much of the Story of Evolution
Fossils
Physical evidence of ancient organisms
Reveal what their internal structures looked like
Fossil record is incomplete: why?

11. Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era

12. The Genetic Makeup of a Population Can Change
Populations evolve (not individuals) by becoming genetically different
Genetic variations
First step in biological evolution
Occurs through mutations in reproductive cells
Mutations due to: random copying errors or exposure to external agents

13. Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
Natural selection: acts on individuals
Second step in biological evolution
Some individuals have traits that enhance ability to survive
Adaptation may lead to differential reproduction (leave more offspring than those w/o the trait)
Genetic resistance – ability of individuals to tolerate a chemical designed to kill it
Genes mutate, individuals are selected, and populations evolve that are better adapted to survive & reproduce under existing environmental conditions
When environmental conditions change, populations
Adapt
Migrate
Become extinct

14. A group of bacteria, including genetically resistant ones, are
exposed to an antibiotic
Normal bacterium
Resistant bacterium
Eventually the resistant strain
replaces the strain affected by
the antibiotic
The genetically resistant bacteria
start multiplying
Most of the normal bacteria die
Figure 4.5
Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all but those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace the nonresistant bacteria.
Stepped Art
Fig. 4-5, p. 83

15. Case Study: How Did Humans Become Such a Powerful Species?
Three human adaptations
Strong opposable thumbs
Walk upright
Complex brain

16. Adaptation through Natural Selection Has Limits
Genetic change must precede change in the environmental conditions – traits must already be there
Reproductive capacity
Species that reproduce rapidly adapt to env changes quickly (100s of years)
Species that reproduce slowly adapt slowly (thousands to millions of years)

17. Three Common Myths about Evolution through Natural Selection
“Survival of the fittest” is not “survival of the strongest”
fitness is a measure of reproductive success
Organisms do not develop traits out of need or want
No grand plan of nature for perfect adaptation
It’s a random branching process that results in a great variety of species

18. Animation: Change in moth population

19. 4-3 How Do Geological Processes and Climate Change Affect Evolution?
Concept 4-3 Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.

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

21. 225 million years ago 135 million years ago 65 million years ago
Present
Figure 4.6
Over millions of years, the earth’s continents have moved very slowly on several gigantic tectonic plates. This process plays a role in the extinction of species, as land areas split apart, and also in the rise of new species when isolated land areas combine. Rock and fossil evidence indicates that 200–250 million years ago, all of the earth’s present-day continents were locked together in a supercontinent called Pangaea (top left). About 180 million years ago, Pangaea began splitting apart as the earth’s tectonic plates separated, eventually resulting in today’s locations of the continents (bottom right). Question: How might an area of land splitting apart cause the extinction of a species?
Stepped Art
Fig. 4-6, p. 85

22. Climate Change and Catastrophes Affect Natural Selection
Ice ages followed by warming temperatures
Collisions between the earth and large asteroids
New species
Extinction
Shifting of ecosystems; destruction of ecosystems; opportunities for species

23. Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years
Figure 4.7
Changes in ice coverage in the northern hemisphere during the past 18,000 years. Question: What are two characteristics of an animal and two characteristics of a plant that natural selection would have favored as these ice sheets (left) advanced? (Data from the National Oceanic and Atmospheric Administration)

24. Science Focus: Earth Is Just Right for Life to Thrive
Certain temperature range
Dependence on water
Rotation on its axis
Revolution around the sun
Enough gravitational mass

25. Animation: Continental drift

26. 4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
Concept 4-4A As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth’s biodiversity.
Concept 4-4B Human activities can decrease biodiversity by causing the premature extinction of species and by destroying or degrading habitats needed for the development of new species.

27. How Do New Species Evolve?
Geographic isolation – certain groups of same population become physically isolated for a long period of time
Migrate for food
Physical barriers (mtn, road, stream)
Volcanic eruption or earthquake
Wind or flowing water
Reproductive isolation – mutation & change by natural selection operate independently in gene pools of geographically isolated populations

28. Geographic Isolation Can Lead to Reproductive Isolation
Figure 4.8
Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation

29. Extinction is Forever Extinction Endemic species
Only found in one or very few locations
Particularly vulnerable

30. Golden Toad of Costa Rica, Extinct

31. Extinction Can Affect One Species or Many Species at a Time
Background extinction – species disappear at a low rate (1-5 species for each million species on Earth)
Mass extinction – significant rise in extinction rates
Large scale event
25-70% of species wiped out in geological period lasting up to 5 million years
Fossil record indicates 5 mass extinction events (20-60 million years apart)
Extinction a natural process & provides opportunities for evolution of new species

32. http://www. pbs. org/wgbh/evolution/library/03/2/image_pop/l_032_04

33. Science Focus: We Have Two Ways to Change the Genetic Traits of Populations
Artificial selection
Genetic engineering, gene splicing
Consider
Ethics
Morals
Privacy issues
Harmful effects

34. Genetically Engineered Mice

35. Animation: Speciation on an archipelago

36. Animation: Transferring genes into plants

37. 4-5 What Is Species Diversity and Why Is It Important?
Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.

38. Species Diversity: Variety, Abundance of Species in a Particular Place
Species richness - # of different species
Species evenness - # of individuals within a species
Ex: Coral Reef – high species richness but low species evenness
Diversity varies with geographical location
Most species-rich communities
Tropical rain forests
Coral reefs
Ocean bottom zone
Large tropical lakes

39. Variations in Species Richness and Species Evenness

40. Science Focus: Species Richness on Islands
Species equilibrium model, theory of island biogeography
Rate of new species immigrating should balance with the rate of species extinction
Island size and distance from the mainland need to be considered

41. Species-Rich Ecosystems Tend to Be Productive and Sustainable
Species richness seems to increase productivity and stability or sustainability
How much species richness is needed is debatable

42. 4-6 What Roles Do Species Play in Ecosystems?
Concept 4-6A Each species plays a specific ecological role called its niche.
Concept 4-6B Any given species may play one or more of five important roles—native, nonnative, indicator, keystone, or foundation roles—in a particular ecosystem.

43. Each Species Plays a Unique Role in Its Ecosystem
Ecological niche, niche
Pattern of living
Generalist species
Broad niche
Specialist species
Narrow niche

44. Specialist Species and Generalist Species Niches

45. Case Study: Cockroaches: Nature’s Ultimate Survivors
Generalists
High reproductive rates
Giant panda and tiger salamanders
Specialists
Low reproductive rates

46. Specialized Feeding Niches of Various Bird Species in a Coastal Wetland

47. Niches Can Be Occupied by Native and Nonnative Species
Nonnative species; invasive, alien, or exotic species
May spread rapidly
Not all are villains – cattle, chickens, crops

48. Indicator Species Serve as Biological Smoke Alarms
Indicator species – provide early warning of damage to an ecosystem
Can monitor environmental quality
Trout
Birds
Butterflies
Frogs
Canaries in the coal mine

49. Case Study: Why Are Amphibians Vanishing? (1)
Habitat loss and fragmentation
Prolonged drought
Pollution
Increase in UV radiation
Parasites
Viral and fungal diseases
Climate change
Overhunting
Nonnative predators and competitors

50. Case Study: Why Are Amphibians Vanishing? (2)
Importance of amphibians
Sensitive biological indicators of environmental changes
Adult amphibians
Important ecological roles in biological communities – major insect predators
Genetic storehouse of pharmaceutical products waiting to be discovered
Anitbiotics
Painkillers
Burn treatment

51. Life Cycle of a Frog Figure 4.14
Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful factors at different points in their life cycle. Such factors include habitat loss, drought, pollution, increased ultraviolet radiation, parasitism, disease, overhunting by humans, and nonnative predators and competitors.

52. Keystone, Foundation Species Determine Structure, Function of Their Ecosystems
Keystone species – play large role in types & abundance of other species in ecosystems
Pollinators – bees, butterflies, bats
Top predator – alligator, lion, wolf, leopard
Foundation species
Create or enhance their habitats, which benefit others
Elephants – push over trees creating forest openings in grasslands and woodlands – promotes grasses for grazers
Beavers – create wetlands

53. Case Study: Why Should We Protect Sharks?
Keystone species
Eat dead and dying fish in the ocean
Strong immune systems
Wounds do not get infected
Almost never get cancer
Could help humans if we understood their immune system
Most vulnerable and least protected animals on earth
Populations have been decimated – 11 of world’s open ocean species endangered; 81 species threatened with extinction
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