Read the article and write 2 pages essay including few deatils from the chapters which are attacged below.

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Chapter4.pdf

Lecture Outlines

Withgott | Laposata

Sixth Edition

ENVIRONMENT the science behind the stories

Chapter 4

Species Interactions and Community Ecology

© 2018 Pearson Education, Inc.

Lecture objectives  Compare types of species interactions.  Describe feeding relationships and energy flow

using food webs.  Discuss characteristics of a keystone species.  Characterize disturbance, succession, and

community change.  Predict the impacts of an invasive species and

suggestion responses to it.  Explain restoration ecology.  Identify and describe terrestrial biomes of the world.

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Central Case Study: Black and White and Spread All Over: Zebra Mussels Invade the Great Lakes  In 1988, it was discovered that zebra mussels had

been introduced to the Great Lakes through ballast water discharged from European ships.  Within six years, they had spread into the Mississippi

River watershed, reaching 19 U.S. states.  They currently are found in 30 states.

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 The mussels spread quickly because they were free of predators and parasites.

 The mussels impact humans by clogging water intake pipes at factories and municipal water plants, as well as damaging docks, fishing gear, and boats.  They have cost the Great Lakes economies an

estimated $5 billion over the first 10 years.

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 Zebra mussels also have ecological impacts, including the consumption and depletion of microscopic algae, protists, and cyanobacteria called plankton.  The tiny aquatic animals that eat phytoplankton,

called zooplankton, are becoming depleted due to a lack of food.

 Native mussels are becoming suffocated by the zebra mussels.

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 The zebra mussel population may have peaked, however, due to other changes in the ecology of the Great Lakes.  The quagga mussel (Dreissena bugensis) is another

invasive species that is competing with zebra mussels.  Native fish, crabs, ducks, and other predators are

beginning to use the mussels as a food source.

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Species Interactions  Species like zebra mussels interact with their

ecological community in many ways.  Organisms that seek the same resource have a

relationship called competition.  Intraspecific competition takes place between

members of the same species.  Interspecific competition takes place between

members of different species.  Competition becomes more intense when

populations are more dense.

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 If one species is a stronger competitor, it may exclude other species from the resource. This is competitive exclusion.  Zebra mussels had this effect on native mussels.

 Otherwise, if no single competitor excludes others, species live side-by-side. This is species coexistence.

 Coexisting species will alter their behaviors to minimize competition, altering their niche.  A niche is a species role in an ecosystem, including

resource use, habitat use, food consumption, and other attributes.

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 The full potential niche of a species is called its fundamental niche.

 An individual that only plays part of its role due to competition or other interactions has a realized niche.  The quagga mussel is pushing the zebra mussel into

from a fundamental to a realized niche.

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 Over many generations, natural selection may favor resource partitioning, where individuals use shared resources in different ways.  This may lead to

character displacement, where competing species diverge and develop different characteristics.

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Predators kill and consume prey  Predation is the process by which individuals of one

species (the predators) capture, kill, and consume individuals of another (the prey).

 Predation may affect population dynamics, such as when an increase in prey favors an increase in predators and vice-versa.

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 Predators that are better at capturing prey will live longer and reproduce more. Natural selection will favor adaptations that enhance hunting.

 Prey have the risk of death as a selective pressure, causing the evolution of many types of defenses.

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Parasites exploit living hosts  Parasitism is a relationship where one organism

depends on the other for nourishment.  Parasitism, unlike predation, usually does not result in

an organism’s death.  Parasites live with their hosts in many ways:  Inside the host, such as tapeworms  On the host’s exterior, such as sea lampreys  Free-living, such as cuckoos, who lay their eggs in the

nests of other species

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 Parasites that cause disease are called pathogens.  Pathogens can be protists (malaria), bacteria

(tuberculosis), or viruses (hepatitis).  Parasites and hosts adapt and counter-adapt to

each other through a process called coevolution.

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Herbivores exploit plants  In herbivory, animals feed on the tissues of plants.  Insects are the most common type of herbivore.

 Plants have also evolved defenses, such as toxic chemicals, thorns, spines, or irritating hairs.

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Mutualists help one another  Mutualism is a relationship where two or more

species benefit each other.  Many mutualistic relationships occur as part of

symbiosis – a close physical association between species.  Others, such as in

pollination, only require free-living organisms to encounter each other once.  Birds or insects transfer

pollen from flower to flower, causing fertilization.

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Review Questions 1. Two different bird species compete for the same

kinds of insects. One is more active in the morning, the other in the evening. What is this an example of? a. Intraspecific competition b. Resource partitioning c. Competitive exclusion d. Herbivory

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Review Questions 2. Microbes are found in the digestive tract of all

humans. They are given a place to live and help to digest our food. What type of relationship is this? a. Interspecific competition b. Parasitism c. Herbivory d. Mutualism

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Ecological Communities  A community is an assemblage of populations

organisms living in the same area at the same time.  Community ecologists study which species coexist,

how they interact, how communities change over time, and why these patterns occur.

 Some of the most important interactions among community members involve who eats whom.

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Energy passes among trophic levels  Species in a community are given a rank within the

feeding hierarchy, called a trophic level.  Producers use photosynthesis or chemosynthesis

to make their own sugars.  Primary consumers consume producers.

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 Secondary consumers prey on primary consumers.

 Tertiary consumers prey on secondary consumers.

 Detritivores scavenge waste and dead bodies.

 Decomposers break down nonliving matter into smaller molecules.  These play an especially

important role in cycling nutrients back into soil for plants to use.

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Energy, numbers, and biomass decrease at higher trophic levels  At each trophic level, most of the energy input is

either used for maintenance or lost as heat.  Trophic levels will only have about 10% of energy

content, organisms, and biomass compared to the one below them.

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 Biomass is the collective mass of living matter in a given place and time.  The pyramid pattern of energy and biomass illustrates

why eating at lower trophic levels decreases your ecological footprint.

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Food webs show feeding relationships and energy flow  The flow of energy and feeding relationships from

lower to higher trophic levels is depicted in a food chain.

 Food webs incorporate all of the interlinking food chains within an entire community, showing the map of energy flow.

© 2018 Pearson Education, Inc.

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Some organisms play outsized roles  A species that has an impact far greater than its

abundance is called a keystone species. Keystone species can include:  Decomposers that recycle nutrients and replenish the

soil.  “Ecosystem engineers,” such as beavers and prairie

dogs, who physically alter ecosystems.  Top predators, who control populations of lower

trophic level consumers, are often keystone species.

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 If top predators are lost, primary consumers will overconsume producers and alter the entire ecosystem. This is called a trophic cascade.  This is one example of a disturbance.

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Communities respond to disturbance in various ways  A disturbance is any event that has rapid and

drastic effects on the community and ecosystem.  Disturbances can be small and localized, such as a

tree falling and creating a gap in the forest canopy.  Disturbances can be large, like hurricanes.  Disturbances may also recur regularly, such as prairie

fires or insect outbreaks.  A community that resists change and remains stable

shows resistance to the disturbance.  A community that is changed by a disturbance but

returns to its original state has resilience. © 2018 Pearson Education, Inc.

Succession follows severe disturbance  Severe disturbances may eliminate all or most of the

species in a community, initiating a series of changes called succession.

 Succession begins with the colonization of pioneer species.  Pioneer species, such as grasses and forbs, spread

over long distances easily and are adapted for growing quickly.

 Over time, pioneers are overtaken by longer-living climax community species, such as hardwood trees.

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 Primary succession occurs when a disturbance removes all plant or soil life.  Lichens secrete acids that break down rock,

beginning the process of soil formation.

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 Secondary succession begins with a disturbance that alters the community but leaves the soil life intact.  Farming, fires, storms, and landslides are examples.

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Communities may undergo shifts  Communities do not pass through the stages of

succession evenly; ecological conditions may promote or inhibit progression.

 At times, communities may undergo a regime shift, meaning that the entire character of the community changes from the disturbance.  Occurs from climate change, loss of a keystone

species, or introduction of an invasive species.  In some cases, human disturbance is causing

no-analog communities, which are mixtures of species that have not previously occurred on the Earth.

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Invasive species pose threats to community stability  Introduced species are non-native arrivals to a

community brought by people.  Most fail to establish populations, but the ones that

thrive are called invasive species.  Introduced species become invasive when limiting

factors that normally regulate their population growth are absent.  Lack of competition, predators, or parasites.

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 Zebra mussels became invasive and had both positive and negative impacts on communities.

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 Both zebra and quagga mussels have spread throughout the waterways of North America.

© 2018 Pearson Education, Inc.

We can respond to invasive species with control, eradication, or prevention  The problems caused by zebra and quagga mussels

led to the passage of the National Invasive Species Act of 1996.  Ships must dump their freshwater ballast at sea and

replace it with saltwater before entering the Great Lakes.

 Funding has been provided for control measures:  Applying toxic chemicals, heat, sound, electricity, UV

light, and carbon dioxide to stress the mussels.  Control and eradication has been very expensive, so

now attention is given to preventing future invasions. © 2018 Pearson Education, Inc.

Altered communities can be restored  Scientists who study restoration ecology devise

ways to restore altered areas to their condition before industrialized civilization.

 Ecological restoration may have two aims:  Restore the functionality of an ecosystem.  Return a community to its “pre-settlement” condition.

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 Nearly all the U.S. tallgrass prairie has been removed for farmland. A 1000-acre area near Chicago has been restored with native vegetation.

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 In Florida, dams, canals, and levees are being undone to restore the natural water flow to the Everglades.

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 Invasive species, such as garlic mustard and Burmese pythons, have also been removed from these areas.

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Review Questions 3. Which is an example of a secondary consumer in

this food web? a. White-tailed deer b. Deer mouse c. Eastern cottontail d. Rat snake

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Review Questions 4. A forest fire destroys most of the animal and plant

life in a community. The soil and soil life are intact. Within several decades, most of the original community has been restored. What is this an example of? a. A disturbance. b. Primary succession c. Secondary succession d. A and B e. A and C

© 2018 Pearson Education, Inc.

Earth’s Biomes  Despite communities being in very different locations

in the Earth, they often have similar structure and function.

 A regional complex of similar communities is called a biome.  Biomes are classified primarily by dominant plant type

and vegetation structure, which in turn is the result of climate.

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Climate helps determine biomes  Temperature and precipitation exert the greatest

influence over all other climatic factors.

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 Temperature and precipitation are highly correlated with latitude, creating global patterns of biomes.

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 Climate also varies with elevation. At higher altitudes:  Temperature, atmospheric pressure, and oxygen

decline.  Ultraviolet radiation increases.

 Mountains also affect climate through the rainshadow effect.  When moist air rises a steep slope, it cools and

condenses, releasing precipitation.  The air that reaches the other side of the mountain is

now very dry, creating an arid region.

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 Climate diagrams, also called climatographs, depict seasonal changes in temperature and precipitation and help to tell the story of a biome.

 Temperate deciduous forests, for example, are found at mid-latitudes and have relatively even precipitation throughout the year.  Winters are frozen, causing the trees to drop their

leaves.

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 Temperature differences between winter and summer are more extreme and rainfall diminishes in temperate grasslands.  These biomes are also known as prairie or steppe.

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 Temperate rainforests are rich in rainfall, but still found in mid-latitudes.  Mostly contain coniferous trees.  Soils are fertile, but susceptible to erosion if the

forests are cleared.

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 Tropical rainforests have dark, damp interiors, lush vegetation, and highly diverse communities.  High numbers of trees species intermixed at low

densities.  Acidic soils that are low in organic matter.

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 Tropical dry forests have wet and dry seasons that each occupy about half of the year.  Temperature is consistently warm.  Leaves are shed during the dry season.

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 Savannas are tropical grassland interspersed with acacias or other trees.  Found in dry tropical areas, including parts of Africa,

Australia, and India.  Distinct wet and dry seasons.

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 Deserts are the driest biome, receiving less than 25 cm of rain per year.  Soils have high mineral and low organic matter

content.  Animals and plants must adapt to minimize water

loss.

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 Tundras are also very dry, but are consistently cold all year.  Underground soil is permanently frozen, called

permafrost.  Tundras are unoccupied by humans, but are the most

directly impacted by air pollution and climate change.

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 Boreal forests, also called taiga, are also cold, but receive more precipitation than tundras.  They are dominated by few species of evergreen

trees.  Soils are acidic and nutrient-poor.

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 Chaparral is only found in a few small patches throughout the world.  Covered by a dense thicket of evergreen shrubs.  Mild, wet winters and warm, dry summers.  Fires are frequent.  Climate is induced by nearby oceans.

© 2018 Pearson Education, Inc.

Review Questions 5. Which is a true statement regarding this

climatograph? a. There are seasonal shifts in temperature. b. There are seasonal shifts in precipitation. c. There are seasonal shifts in both temperature and

precipitation. d. None of the above.

© 2018 Pearson Education, Inc.

Review Questions 6. What type of biome is depicted by this

climatograph? a. Tropical rainforest b. Tropical dry forest c. Temperate grassland d. Desert

© 2018 Pearson Education, Inc.

  • Slide Number 1
  • Lecture objectives
  • Central Case Study: Black and White and Spread All Over: Zebra Mussels Invade the Great Lakes
  • Slide Number 4
  • Slide Number 5
  • Slide Number 6
  • Species Interactions
  • Slide Number 8
  • Slide Number 9
  • Slide Number 10
  • Predators kill and consume prey
  • Slide Number 12
  • Parasites exploit living hosts
  • Slide Number 14
  • Herbivores exploit plants
  • Mutualists help one another
  • Review Questions
  • Review Questions
  • Ecological Communities
  • Energy passes among trophic levels
  • Slide Number 21
  • Energy, numbers, and biomass decrease at higher trophic levels
  • Slide Number 23
  • Food webs show feeding relationships and energy flow
  • Slide Number 25
  • Some organisms play outsized roles
  • Slide Number 27
  • Communities respond to disturbance in various ways
  • Succession follows severe disturbance
  • Slide Number 30
  • Slide Number 31
  • Communities may undergo shifts
  • Invasive species pose threats to community stability
  • Slide Number 34
  • Slide Number 35
  • We can respond to invasive species with control, eradication, or prevention
  • Altered communities can be restored
  • Slide Number 38
  • Slide Number 39
  • Slide Number 40
  • Review Questions
  • Review Questions
  • Earth’s Biomes
  • Climate helps determine biomes
  • Slide Number 45
  • Slide Number 46
  • Slide Number 47
  • Slide Number 48
  • Slide Number 49
  • Slide Number 50
  • Slide Number 51
  • Slide Number 52
  • Slide Number 53
  • Slide Number 54
  • Slide Number 55
  • Slide Number 56
  • Review Questions
  • Review Questions