Communities & Ecosytems

Communities & Ecosytems
Chapter 54-55

You Need to Know The difference between a fundamental niche and a realized niche. The role of competitive exclusion in interspecific competition. The symbiotic relationships of parasitism, mutualism, and commensalism The impact of keystone species on community structure The difference between primary and secondary succession

What is a Community? It’s Niche
Community: A collection of populations that interact with one another in a given area. Within a community, different populations will play different roles. What do we call the role a population plays in its community? It’s Niche

What is the difference between the prefix inter and intra?
Inter- means between different groups. Intra- means within the same group. Intraspecific competition for resources are examples of density dependent limiting factors for a single population.

Why are Community Interactions Important?
Community interactions can be classified by whether they help, harm, or have no effect on the species involved Ecologists call relationships between species in a community interspecific interactions Examples include: competition predation herbivory symbiosis (parasitism, mutualism, and commensalism) facilitation

Why are Community Interactions Important?
Interspecific interactions can affect the survival and reproduction of each species, and the effects can be summarized as positive (+), negative (–), or no effect (0)

An example of interspecific interactions:
the “carrier crab” carries a sea urchin on its back for protection against predators

Interspecific Competition
Interspecific competition (–/– interaction) Occurs when species compete for a resource in short supply Two different species compete for the same limited resource Squirrels and black bears compete for acorns

Competitive Exclusion
Strong competition can lead to competitive exclusion, local elimination of a competing species The competitive exclusion principle states that two species competing for the same limiting resources cannot coexist in the same place What will decide which species will win out?

Niche Ecological niche (ecological role)
Sum of an organism’s use of biotic and abiotic resources Interspecific competition occurs when the niches of two populations overlap Competition lowers the carrying capacity of competing populations

Fundamental vs. Realized Niche?
The potential niche a species can occupy. The actual niche a species occupies

Niche Ecologically similar species can coexist in a community if there are one or more significant differences in their niches Resource partitioning is differentiation of ecological niches, enabling similar species to coexist in a community

A. distichus perches on fence posts and other sunny surfaces. A. insolitus usually perches on shady branches. A. ricordii A. insolitus A. aliniger A. christophei A. distichus A. cybotes A. etheridgei

Mutualism (+/+) When two organisms interact closely in a way that benefits both species. Honeybees have a mutualistic relationship with flowers. How is this so?

Interspecific interactions: Mutualism
Reef-building corals require mutualism Photosynthetic dinoflagellates Live in the cells of each coral polyp Produce sugars used by the polyps Provide at least half of the energy used by the coral animals

Remember Nemo?

Interspecific interactions: Predation
Predation (+/– interaction) refers to interaction where one species, the predator, kills and eats the other, the prey Some feeding adaptations of predators are claws, teeth, fangs, stingers, and poison

Interspecific interactions: Predation (contd.)
Predation benefits the predator but kills the prey Prey adapt using protective strategies Camouflage Mechanical defenses Chemical defenses

A harmless species mimics a harmful one.
Figure 54.5 (b) Aposematic coloration Poison dart frog Cryptic coloration Canyon tree frog (c) Batesian mimicry: A harmless species mimics a harmful one. (d) Müllerian mimicry: Two unpalatable species mimic each other. Hawkmoth larva Cuckoo bee Yellow jacket Green parrot snake Figure 54.5 Examples of defensive coloration in animals.

Camouflage Figure 37.5A Camouflage: a gray tree frog on bark.

Poison Figure 37.5B Chemical defenses: the poison-arrow frog.

Interspecific Interactions: Herbivory
Herbivory (+/–) (type of predation) refers to an interaction in which an herbivore eats parts of a plant or alga It has led to evolution of plant mechanical and chemical defenses and adaptations by herbivores

Figure 54.6 Figure 54.6 A West Indies manatee (Trichechus manatus) in Florida.

Interspecific Interactions: Herbivory
Herbivory is not usually fatal to the plant Plants must expend energy to replace the loss Plants have numerous defenses against herbivores Spines and thorns Chemical toxins Herbivores must adapt to the defenses created by their food.

Coevolution Coevolution: A series of reciprocal evolutionary adaptations in two species. A change in one species acts as a new selective force on another Poison-resistant caterpillars seem to be a strong selective force for Passiflora plants

Heliconius, caterpillar has enzymes to break down poison of Passiflora (plant).
The Plant has since adapted sugar-deposits to mimic butterfly eggs. The Heliconius butterfly will not lay eggs on a leaf with another butterflies eggs already attached. Eggs Figure 37.6 Coevolution: Heliconius and the passionflower vine (Passiflora). Sugar deposits

What affect do Parasites & Pathogens have on Communities

Parasites In parasitism (+/– interaction), one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process Parasites that live within the body of their host are called endoparasites Such as nematodes and tapeworms Parasites that live on the external surface of a host are ectoparasites Such as mosquitoes and ticks

Parasite examples Ticks Tapeworms Liver flukes

What affect do Parasites & Pathogens have on Communities
Pathogens are disease-causing parasites Pathogens can be bacteria, viruses (non-living), fungi, or protists Non-native pathogens can have rapid and dramatic impacts American chestnut devastated by chestnut blight protist A fungus-like pathogen currently causing sudden oak death on the West Coast Non-native pathogens can cause a decline of the ecosystem

Alphids parasitizing a plant

What do you think the suffix ‘trophic’ refers to?
What adaptations have predators & prey evolved in order to help survive? Explain coevolution. Explain using examples why non-native parasitism, or pathogens, are typically dramatic for an ecosystem. Explain and give an example of an autotrophic organism. Explain and give an example of an heterotrophic organism. What do you think the suffix ‘trophic’ refers to?

On the sheet of paper you were supposed to grab on your way in.
Create a food chain that spans 4 trophic levels. Be sure to start with a producer.

How does Trophic Structure play into Community Dynamics?
A pattern of feeding relationships consisting of several different levels Food chain Sequence of food transfer up the trophic levels

Producers Support all other trophic levels Autotrophs Photosynthetic producers Plants on land Cyanobacteria in water

Producers Where does the energy for life processes come from?

Producers Sunlight Producers
Without a constant input of energy, living systems cannot function. What do you think is the main energy source for life on Earth? Sunlight

Producers Autotrophs What are these organisms called?
Only plants, some algae, and certain bacteria can capture energy from sunlight and use that energy to produce food. What are these organisms called? Autotrophs

Producers In a few ecosystems, some organisms obtain energy from a source other than sunlight.

Producers Life Without Light
Some autotrophs can produce food in the absence of light. Chemosynthetic bacteria are important in deep sea ecosystems.

Producers Sunlight is the main energy source for life on Earth. Some types of organisms rely on the energy stored in inorganic chemical compounds. Other autotrophs, such as sulfur bacteria, use the energy stored in chemical bonds for chemosynthesis. In both cases, energy-rich carbohydrates are produced.

Producers Some chemosynthetic bacteria live in very remote places on Earth, such as volcanic vents on the deep-ocean floor and hot springs. Others live in more common places, such as tidal marshes along the coast.

Consumers Consumers heterotrophs
Organisms that rely on other organisms for their energy and food supply are called ________________. Heterotrophs are also called consumers. heterotrophs

Consumers There are many different types of heterotrophs.
____________ eat plants. ____________ eat animals. ____________ eat both plants and animals. ____________ feed on plant and animal remains and other dead matter. _____________, like bacteria and fungi, break down organic matter. Herbivores Carnivores Omnivores Scavengers Decomposers

Consumers Heterotrophs Primary consumers: Eat Producers Secondary consumers Tertiary consumers Quaternary consumers Detritivores and decomposers: Derive energy from dead matter and wastes

A terrestrial food chain An aquatic food chain
Figure 37.8 Two food chains. Plant Phytoplankton Producers A terrestrial food chain An aquatic food chain

Figure 37.8 Two food chains. Grasshopper Primary consumers Zooplankton Plant Phytoplankton Producers A terrestrial food chain An aquatic food chain

Secondary consumers Primary consumers
Mouse Secondary consumers Herring Figure 37.8 Two food chains. Grasshopper Primary consumers Zooplankton Plant Phytoplankton Producers A terrestrial food chain An aquatic food chain

Tertiary consumers Secondary consumers Primary consumers
Snake Tertiary consumers Tuna Mouse Secondary consumers Herring Figure 37.8 Two food chains. Grasshopper Primary consumers Zooplankton Plant Phytoplankton Producers A terrestrial food chain An aquatic food chain

Trophic level Quaternary consumers Hawk Killer whale Snake Tertiary consumers Tuna Mouse Secondary consumers Herring Figure 37.8 Two food chains. Grasshopper Primary consumers Zooplankton Plant Phytoplankton Producers A terrestrial food chain An aquatic food chain

Decomposition Detritivores, such as scavengers, eat detritus, or dead organic material. Decomposers, mainly fungi & prokaryotes, secrete enzymes to digest molecules in organic material and convert them to inorganic forms. Think of the Great Circle Of Life.

Web of Life

Food chains interconnect, forming food webs
Food web A network of interconnecting food chains Student Misconceptions and Concerns 1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems. Teaching Tips 1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights. 2. Students have often had prior exposure to the concepts of food webs and food chains. Present a food web (perhaps Figure 37.9) to your class and challenge them to predict the consequences of a decrease or increase in the population of one of the organisms. This activity can help students understand how difficult it is to make precise predictions about these complex systems. Copyright © 2009 Pearson Education, Inc.

Quaternary, tertiary, and secondary consumers Tertiary and secondary
primary consumers Primary consumers Figure 37.9 A food web. Producers (plants)

Feeding Relationships
This food web shows some of the feeding relationships in a salt-marsh community. This illustration of a food web shows some of the feeding relationships in a salt marsh.

Diversity of Species Species diversity is the variety of organisms that make up the community It has two components: Species richness is the total number of different species in the community Relative abundance is the proportion each species represents of the total individuals in the community Plant species diversity in a community affects the animals Species diversity has consequences for pathogens

Figure 54.10 Compare and contrast the species richness and species abundance for communities 1 & 2. A B C D Community 1 Community 2 Figure Which forest is more diverse? A: 25% B: 25% C: 25% D: 25% A: 80% B: 5% C: 5% D: 10%

Species Diversity Communities with higher diversity are: More productive and more stable in their productivity Better able to withstand and recover from environmental stresses More resistant to invasive species, organisms that become established outside their native range

Quick Check Which would you expect to have higher species diversity, a well-maintained lawn, or one that is poorly maintained? Explain. The poorly maintained lawn would have higher species diversity. A well-maintained lawn should have low species diversity. While a lawn that is cared for may not be a perfect monoculture, any weeds that are present would have low relative abundance.

Review Explain competitive exclusion
Difference between a fundamental and realized niche. When 2 species are competing for a resource, the species with a slight advantage will eliminate the other. Fundamental niche is the niche potentially occupied by the species. The realized niche is the portion of the fundamental niche the species actually occupies.

Review What is symbiosis?
A +/- symbiotic interaction in which one organism derives nourishment from a host. An interspecific interaction that benefits both species. Symbiotic relationship that benefits one of the species but neither harms nor helps the other. A fern growing in the shade of another plant is an example. When individuals of 2 or more species live in direct contact with one another. Parasitism Mutualism Commenalism

Dominant Species Dominant Species Population in a community that has the highest biomass Biomass is the sum weight of all the members of a population.

Keystone Species Keystone species exert strong control on a community by their ecological roles, or niches A keystone species has a much larger impact on its community than its biomass would suggest. Field studies of sea stars illustrate their role as a keystone species in intertidal communities Keystone Keystone absent

The urchin population annihilates coral reefs
Pisaster ochraceus may prey on sea urchins & mussels with no other natural predators. If the sea star is removed from the ecosystem, the mussel population explodes, driving out most other species The urchin population annihilates coral reefs Figure 37.11B A Pisaster sea star, a keystone species, eating a mussel.

Number of species present
Figure 54.17 EXPERIMENT RESULTS Figure Inquiry: Is Pisaster ochraceus a keystone predator? 20 15 With Pisaster (control) Number of species present 10 Without Pisaster (experimental) 5 1963 ’64 ’65 ’66 ’67 ’68 ’69 ’70 ’71 ’72 ’73 Year

Number of species present
Figure 54.17b RESULTS 20 15 With Pisaster (control) Number of species present 10 Without Pisaster (experimental) 5 Figure Inquiry: Is Pisaster ochraceus a keystone predator? 1963 ’64 ’65 ’66 ’67 ’68 ’69 ’70 ’71 ’72 ’73 Year

Keystone species: Otters

Keystone Species: The engineering Beaver
The beaver is an ecosystem engineer transforms its territory from a stream to a pond or swamp. Beavers affect the environment by cutting down older trees to use for their dams. allows younger trees to take their place. Beaver dams alter the riparian area (where water and land interact) Dams change the edges of streams and rivers into wetlands, meadows, or riverine forests. Beneficial to groups of species such as amphibians, salmon, and song birds

Community Disturbance
Disturbances Events that damage biological communities Storms, fire, floods, droughts, overgrazing, or human activity The types, frequency, and severity of disturbances vary from community to community Student Misconceptions and Concerns 1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems. 2. The idea that ecosystems are relatively stable is common. Natural disturbances of any sort (fires, earthquakes, floods, or strong storms) are typically viewed as tragic and damaging to ecosystems. Before beginning the topic of ecological disturbances, consider asking your students to briefly respond to news that a state or federal park has (a) been burned, (b) been struck by high winds and/or lightning, or (c) been temporarily flooded. In addition, consider asking what, if anything, should be done to prevent or repair this damage? Teaching Tips 1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights. 2. Before and after images of the impact and recovery of an ecosystem from a natural disaster can be more powerful than any verbal explanation of the process. 3. Depending upon your location and its circumstances, consider a short field trip on or near your campus to show disturbed regions and signs of recovery.

Communities change drastically following a severe disturbance Ecological succession Colonization by a variety of species A success of change gradually replaces other species Student Misconceptions and Concerns 1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems. 2. The idea that ecosystems are relatively stable is common. Natural disturbances of any sort (fires, earthquakes, floods, or strong storms) are typically viewed as tragic and damaging to ecosystems. Before beginning the topic of ecological disturbances, consider asking your students to briefly respond to news that a state or federal park has (a) been burned, (b) been struck by high winds and/or lightning, or (c) been temporarily flooded. In addition, consider asking what, if anything, should be done to prevent or repair this damage? Teaching Tips 1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights. 2. Before and after images of the impact and recovery of an ecosystem from a natural disaster can be more powerful than any verbal explanation of the process. 3. Depending upon your location and its circumstances, consider a short field trip on or near your campus to show disturbed regions and signs of recovery.

Describe what populations might be part of this community?

What would likely happen if this forest burnt down?

Primary succession Begins in a virtually lifeless area with no soil Secondary succession When a disturbance destroyed an existing community but left the soil intact Student Misconceptions and Concerns 1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems. 2. The idea that ecosystems are relatively stable is common. Natural disturbances of any sort (fires, earthquakes, floods, or strong storms) are typically viewed as tragic and damaging to ecosystems. Before beginning the topic of ecological disturbances, consider asking your students to briefly respond to news that a state or federal park has (a) been burned, (b) been struck by high winds and/or lightning, or (c) been temporarily flooded. In addition, consider asking what, if anything, should be done to prevent or repair this damage? Teaching Tips 1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights. 2. Before and after images of the impact and recovery of an ecosystem from a natural disaster can be more powerful than any verbal explanation of the process. 3. Depending upon your location and its circumstances, consider a short field trip on or near your campus to show disturbed regions and signs of recovery.

Primary or secondary succession?
Figure Stages in secondary succession of abandoned farm field. Annual plants Perennial plants and grasses Shrubs Softwood trees such as pines Hardwood trees Time

After what type of natural disasters would one expect to see primary succession?

Primary Succession Primary succession could occur on the barren slopes of a recently erupted volcano.

A large-scale fire struck Yellowstone National Park in 1988.
It quickly responded. Would this be primary or secondary succession? (a) Soon after fire (b) One year after fire

ECOSYTEMS 55

What is an Ecosystem Ecosystem Components of ecosystems
All the organisms in a community as well as the abiotic environment Components of ecosystems Energy flow Passage of energy through the ecosystem Chemical cycling Transfer of materials within the ecosystem Why is this important to us? What are the four major macromolecules, what do they look like? Where do we get the material to make these molecules?

A terrarium has the components of an ecosystem
Chemical cycling Energy flow Chemical energy Light energy Heat energy Figure A terrarium ecosystem. Chemical elements Bacteria and fungi

How much Energy is Available
Primary production The amount of solar energy converted to chemical energy Carried out by producers (autotrophs) Produces biomass Amount of living organic material in an ecosystem

How much Energy is Available
The total primary production in an ecosystem is known as that system gross primary production (GPP). The amount of energy available to consumers is the net primary production (NPP). What is the difference? NPP = GPP-R R is the energy used in respiration by the producers.

Primary production of different ecosystems
Open ocean Estuary Algal beds and coral reefs Desert and semidesert scrub Tundra Temperate grassland Cultivated land Figure Net primary production of various ecosystems. Boreal forest (taiga) Savanna Temperate deciduous forest Tropical rain forest 500 1,000 1,500 2,000 2,500 Average net primary productivity (g/m2/yr)

Feeding Relationships
Trophic Levels Each step in a food chain or food web is called a trophic level. Producers make up the first trophic level. Consumers make up the second, third, or higher trophic levels. Each consumer depends on the trophic level below it for energy.

So energy is created by producers and then consumed by consumers
So energy is created by producers and then consumed by consumers. Is there a limit to the trophic levels this energy can travel?

At each stage of consumption, or trophic level, some energy is lost as heat to the environment. This is why most producers can only support 4-5 consumer levels.

Review Explain the difference between populations, communities, and ecosystems.

Ecological Pyramids Ecological Pyramids
An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.

Ecological Pyramids Energy Pyramid:
0.1% Third-level consumers 1% Second-level consumers Energy Pyramid: Shows the relative amount of energy available at each trophic level. 10% First-level consumers 100% Producers Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue.

What do you notice about the amount of stored energy as it passes from one trophic level to the next? What does this mean about the amount of living tissue (biomass) able to be supported at each level? Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue.

Tertiary 10 kcal consumers Secondary 100 kcal consumers Primary
Figure An idealized pyramid of production. Producers 10,000 kcal 1,000,000 kcal of sunlight

Ecological Pyramids The more levels that exist between a producer and a top-level consumer in an ecosystem, the less energy that remains from the original amount. Only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level.

Chemical Cycles Ecosystems are supplied with a continual influx of energy Sun Earth’s interior Life also depends on the recycling of chemicals Organisms acquire chemicals as nutrients and lose chemicals as waste products

Chemical Cycles Biogeochemical cycles
Nutrient cycles that contain both biotic and abiotic components. Cycle chemicals between organisms and the Earth Can be local or global Decomposers play a central role in biogeochemical cycles

Consumers Producers Decomposers Nutrients available to producers
3 2 Producers Decomposers 1 Nutrients available to producers 4 Figure A general model of biogeochemical cycling of nutrients. Abiotic reservoir Geologic processes

The Carbon Cycle Carbon is the major ingredient of all organic molecules The return of CO2 to the atmosphere by respiration closely balances its removal by photosynthesis The carbon cycle is affected by burning wood and fossil fuels (these increase CO2 in the atmosphere)

The Carbon Cycle CO2 in atmosphere 5 Burning 3 Photosynthesis
Cellular respiration 1 Plants, algae, cyanobacteria Higher-level consumers 2 Wood and fossil fuels Primary consumers Decomposition Wastes; death Plant litter; death Decomposers (soil microbes) 4 Detritus

The Nitrogen Cycle Moves nitrogen from the atmosphere through the living world. Nitrogen is a common limiting factor of plant growth.

The Nitrogen Cycle Nitrogen is an essential component of proteins and nucleic acids Nitrogen has two abiotic reservoirs Air Soil Nitrogen fixation converts N2 to nitrogen used by plants Carried out by some bacteria and cyanobacteria

Nitrogen Cycle The Nitrogen Cycle
Certain types of bacteria that live in the soil and on the roots of plants can convert nitrogen gas (N2) into ammonia in a process known as nitrogen fixation.

Nitrogen Cycle Other bacteria in the soil convert ammonia into nitrates and nitrites in a process known as nitrification. Once these products are available, producers can use them to make proteins. Consumers then eat the producers and reuse the nitrogen to make their own proteins.

Nitrogen (N2) in atmosphere
8 Plant Animal 6 Organic compounds Organic compounds Assimilation by plants Nitrogen fixation 1 5 Death; wastes Denitrifiers 3 Nitrogen-fixing bacteria in root nodules Nitrates in soil (NO3–) Detritus Figure The nitrogen cycle. Free-living nitrogen-fixing bacteria and cyanobacteria Decomposers Nitrifying bacteria 4 7 Decomposition Nitrogen fixation Ammonium (NH4+) in soil 2

The Water Cycle Water moves between the ocean, atmosphere, and land.
This diagram shows the main processes involved in the water cycle. Scientists estimate that it can take a single water molecule as long as 4000 years to complete one cycle.

The Water Cycle Water molecules enter the atmosphere as water vapor, a gas, when they evaporate from the ocean or other bodies of water.

The Water Cycle Water can also enter the atmosphere by evaporating from the leaves of plants in the process of transpiration.

The Water Cycle Water vapor condenses into tiny droplets that form clouds. The water returns to Earth’s surface in the form of precipitation. Water enters streams or seeps into soil where it enters plants through their roots. Water can also infiltrate the ground and travel as groundwater.

You should now be able to
Describe the characteristics of a community Explain how interspecific interactions affect the dynamics of populations Describe the trophic structure of a community Explain how species diversity is measured Describe the role of environmental disturbance on ecological succession Explain energy and nutrient cycling in ecosystems Copyright © 2009 Pearson Education, Inc.

Review Why is it important to study communities? What is a community?
Give both an aquatic and land organism examples of predation. Give both an aquatic and land organism examples of mutualism. Give both an aquatic and land organism examples of competition. Give an example of commensalism. Give an example of parastism.

Review II Name two adaptations that may enable predators to capture prey. Name two adaptations that may enable prey to evade predators. Write a brief (fiction or nonfictional) scenario about two organisms coevolving in a predator-prey relationship. Write a brief (fiction or nonfictional) scenario about two organisms coevolving in a mutualism relationship.

Review Imagine the fields behind the school as an ecosystem:
Name a producer, primary consumer, and secondary consumer. How much of the producers potential energy will be consumed to the secondary consumer? From where does each trophic level obtain its carbon & nitrogen? Think back to musical chairs… when would one expect interspecific competition occur?

Review What are detritivores and what do they do for an ecosytem?
Explain what is meant by species richness in an ecosytem. What are keystone species and what would happen if they were removed from an ecosystem? Explain and provide examples of primary & secondary succession. Explain what invasive species are and the impact they play on an ecosystem.

Explain what this equation means: NPP = GPP – Ra
Net Primary Production = Gross – energy used in respiration

What could impact primary production in aquatic ecosystems?
Amount of light and the depth it can reach. Light decreases with depth. What is a limiting factor? Limits growth of populations Most common limiting factors in marine environments are nitrogen and phosphorous. A lake that is nutrient-rich and supports a vast array of algae is said to be eutrophic.

Chapter 56 (only section 1)
Conservation Biology Conservation Biology and Global Change Chapter 56 (only section 1)

Overview: Scientists have named and described 1.8 million species
Biologists estimate 10–200 million species exist on Earth Tropical forests contain some of the greatest concentrations of species and are being destroyed at an alarming rate Humans are rapidly pushing many species toward extinction

What will be the fate of this newly described bird species?
Figure 56.1 What will be the fate of this newly described bird species?

Figure 56.2 Figure 56.2 Tropical deforestation in West Kalimantan, an Indonesian province.

Conservation biology, which seeks to preserve life, integrates several fields
Ecology Physiology Molecular biology Genetics Evolutionary biology

Restorative Biology Bioremediation: Bioaugmentation:
Using organisms, like prokaryotes, plants and fungi to detoxify polluted ecosystems. Bioaugmentation: Is the intorduction of desirable species such as nitrogen fixers to add essential nutrients.

Concept 56.1: Human activities threaten Earth’s biodiversity
Rates of species extinction are difficult to determine under natural conditions The high rate of species extinction is largely a result of ecosystem degradation by humans Humans are threatening Earth’s biodiversity

Three Levels of Biodiversity
Biodiversity has three main components Genetic diversity Species diversity Ecosystem diversity

Genetic diversity in a vole population Species diversity in a coastal
Figure 56.3 Genetic diversity in a vole population Species diversity in a coastal redwood ecosystem Figure 56.3 Three levels of biodiversity. Community and ecosystem diversity across the landscape of an entire region

Genetic Diversity Genetic diversity comprises genetic variation within a population and between populations

Species Diversity Species diversity is the variety of species in an ecosystem or throughout the biosphere According to the U.S. Endangered Species Act An endangered species is “in danger of becoming extinct throughout all or a significant portion of its range” A threatened species is likely to become endangered in the foreseeable future

Conservation biologists are concerned about species loss because of alarming statistics regarding extinction and biodiversity Globally, 12% of birds, 20% of mammals, and 32% of amphibians are threatened with extinction Extinction may be local or global

Philippine eagle Yangtze River dolphin Javan rhinoceros Figure 56.4
Figure 56.4 A hundred heartbeats from extinction. Javan rhinoceros

Ecosystem Diversity Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere More than 50% of wetlands in the contiguous United States have been drained and converted to other ecosystems

The local extinction of one species can have a negative impact on other species in an ecosystem
For example, flying foxes (bats) are important pollinators and seed dispersers in the Pacific Islands

Figure 56.5 Figure 56.5 The endangered Marianas “flying fox” bat (Pteropus mariannus), an important pollinator.

Biodiversity and Human Welfare
Human biophilia allows us to recognize the value of biodiversity for its own sake Species diversity brings humans practical benefits

Benefits of Species and Genetic Diversity
Species related to agricultural crops can have important genetic qualities For example, plant breeders bred virus- resistant commercial rice by crossing it with a wild population In the United States, 25% of prescriptions contain substances originally derived from plants For example, the rosy periwinkle contains alkaloids that inhibit cancer growth

Figure 56.6 Figure 56.6 The rosy periwinkle (Catharanthus roseus), a plant that saves lives.

The loss of species also means loss of genes and genetic diversity
The enormous genetic diversity of organisms has potential for great human benefit

Ecosystem Services Ecosystem services encompass all the processes through which natural ecosystems and their species help sustain human life Some examples of ecosystem services Purification of air and water Detoxification and decomposition of wastes Cycling of nutrients Moderation of weather extremes

Threats to Biodiversity
Most species loss can be traced to four major threats Habitat destruction Introduced species Overharvesting Global change

Habitat Loss Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere In almost all cases, habitat fragmentation and destruction lead to loss of biodiversity For example In Wisconsin, prairie occupies <0.1% of its original area About 93% of coral reefs have been damaged by human activities

Figure 56.7 Figure 56.7 Habitat fragmentation in the foothills of Los Angeles.

Introduced Species Introduced species are those that humans move from native locations to new geographic regions Without their native predators, parasites, and pathogens, introduced species may spread rapidly Introduced species that gain a foothold in a new habitat usually disrupt their adopted community

Sometimes humans introduce species by accident
For example, the brown tree snake arrived in Guam as a cargo ship “stowaway” and led to extinction of some local species

Humans have deliberately introduced some species with good intentions but disastrous effects
For example, kudzu was intentionally introduced to the southern United States Kudzua climbing, coiling, and trailing vine native to southern Japan and south east China. As an invasive species, it climbs over trees or shrubs and grows so rapidly, it kills them by heavy shading.

Figure 56.8b Figure 56.8 Two introduced species. (b) Kudzu

Overharvesting Overharvesting is human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound Large organisms with low reproductive rates are especially vulnerable to overharvesting For example, elephant populations declined because of harvesting for ivory

DNA analysis can help conservation biologists identify the source of illegally obtained animal products For example, DNA from illegally harvested ivory can be used to trace the original population of elephants to within a few hundred kilometers

Figure 56.9 Figure 56.9 Impact: Forensic Ecology and Elephant Poaching

Overfishing has decimated wild fish populations
For example, the North Atlantic bluefin tuna has decreased by 80% in ten years

Figure 56.10 Figure Overharvesting.

Global Change Global change includes alterations in climate, atmospheric chemistry, and broad ecological systems Acid precipitation contains sulfuric acid and nitric acid from the burning of wood and fossil fuels

Acid precipitation kills fish and other lake- dwelling organisms
Air pollution from one region can result in acid precipitation downwind For example, industrial pollution in the midwestern United States caused acid rain in eastern Canada in the 1960s Acid precipitation kills fish and other lake- dwelling organisms Environmental regulations have helped to decrease acid precipitation For example, sulfur dioxide emissions in the United States decreased 31% between and 2002

Figure 56.11 4.7 4.6 4.5 4.4 pH 4.3 4.2 Figure Changes in the pH of precipitation at Hubbard Brook, New Hampshire. 4.1 4.0 1960 ‘65 ‘70 ‘75 ‘80 ‘85 ‘90 ‘95 2000 ‘05 ‘10 Year

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