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Chapter 4 Evolution and Biodiversity. Chapter Overview Questions How do scientists account for the development of life on earth? How do scientists account.

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Presentation on theme: "Chapter 4 Evolution and Biodiversity. Chapter Overview Questions How do scientists account for the development of life on earth? How do scientists account."— Presentation transcript:

1 Chapter 4 Evolution and Biodiversity

2 Chapter Overview Questions How do scientists account for the development of life on earth? How do scientists account for the development of life on earth? What is biological evolution by natural selection, and how can it account for the current diversity of organisms on the earth? What is biological evolution by natural selection, and how can it account for the current diversity of organisms on the earth? How can geologic processes, climate change and catastrophes affect biological evolution? How can geologic processes, climate change and catastrophes affect biological evolution?

3 Chapter Overview Questions (contd) What is an ecological niche, and how does it help a population adapt to changing environmental conditions? What is an ecological niche, and how does it help a population adapt to changing environmental conditions? How do extinction of species and formation of new species affect biodiversity? How do extinction of species and formation of new species affect biodiversity?

4 Chapter Overview Questions (contd) What is the future of evolution, and what role should humans play in this future? What is the future of evolution, and what role should humans play in this future? How did we become such a powerful species in a short time? How did we become such a powerful species in a short time?

5 Review: 4 Principles of Sustainability? 1. 2. 3. 4.

6 Core Case Study: Why Should We Care about the American Alligator? Hunters wiped out population to the point of near extinction. Hunters wiped out population to the point of near extinction. 1967- classified as endangered 1967- classified as endangered 1975- numbers had rebounded 1975- numbers had rebounded 1977- reclassified as threatened 1977- reclassified as threatened Figure 7-1

7 Core Case Study: Why Should We Care about the American Alligator? Alligators have important ecological role. Alligators have important ecological role. Alligators are a keystone species: Alligators are a keystone species: Influence on ecosystem is much greater than their numbers would suggest Influence on ecosystem is much greater than their numbers would suggest Figure 7-1

8 Core Case Study: American Alligator as Keystone Species Dig deep depressions (gator holes). Dig deep depressions (gator holes). Hold water during dry spells, serve as refuges for aquatic life. Hold water during dry spells, serve as refuges for aquatic life. Build nesting mounds. Build nesting mounds. provide nesting and feeding sites for birds. provide nesting and feeding sites for birds. Keeps areas of open water free of vegetation (swimming paths) Keeps areas of open water free of vegetation (swimming paths) Keep gar populations in check Keep gar populations in check

9 Gator Holes

10 Nesting Mounds

11 Keep Waterways Clear

12 Longnose Gar

13 Alligator Gar

14 Core Case Study Earth: The Just-Right, Adaptable Planet Distance from sun Distance from sun Spins Spins Size- molten mantle, retain atmosphere Size- molten mantle, retain atmosphere Stratospheric Ozone Stratospheric Ozone (2 billion years) 21% Oxygen 21% Oxygen (several hundred million years) Biodiversity & Sustainability Biodiversity & Sustainability Temp Temp Figure 4-1

15 Core Case Study Earth: The Just-Right, Adaptable Planet During the 3.7 billion years since life arose, the average surface temperature of the earth has remained within the range of 10-20 o C. During the 3.7 billion years since life arose, the average surface temperature of the earth has remained within the range of 10-20 o C. Figure 4-1

16 Biological Evolution This has led to the variety of species we find on the earth today. This has led to the variety of species we find on the earth today. Figure 4-2

17 Fig. 4-3, p. 84 Modern humans (Homo sapiens sapiens) appear about 2 seconds before midnight Recorded human history begins about 1/4 second before midnight Origin of life (3.6-3.8 billion years ago) Age of mammals Age of reptiles Insects and amphibians invade the land First fossil record of animals Plants begin invading land Evolution and expansion of life

18 How Do We Know Which Organisms Lived in the Past? Our knowledge about past life comes from Our knowledge about past life comes from fossils fossils cores drilled out of buried ice cores drilled out of buried ice analysis of protein similarities analysis of protein similarities DNA & RNA analysis. DNA & RNA analysis. Figure 4-4

19 EVOLUTION, NATURAL SELECTION, AND ADAPTATION Evolution in Seven Words: Genes Mutate, Individuals are Selected, Populations Evolve Genes Mutate, Individuals are Selected, Populations Evolve

20 Natural selection acts on individuals, but evolution occurs in populations Three conditions are necessary for biological evolution: Three conditions are necessary for biological evolution: 1. Genetic variability 2. traits must be heritable 3. trait must lead to differential reproduction. An adaptive trait is any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions. An adaptive trait is any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions.

21 EVOLUTION, NATURAL SELECTION, AND ADAPTATION Biological evolution by natural selection involves the change in a populations genetic makeup through successive generations. Biological evolution by natural selection involves the change in a populations genetic makeup through successive generations. With positive selection pressure, advantageous traits help individuals to survive long enough to have and raise their young. With positive selection pressure, advantageous traits help individuals to survive long enough to have and raise their young. With negative selection pressure, individuals die before they can reproduce. With negative selection pressure, individuals die before they can reproduce.

22 EVOLUTION, NATURAL SELECTION, AND ADAPTATION Advantageous traits originate from genetic variability. Advantageous traits originate from genetic variability. Genetic variability occurs through… Genetic variability occurs through… mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring. mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring. Exposure to mutagens: radioactivity, x rays, certain chemicalsExposure to mutagens: radioactivity, x rays, certain chemicals Random mistakes in DNA duplication, or during RNA transcription and translation.Random mistakes in DNA duplication, or during RNA transcription and translation.

23 Limits on Adaptation through Natural Selection A populations ability to adapt to new environmental conditions through natural selection is limited by its gene pool and how fast it can reproduce. A populations ability to adapt to new environmental conditions through natural selection is limited by its gene pool and how fast it can reproduce. Humans have a relatively slow generation time (decades) and output (# of young) versus some other species. Humans have a relatively slow generation time (decades) and output (# of young) versus some other species.

24 Common Myths about Evolution through Natural Selection Yes: Biological evolution through natural selection is about the most descendants. Yes: Biological evolution through natural selection is about the most descendants. No: (Misunderstandings) No: (Misunderstandings) Survival of the fittest means survival of the biggest, fastest, or strongest. Survival of the fittest means survival of the biggest, fastest, or strongest. Organisms develop certain traits because they need them. Organisms develop certain traits because they need them. Species evolve towards genetic perfection. Species evolve towards genetic perfection.

25 New Species: Hybridization New species can arise through hybridization. New species can arise through hybridization. Occurs when individuals to two distinct species crossbreed to produce a fertile offspring. Occurs when individuals to two distinct species crossbreed to produce a fertile offspring. The red wolf is thought to be a coyote/wolf hybrid

26 New Species: Gene Swapping Some species (mostly microorganisms) can exchange genes without sexual reproduction. Some species (mostly microorganisms) can exchange genes without sexual reproduction. Horizontal gene transfer Horizontal gene transfer

27 BIODIVERSITY

28 Why Should We Care About Biodiversity? Some consider it ethical to care about nature. Some consider it ethical to care about nature. Biodiversity provides us with: Biodiversity provides us with: Natural Resources (food, water, wood, energy, and medicines) Natural Resources (food, water, wood, energy, and medicines) Natural Services (air and water purification, soil fertility, waste disposal, pest control) Natural Services (air and water purification, soil fertility, waste disposal, pest control) Aesthetic pleasure Aesthetic pleasure

29 Biodiversity Loss and Species Extinction: Remember HIPPO H for habitat destruction and degradation H for habitat destruction and degradation I for invasive species I for invasive species P for pollution P for pollution P for human population growth P for human population growth O for overexploitation O for overexploitation

30 ECOLOGICAL NICHES AND ADAPTATION: Coastal Georgia Smooth cordgrass, Spartina alterniflora, Can grow in fresh water… …but it doesnt in the wild. Why not?

31 ECOLOGICAL NICHES AND ADAPTATION Each species in an ecosystem has a specific role or way of life. Each species in an ecosystem has a specific role or way of life. Fundamental niche: the full potential range of physical, chemical, and biological conditions and resources a species could theoretically use. Fundamental niche: the full potential range of physical, chemical, and biological conditions and resources a species could theoretically use. Realized niche: to survive and avoid competition, a species usually occupies only part of its fundamental niche. Realized niche: to survive and avoid competition, a species usually occupies only part of its fundamental niche.

32 Species Diversity and Niche Structure: Different Species Playing Different Roles Biological communities differ in the types and numbers of species they contain and the ecological roles those species play. Biological communities differ in the types and numbers of species they contain and the ecological roles those species play. Species diversity has 2 components: Species diversity has 2 components: species richness the number of different species the ecosystem contains species richness the number of different species the ecosystem contains species evenness the abundance of individuals within each of those species. species evenness the abundance of individuals within each of those species.

33 Species Diversity and Niche Structure Niche structure: how many potential ecological niches occur, how they resemble or differ, and how the species occupying different niches interact. Niche structure: how many potential ecological niches occur, how they resemble or differ, and how the species occupying different niches interact. Geographic location: species diversity is highest in the tropics and declines as we move from the equator toward the poles. Geographic location: species diversity is highest in the tropics and declines as we move from the equator toward the poles.

34 TYPES OF SPECIES Native, nonnative, indicator, keystone, and foundation species play different ecological roles in communities. Native, nonnative, indicator, keystone, and foundation species play different ecological roles in communities. Native: those that normally live and thrive in a particular community. Native: those that normally live and thrive in a particular community. Nonnative species a.k.a. invasive species: those that migrate, deliberately or accidentally introduced into a community. Nonnative species a.k.a. invasive species: those that migrate, deliberately or accidentally introduced into a community.

35 Indicator Species: Biological Smoke Alarms Species that serve as early warnings of damage to a community or an ecosystem. Species that serve as early warnings of damage to a community or an ecosystem. Canary in a coal mine Canary in a coal mine Presence or absence of trout species because they are sensitive to temperature and oxygen levels. Presence or absence of trout species because they are sensitive to temperature and oxygen levels. Birds- require a range of habitat Birds- require a range of habitat Lichens- stay in one place and absorb from the environment Lichens- stay in one place and absorb from the environment Amphibians- vulnerable at any part of life cycle Amphibians- vulnerable at any part of life cycle

36 Case Study: Why are Amphibians Vanishing? Frogs serve as indicator species because different parts of their life cycles can be easily disturbed. Frogs serve as indicator species because different parts of their life cycles can be easily disturbed. Next

37 Fig. 7-3, p. 147 Young frog Adult frog (3 years) Sperm Sexual Reproduction Eggs Fertilized egg development Organ formation Egg hatches Tadpole Tadpole develops into frog

38 Case Study: Why are Amphibians Vanishing? Habitat loss and fragmentation. Habitat loss and fragmentation. Prolonged drought. Prolonged drought. Increases in ultraviolet radiation. Increases in ultraviolet radiation. Parasites. Parasites. Viral and Fungal diseases. Viral and Fungal diseases. Overhunting. Overhunting. Air OR water pollution Air OR water pollution Natural immigration or deliberate introduction of nonnative predators and competitors. Natural immigration or deliberate introduction of nonnative predators and competitors.

39 Keystone Species: Major Players Keystone species help determine the types and numbers of other species in a community thereby helping to sustain it. Keystone species help determine the types and numbers of other species in a community thereby helping to sustain it. Figures 7-4 and 7-5

40 Foundation Species: Other Major Players Expansion of keystone species category. Expansion of keystone species category. Foundation species can create and enhance the physical habitats to benefit other species in a community. Foundation species can create and enhance the physical habitats to benefit other species in a community. Elephants push over, break, or uproot trees, creating forest openings promoting grass growth for other species to utilize. Elephants push over, break, or uproot trees, creating forest openings promoting grass growth for other species to utilize. Alligators making gator holes Alligators making gator holes

41 Generalist and Specialist Species: Broad and Narrow Niches Generalist species tolerate a wide range of conditions. Generalist species tolerate a wide range of conditions. Specialist species can only tolerate a narrow range of conditions. Exp: tiger salamander, giant panda Specialist species can only tolerate a narrow range of conditions. Exp: tiger salamander, giant panda Figure 4-7

42 Fig. 4-7, p. 91 Generalist species with a broad niche Number of individuals Resource use Specialist species with a narrow niche Niche separation Niche breadth Region of niche overlap

43 SPOTLIGHT Cockroaches: Natures Ultimate Survivors 350 million years old 350 million years old 3,500 different species 3,500 different species Ultimate generalist Ultimate generalist Can eat almost anything. Can eat almost anything. Can live and breed almost anywhere. Can live and breed almost anywhere. Can withstand massive radiation. Can withstand massive radiation. Figure 4-A

44 Specialized Feeding Niches Resource partitioning reduces competition and allows sharing of limited resources. Resource partitioning reduces competition and allows sharing of limited resources. Figure 4-8

45 Fig. 4-8, pp. 90-91 Piping plover feeds on insects and tiny crustaceans on sandy beaches (Birds not drawn to scale) Black skimmer seizes small fish at water surface Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans,and aquatic vegetation 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 Louisiana heron wades into water to seize small fish Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Knot (a sandpiper) picks up worms and small crustaceans left by receding tide Herring gull is a tireless scavenger Ruddy turnstone searches under shells and pebbles for small invertebrates

46 Evolutionary Divergence: Darwins Finches Each species has a beak specialized to take advantage of certain types of food resource. Each species has a beak specialized to take advantage of certain types of food resource. Next

47 Fig. 4-9, p. 91 Maui Parrotbill Fruit and seed eaters Insect and nectar eaters Kuai Akialaoa Amakihi Crested Honeycreeper Apapane Akiapolaau Unknown finch ancestor Greater Koa-finch Kona Grosbeak

48 NATURAL SELECTION: DRIVEN BY GEOLOGIC PROCESSES, CLIMATE CHANGE, & CATASTROPHES The movement of solid tectonic plates making up the earths surface, volcanic eruptions, and earthquakes can wipe out existing species and help form new ones. The movement of solid tectonic plates making up the earths surface, volcanic eruptions, and earthquakes can wipe out existing species and help form new ones. The locations of continents and oceanic basins influence climate. The locations of continents and oceanic basins influence climate. The movement of continents have allowed species to move. The movement of continents have allowed species to move.

49 Fig. 4-5, p. 88 135 million years ago Present 65 million years ago 225 million years ago

50 Climate Change and Natural Selection Changes in climate throughout the earths history have shifted where plants and animals can live. Changes in climate throughout the earths history have shifted where plants and animals can live. Next

51 Fig. 4-6, p. 89 Land above sea level 18,000 years before present Northern Hemisphere Ice coverage Modern day (August) Note: Modern sea ice coverage represents summer months Legend Continental ice Sea ice

52 SPECIATION, EXTINCTION, AND BIODIVERSITY Speciation: A new species can arise when member of a population become isolated for a long period of time. Speciation: A new species can arise when member of a population become isolated for a long period of time. Due to natural selection over time, the genetic makeup changes, preventing them from producing fertile offspring with the original population if reunited. Due to natural selection over time, the genetic makeup changes, preventing them from producing fertile offspring with the original population if reunited.

53 Catastrophes and Natural Selection Asteroids and meteorites hitting the earth and upheavals of the earth from geologic processes have wiped out large numbers of species and created evolutionary opportunities by natural selection of new species. Asteroids and meteorites hitting the earth and upheavals of the earth from geologic processes have wiped out large numbers of species and created evolutionary opportunities by natural selection of new species.

54 Geographic Isolation… …can lead to reproductive isolation, which leads to divergence of gene pools and speciation. …can lead to reproductive isolation, which leads to divergence of gene pools and speciation. Figure 4-10

55 Fig. 4-10, p. 92 Different environmental conditions lead to different selective pressures and evolution into two different species. Southern Population Northern population Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Adapted to cold through heavier fur,short ears, short legs,short nose. White fur matches snow for camouflage. Gray Fox Arctic Fox Spreads northward and southward and separates Early fox Population

56 Extinction: Lights Out Extinction occurs when the population cannot adapt to changing environmental conditions. Extinction occurs when the population cannot adapt to changing environmental conditions. The golden toad of Costa Ricas Monteverde cloud forest has become extinct because of changes in climate. The golden toad of Costa Ricas Monteverde cloud forest has become extinct because of changes in climate. Figure 4-11

57 Categorizing Extinction Rates Biologists estimate that 99.9% of all the species that ever existed are now extinct. Biologists estimate that 99.9% of all the species that ever existed are now extinct. Background extinction- a certain number of species disappearing at a slow rate due to changes of local environmental conditions Background extinction- a certain number of species disappearing at a slow rate due to changes of local environmental conditions Estimate: 1-5 species per million per yearEstimate: 1-5 species per million per year Mass depletion- rates of extinction above background level but not high enough to be considered a mass extinction. Mass depletion- rates of extinction above background level but not high enough to be considered a mass extinction. Mass extinction- a significant rise in extinction rate above background level. Mass extinction- a significant rise in extinction rate above background level.

58 Effects of Humans on Biodiversity The scientific consensus is that human activities are decreasing the earths biodiversity. The scientific consensus is that human activities are decreasing the earths biodiversity. Figure 4-13

59 Fig. 4-13, p. 94 Marine organisms Terrestrial organisms Number of families Millions of years ago Quaternary Tertiary Pre-cambrian Cambrian Ordovician Silurian Devonian Carboniferous Jurassic Devonian Permian Cretaceous

60 Fig. 4-12, p. 93 Tertiary Bar width represents relative number of living species EraPeriod Species and families experiencing mass extinction Millions of years ago Ordovician: 50% of animal families, including many trilobites. Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites. 500 345 Cambrian Ordovician Silurian Devonian Extinction Paleozoic Mesozoic Cenozoic Triassic: 35% of animal families, including many reptiles and marine mollusks. Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites. Carboniferous Permian Current extinction crisis caused by human activities. Many species are expected to become extinct within the next 50–100 years. Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including many foraminiferans and mollusks. Extinction Triassic Jurassic Cretaceous 250 180 65 Extinction QuaternaryToday

61 GENETIC ENGINEERING AND THE FUTURE OF EVOLUTION Figure 4-15 We have used genetic engineering to transfer genes from one species to another (gene splicing) We have used genetic engineering to transfer genes from one species to another (gene splicing) Takes half the time and costs less than crossbreeding. Takes half the time and costs less than crossbreeding. We have used artificial selection to change the genetic characteristics of populations with similar genes through selective breeding. We have used artificial selection to change the genetic characteristics of populations with similar genes through selective breeding.

62 Genetic Engineering: Genetically Modified Organisms (GMO) GMOs use recombinant DNA GMOs use recombinant DNA genes or portions of genes from different organisms. genes or portions of genes from different organisms. Figure 4-14

63 Case Study: Species Diversity on Islands MacArthur and Wilson proposed the species equilibrium model a.k.a. theory of island biogeography in the 1960s. MacArthur and Wilson proposed the species equilibrium model a.k.a. theory of island biogeography in the 1960s. Model projects that at some point the rates of immigration and extinction should reach an equilibrium based on: Model projects that at some point the rates of immigration and extinction should reach an equilibrium based on: Island size Island size Distance to nearest mainland Distance to nearest mainland

64 THE FUTURE OF EVOLUTION Biologists are learning to rebuild organisms from their cell components and to clone organisms. Biologists are learning to rebuild organisms from their cell components and to clone organisms. Cloning has lead to high miscarriage rates, rapid aging, organ defects. Cloning has lead to high miscarriage rates, rapid aging, organ defects. Genetic engineering can help improve human condition, but results are not always predictable. Genetic engineering can help improve human condition, but results are not always predictable. Currently: We do not know where the new gene will be located in the DNA molecules structure and how that will affect the organism. Currently: We do not know where the new gene will be located in the DNA molecules structure and how that will affect the organism.

65 Biopharming Biopharming is when humans use genetically engineered organisms for the production of consumables such as Biopharming is when humans use genetically engineered organisms for the production of consumables such as Drugs Drugs Chemicals Chemicals Human body parts Human body parts Which one of these have we not yet mastered? Which one of these have we not yet mastered?

66 Controversy Over Genetic Engineering There are a number of privacy, ethical, legal and environmental issues. There are a number of privacy, ethical, legal and environmental issues. Should genetic engineering and development be regulated? Should genetic engineering and development be regulated? What are the long-term environmental consequences? What are the long-term environmental consequences?

67 Case Study: How Did We Become Such a Powerful Species so Quickly? Compared to other species, we lack: strength, speed, agility. strength, speed, agility. weapons (claws, fangs), protection (shell). weapons (claws, fangs), protection (shell). poor hearing and vision. poor hearing and vision. We have thrived as a species because of our: opposable thumbsopposable thumbs ability to walk uprightability to walk upright complex brains (problem solving).complex brains (problem solving).

68 Ch 4 Final Thoughts Microevolution- Traits changing in a species (e.g.color, fur type, etc.) Microevolution- Traits changing in a species (e.g.color, fur type, etc.) Industrial Melanism Industrial Melanism in pepper moths: in pepper moths: Macroevolution- The development of new species Macroevolution- The development of new species

69 Ch 4 Final Thoughts Gradualism- species change slowly over time at a steady rate of change (Darwin was wrong about this) Gradualism- species change slowly over time at a steady rate of change (Darwin was wrong about this) Punctuated Equilibrium- Long periods of stability punctuated by peiods of rapid change, initiated by changes in the environment (evolutionary biologist Stephen Jay Gould) Punctuated Equilibrium- Long periods of stability punctuated by peiods of rapid change, initiated by changes in the environment (evolutionary biologist Stephen Jay Gould) # of species Time # of species Time

70 Ch 4 Final Thoughts Natural Selection happens to individuals, and leads to differential reproduction (think about the wooly worms lab) Natural Selection happens to individuals, and leads to differential reproduction (think about the wooly worms lab) Evolution happens to a population over time, and is ultimately understood as changes in gene frequencies within that population. Evolution happens to a population over time, and is ultimately understood as changes in gene frequencies within that population. Leads to microevolution in the short term Leads to microevolution in the short term Leads to macroevolution in the long term Leads to macroevolution in the long term

71 Genetic Engineering: Genetically Modified Organisms (GMO) GMOs use recombinant DNA GMOs use recombinant DNA genes or portions of genes from different organisms. genes or portions of genes from different organisms. Figure 4-14

72 Fig. 4-14, p. 95 Insert modified plasmid into E. coli Phase 1 Make Modified Gene Cell Extract DNA E. coli Gene of interest DNA Identify and extract gene with desired trait Genetically modified plasmid Identify and remove portion of DNA with desired trait Remove plasmid from DNA of E. coli Plasmid Extract Plasmid Grow in tissue culture to make copies Insert extracted (step 2) into plasmid (step 3)

73 Fig. 4-14, p. 95 Plant cell Phase 2 Make Transgenic Cell Transfer plasmid to surface of microscopic metal particle Use gene gun to inject DNA into plant cell Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell Transfer plasmid copies to a carrier agrobacterium Nucleus E. Coli A. tumefaciens (agrobacterium) Foreign DNA Host DNA

74 Fig. 4-14, p. 95 Cell division of transgenic cells Phase 3 Grow Genetically Engineered Plant Transfer to soil Transgenic plants with new traits Transgenic cell from Phase 2 Culture cells to form plantlets

75 Fig. 4-14, p. 95 Phase 3 Grow Genetically Engineered Plant Transgenic cell from Phase 2 Cell division of transgenic cells Culture cells to form plantlets Transgenic plants with new traits Transfer to soil Stepped Art


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