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Community Ecology, Population Ecology, and Sustainability Chapter 6.

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Presentation on theme: "Community Ecology, Population Ecology, and Sustainability Chapter 6."— Presentation transcript:

1 Community Ecology, Population Ecology, and Sustainability Chapter 6

2 Why Should We Care about the American Alligator? Overhunted Overhunted Niches Niches Ecosystem services Ecosystem services Keystone species Keystone species Endangered and threatened species Endangered and threatened species Alligator farms Alligator farms Fig. 6-1, p. 108

3 Why Should We Care about the American Alligator? Fig. 6-1, p. 108

4 Community Structure and Species Diversity Physical appearance Physical appearance Edge effects Edge effects Species diversity or richness Species diversity or richness Species abundance or evenness Species abundance or evenness Niche structure Niche structure

5 Fig. 6-2, p. 110 Natural Capital: Types, Sizes, and Stratification of Terrestrial Plants Tropical rain forest Coniferous forest Deciduous forest Thorn forest Thorn scrub Tall-grass prairie Short-grass prairie Desert scrub

6 Species Diversity and Ecological Stability Many different species provide ecological stability Many different species provide ecological stability Some exceptions Some exceptions Minimum threshold of species diversity Minimum threshold of species diversity Many unknowns Many unknowns Net primary productivity (NPP) Net primary productivity (NPP) Essential and nonessential species Essential and nonessential species

7 Types of Species Native Native Nonnative (invasive or alien) Nonnative (invasive or alien) Indicator Indicator Keystone Keystone Foundation Foundation

8 Indicator Species Provide early warnings Provide early warnings Indicator of water quality Indicator of water quality Birds as environmental indicators Birds as environmental indicators Butterflies Butterflies Amphibians Amphibians

9 Amphibians as Indicator Species Environmentally sensitive life cycle Environmentally sensitive life cycle Vulnerable eggs and skin Vulnerable eggs and skin Declining populations Declining populations

10 sperm Eggs Sexual reproduction Fertilized egg development Organ formation Egg hatches Tadpole Tadpole develops into frog Young frog Adult frog (3 years) Fig. 6-3, p. 112 Life Cycle of a Frog

11 Possible Causes of Declining Amphibian Populations Habitat loss and fragmentation Habitat loss and fragmentation Prolonged drought Prolonged drought Pollution Pollution Increases in ultraviolet radiation Increases in ultraviolet radiation Parasites Parasites Overhunting Overhunting Disease Disease Nonnative species Nonnative species

12 Why Should We Care about Vanishing Amphibians? Indicator of environmental health Indicator of environmental health Important ecological roles of amphibians Important ecological roles of amphibians Genetic storehouse for pharmaceuticals Genetic storehouse for pharmaceuticals

13 Keystone Species What is a keystone? What is a keystone? Keystone species play critical ecological roles Keystone species play critical ecological roles Pollination Pollination Top predators Top predators Dung beetles Dung beetles Sharks Sharks

14 Why are Sharks Important? Ecological roles of sharks Ecological roles of sharks Shark misconceptions Shark misconceptions Human deaths and injuries Human deaths and injuries Lightning is more dangerous than sharks Lightning is more dangerous than sharks Shark hunting and shark fins Shark hunting and shark fins Mercury contamination Mercury contamination Medical research Medical research Declining populations Declining populations Hunting bans: effective? Hunting bans: effective?

15 Foundation Species Relationship to keystones species Relationship to keystones species Play important roles in shaping communities Play important roles in shaping communities Elephants Elephants Contributions of bats and birds Contributions of bats and birds

16 Species Interactions Interspecific competition Interspecific competition Predation Predation Parasitism Parasitism Mutualism Mutualism Commensalism Commensalism

17 Species Interactions: Competition Interspecific Competition Interspecific Competition Fundamental niches Fundamental niches Fighting for limited resources Fighting for limited resources Competition from humans Competition from humans

18 Reducing or Avoiding Competition Resource partitioning Resource partitioning Role of natural selection Role of natural selection Specialization and sharing of resources Specialization and sharing of resources Resource partitioning of warblers Resource partitioning of warblers

19 Fig. 6-4, p. 114 Number of individuals Resource use Species 1Species 2 Region of niche overlap Species 1Species 2 Resource Partitioning and Niche Specialization

20 Fig. 6-5, p. 115 Resource Partitioning of Warbler Species

21 Predator and Prey Interactions Carnivores and herbivores Carnivores and herbivores Predators Predators Prey Prey Natural selection and prey populations Natural selection and prey populations

22 How Do Predators Increase Their Chances of Getting a Meal? Speed Speed Senses Senses Camouflage and ambush Camouflage and ambush Chemical warfare (venom) Chemical warfare (venom)

23 Avoiding and Defending Against Predators Escape Escape Senses Senses Armor Armor Camouflage Camouflage Chemical warfare Chemical warfare Warning coloration Warning coloration Mimicry Mimicry Behavior strategies Behavior strategies Safety in numbers Safety in numbers

24 Span worm Bombardier beetle Viceroy butterfly mimics monarch butterfly Foul-tasting monarch butterfly Poison dart frog When touched, the snake caterpillar changes shape to look like the head of a snake Wandering leaf insect Hind wings of io moth resemble eyes of a much larger animal Fig. 6-6, p. 116 How Species Avoid Predators

25 Parasites Parasitism Parasitism Hosts Hosts Inside or outside of hosts Inside or outside of hosts Harmful effects on hosts Harmful effects on hosts Important ecological roles of parasites Important ecological roles of parasites

26 Mutualism Both species benefit Both species benefit Pollination Pollination Benefits include nutrition and protection Benefits include nutrition and protection Mycorrhizae Mycorrhizae Gut inhabitant mutualism Gut inhabitant mutualism

27 Oxpeckers and black rhinocerosClown fish and sea anemone Lack of mycorrhizae fungi on juniper seedlings in sterilized soil Fig. 6-7, p. 117 Examples of Mutualism © 2006 Brooks/Cole - Thomson Mycorrhizae fungi on juniper seedlings in normal soil

28 Commensalism Species interaction that benefits one and has little or no effect on the other Species interaction that benefits one and has little or no effect on the other Example: Small plants growing in shade of larger plants Example: Small plants growing in shade of larger plants Epiphytes Epiphytes

29 Bromeliad Commensalism Fig. 6-8, p. 118

30 Ecological Succession: Communities in Transition What is ecological succession? What is ecological succession? Primary succession Primary succession Secondary succession Secondary succession

31 Fig. 6-9, p. 119 Time Small herbs and shrubs Heath mat Jack pine, black spruce, and aspen Balsam fir, paper birch, and white spruce climax community Exposed rocks Lichens and mosses Primary Ecological Succession

32 Fig. 6-10, p. 120 Annual weeds Perennial weeds and grasses Shrubs and pine seedlings Young pine forest with developing understory of oak and hickory trees Mature oak-hickory forest Secondary Ecological Succession Time

33 How Predictable is Succession? Climax community concept Climax community concept Balance of nature Balance of nature New views of equilibrium in nature New views of equilibrium in nature Unpredictable succession Unpredictable succession Natural struggles Natural struggles

34 Population Dynamics: Factors Affecting Population Size Population change = (births + immigration) – (deaths + emigration) Population change = (births + immigration) – (deaths + emigration) Age structure (stages) Age structure (stages) Age and population stability Age and population stability

35 Limits on Population Growth Biotic potential Biotic potential Intrinsic rate of increase (r) Intrinsic rate of increase (r) No indefinite population growth No indefinite population growth Environmental resistance Environmental resistance Carrying capacity (K) Carrying capacity (K)

36 Exponential and Logistic Population Growth Resources control population growth Resources control population growth Exponential growth Exponential growth Logistic growth Logistic growth

37 Fig. 6-11, p. 121 Carrying capacity (K) Environmental resistance Biotic potential Exponential growth Population Growth Curves Time (t) Population size (N)

38 Fig. 6-12, p. 121 Logistic Growth of Sheep Population Overshoot Carrying Capacity Year Number of sheep (millions) 2.0 1.5 1.0.5 180018251850187519001925

39 When Population Size Exceeds Carrying Capacity Switch to new resources, move or die Switch to new resources, move or die Overshoots Overshoots Reproductive time lag Reproductive time lag Population dieback or crash Population dieback or crash Famines among humans Famines among humans Factors controlling human carrying capacity Factors controlling human carrying capacity

40 Exponential Growth, Overshoot and Population Crash of Reindeer Fig. 6-13, p. 122 Population Overshoots Carrying Capacity Population crashes Carrying capacity Year Number of sheep (millions) 2,000 1,500 1,000 500 0 19101920193019401950

41 Reproductive Patterns r-selected species r-selected species Opportunists (mostly r-selected) Opportunists (mostly r-selected) Environmental impacts on opportunists Environmental impacts on opportunists K-selected species (competitors) K-selected species (competitors) Intermediate and variable reproductive patterns Intermediate and variable reproductive patterns

42 Carrying capacity K species; experience K selection r species; experience r selection K Fig. 6-14, p. 122 Positions of r-selected and K-selected Species on Population Growth Curve Number of individuals Time Number of individuals

43 Fig. 6-15, p. 123 r-selected Opportunists and K-selected Species

44 r-Selected Species Cockroach Dandelion Many small offspring Little or no parental care and protection of offspring Early reproductive age Most offspring die before reaching reproductive age Small adults Adapted to unstable climate and environmental conditions High population growth rate (r) Population size fluctuates wildly above and below carrying capacity (K) Generalist niche Low ability to compete Early successional species Fig. 6-15a, p. 123 r-selected Opportunists and K-selected Species

45 Fewer, larger offspring High parental care and protection of offspring Later reproductive age Most offspring survive to reproductive age Larger adults Adapted to stable climate and environmental conditions Lower population growth rate (r) Population size fairly stable and usually close to carrying capacity (K) Specialist niche High ability to compete Late successional species Elephant Saguaro K-Selected Species Fig. 6-15b, p. 123 r-selected Opportunists and K-selected Species

46 Fig. 6-16, p. 124 PropertyNatural SystemsHuman-Dominated Systems Complexity Energy source Waste production Nutrients Net primary productivity Biologically diverse Renewable solar energy Little, if any Recycled Shared among many species Biologically simplified Mostly nonrenewable fossil fuel energy High Often lost of wasted Used, destroyed, or degraded to support human activities Characteristics of Natural and Human-Dominated Systems

47 Fig. 6-17, p. 125 Reduction of biodiversity Increasing use of the earth's net primary productivity Increasing genetic resistance of pest species and disease causing bacteria Elimination of many natural predators Deliberate or accidental introduction of potentially harmful species into communities Using some renewable resources faster than they can be replenished Interfering with the earth's chemical cycling and energy flow processes Relying mostly on polluting fossil fuels Human Impacts on Ecosystems Natural Capital Degradation Altering Nature to Meet Our Needs

48 Fig. 6-18, p. 126 Four Principles of Sustainability PRINCIPLES OF SUSTAINABILITY Solar Energy Population Control Nutrient Recycling Biodiversity

49 Runs on renewable solar energy. Recycles nutrients and wastes. There is little waste in nature. Uses biodiversity to maintain itself and adapt to new environmental conditions. Controls a species' population size and resource use by interactions with its environment and other species. Rely mostly on renewable solar energy. Prevent and reduce pollution and recycle and reuse resources. Preserve biodiversity by protecting ecosystem services and preventing premature extinction of species. Reduce births and wasteful resource use to prevent environmental overload and depletion and degradation of resources. Fig. 6-19, p. 126 Solutions: Implications of the Principles of Sustainability Solutions Principles of Sustainability How Nature WorksLessons for Us

50 Lessons from Nature We are dependent on the Earth and Sun We are dependent on the Earth and Sun Everything is interdependent with everything else Everything is interdependent with everything else We can never do just one thing We can never do just one thing Earths natural capital must be sustained Earths natural capital must be sustained Precautionary Principle Precautionary Principle Prevention is better than cure Prevention is better than cure Risks must be taken Risks must be taken


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