45 lecture ppt

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Biology

Sylvia S. Mader Michael Windelspecht

Chapter 45 Community and

Ecosystem

Ecology

Lecture Outline

See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into

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Outline

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45.1 Ecology of Communities

• Community Structure



A

community

is an assemblage of

populations interacting with one another

within the same environment.

• The species composition (also called species

richness) of a community is a listing of various

species in the community.

• Species diversity includes both species richness

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Community Structure

a. b.

(forest): © Charlie Ott/Photo Researchers,Inc.; (squirrel): © Stephen Dalton/Photo Researchers,Inc.; (wolf): © Renee Lynn/Photo Researchers, Inc.; (rain forest): © Michael Graybill and Jan Hodder/ Biological Photo Service; (kinkajou): © Alan & Sandy Carey/Photo Researchers, Inc.;

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Ecology of Communities

• Habitat and Ecological Niche



Habitat

• The area where an organism lives and reproduces



Ecological niche

• The role a species plays in its community

– Includes its habitat and its interactions with other organisms • Fundamental niche - All conditions under which the

organism can survive

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Ecology of Communities

• Competition Between Populations



Competition occurs when members of

different species try to utilize a limited

resource

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Competition Between

Two Laboratory Populations of

Paramecium

P o p u latio n Densit y P o p u latio n Densit y n Densit y

P. aurelia grown separately

P. caudatum grown separately

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Ecology of Communities

• Competition Between Populations

 Competitive Exclusion Principle

• No two species can indefinitely occupy the same niche at the same time

• Resource partitioning decreases competition between species • Resource partitioning leads to niche specialization and less niche

overlap between species

 Character Displacement

• Characteristics tend to become more divergent when populations belong to the same community than when they are isolated

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Character Displacement in Finches

on the Galápagos Islands

30 10 50 P e rc e nt of S a m pl e small large 30 10 50 P e rc e nt of S a m pl e small large 30 50 e nt of S a m pl e

Species coexist on Abingdon, Bindloe, James, and Jervis Islands

medium Beak Depth

G. fortis exists alone on Daphne Island

G. fuliginosa exists alone on Crossman Island

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Niche Specialization Among

Five Species of Coexisting Warblers

Cape May warbler

Black-throated green warbler

Bay-breasted warbler

Blackburnian warbler

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Competition Between

Two Species of Barnacles

Chthamalus

Balanus high tide

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Ecology of Communities

• Predator-Prey Interactions



Predation

• One living organism, the predator, feeds on another, the prey

– Predator is larger

– Predator has lower reproductive rate – Prey usually entirely consumed

• Presence of predators can decrease prey densities, and vice-versa

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Island Biogeography Pertains to

Biodiversity

• MacArthur and Wilson



Developed a general model of island

biogeography



Explains and predicts how the community

diversity of an island is affected by

• Distance from the mainland, and • Size of the island

• The model of island biogeography

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Predator-prey Interaction

Between a Lynx and a Snowshoe Hare

a. hare lynx 140 120 100 80 60 40 20 b.

1845 1855 1865 1875 1885 1895 1905 1915 1925 1935

N umb er ( tho usa nd s)

(a): © Creatas/Punch-Stock RF; (b): Data from D.A. MacLulich, Fluctuations in the Numbers of the Varying Hare

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Ecology of Communities

• Prey defenses



Mechanisms that thwart the possibility of

being eaten by a predator

• Heightened senses • Speed

• Protective armor

• Protective spines or thorns

• Tails or appendages that break off • Poisonous chemicals

• Camouflage

• Warning coloration

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Antipredator Defenses

eye

false head a. Camouflage b. Warning colorization c. Fright

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Ecology of Communities

• Mimicry



One species resembles another species that

possesses an overt antipredator defense



Batesian Mimicry - Mimic lacks defense of the

organism it resembles

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Mimicry Among Insects

a. Flower fly b. Longhorn beetle

c. Bumblebee d. Yellow jacket

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Ecology of Communities

• Symbiotic Relationships



Symbiosis

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Ecology of Communities

• Symbiotic Relationships (continued)



Parasitism

• Parasite derives nourishment from a host, and may

use host as habitat and mode of transmission • Small parasites tend to be endoparasites

– Ex: heartworms

• Larger parasites tend to be ectoparasites

– Ex: leeches

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Heartworm

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Ecology of Communities

• Symbiotic Relationships (continued)



Commensalism

• A symbiotic relationship in which one species benefits and the other is neither benefited nor harmed

– Clownfish living within tentacles of sea anemones

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Clownfish Among

Sea Anemone’s Tentacles

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Ecology of Communities

• Symbiotic Relationships (continued)



Mutualism

• A symbiotic relationship in which both members of the association benefit

• Need not be equally beneficial to both species

– Cleaning symbiosis

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Cleaning Symbiosis

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45.2 Community Development

• Ecological Succession



A change involving a series of species

replacements following a disturbance

• Primary succession occurs in areas where there is no soil formation

• Secondary succession begins in areas where soil is present

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Secondary Succession

a. First year b. Second year

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Secondary Succession in a Forest

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Community Development

• Models About Succession



Facilitation Model

• Each stage facilitates invasion and replacement by organisms of the next stage

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Community Development

• Models About Succession



Inhibition Model

• Colonists remain and inhibit growth of other plants until the colonists are damaged or die



Tolerance Model

• Different types of plants can colonize an area at the same time

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45.3 Dynamics of an Ecosystem

• In an

ecosystem

,



Populations interact among themselves



Populations interact with the physical

environment



The abiotic components of an ecosystem are

the nonliving components:

• Atmosphere • Water

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Dynamics of an Ecosystem



The

biotic components

of an

ecosystem are living things that can be

categorized according to their food

source:

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Dynamics of an Ecosystem

• Autotrophs



Require only energy and inorganic nutrients

• Generate the food necessary for the ecosystem



Require only inorganic nutrients and an outside

energy source to produce organic nutrients



Photoautotrophs

• Land plants and algae



Chemoautotrophs

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Biotic Components: Producers

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Dynamics of an Ecosystem

• Heterotrophs

 Need a preformed source of organic nutrients as they acquire food

 Consumers – consume food generated by a producer

• Herbivores - Feed on plants

• Carnivores - Feed on other animals

• Omnivores - Feed on plants and animals

• Detritivores – Feed on decomposing organic matter

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Biotic Components: Herbivores

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Biotic Components: Carnivores

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c. Carnivores

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Biotic Components: Decomposers

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Dynamics of an Ecosystem

• Energy Flow

 Every ecosystem is characterized by two fundamental phenomena:

• Energy flow

– Begins when producers absorb solar energy – Make organic nutrients via photosynthesis – Organic nutrients are used by themselves – Organic nutrients are used by others

– Energy eventually dissipates into the environment as heat

• Chemical cycling

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Nature of an Ecosystem

Inorganic nutrient pool solar

energy

producers

heat

consumers

heat

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Dynamics of an Ecosystem

• Energy Flow

 Energy flows through an ecosystem via

photosynthesis

 Only a portion (10%) of the organic nutrients made

by producers is passed on to consumers

• Organisms use organic molecules to fuel their own metabolism, growth, and reproduction

• Additional energy is lost through excretion, defecation, and organisms that die without being consumed

• A food web

 Represents interconnecting paths of energy flow

 Describes trophic relationships

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Energy Balances

growth and reproduction

Heat to environment

Energy to carnivores

Energy to detritus

feeders

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Dynamics of an Ecosystem

• Energy Flow



A food web

• Represents interconnecting paths of energy flow within ecosystems

• Describes trophic (feeding) relationships

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Dynamics of an Ecosystem

• An Example of Energy Flow



A grazing food web begins with a producer, in

this case an oak tree.



Insects, rabbits, and deer feed on leaves.



Birds, chipmunks, and mice feed on fruits and

nuts.

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Dynamics of an Ecosystem

• An Example of Energy Flow (continued)

 A detrital food web begins with detritus

• Detritus is food for soil organisms such as earthworms.

• Earthworms are in turn fed on by carnivorous invertebrates. • Invertebrates may be eaten by shrews or salamanders.  A detrital food web member may become food for

above ground carnivores, so the detrital and grazing food webs are joined.

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Grazing and Detrital Food Web

nuts

Autotrophs Herbivores/Omnivores Carnivores

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Dynamics of an Ecosystem

• Trophic Levels



A

food chain

is a diagram showing a single

path of energy flow in an ecosystem.



Trophic level

• A level of nourishment within a food web or chain • Composed of all the organisms that feed at the

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Dynamics of an Ecosystem

• Ecological Pyramids



Only about 10% of the energy of one trophic

level is available to the next trophic level

• Explains why few top carnivores can be supported in a food web



Ecological pyramids

• Depict the flow of energy with large losses between successive trophic levels

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Ecological Pyramid

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top carnivores 1.5 g/m2

carnivores 11 g/m2

herbivores 37 g/m2

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Dynamics of an Ecosystem

• Ecological Pyramids



Pyramids of biomass

• Biomass

– Number of organisms x dry weight of the organic matter within one organism

• Biomass of the producers is expected to exceed the herbivores, which should exceed that of the

carnivores

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Inverted Pyramid of Biomass

zooplankton

phytoplankton

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Dynamics of an Ecosystem

• Chemical Cycling



The pathways by which chemicals circulate

through ecosystems

• Involve both living (biotic) and nonliving (geologic) components

• Known as biogeochemical cycles

– Water Cycle – Carbon Cycle

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Dynamics of an Ecosystem

• Chemical Cycling



May involve:

• Reservoir - Source normally unavailable to producers

– Ex: carbon present in calcium carbonate shells on ocean bottoms

• Exchange Pool - Source from which organisms generally take chemicals

– Ex: Atmosphere, soil

• Biotic Community - Chemicals remain in food chains, perhaps never entering a pool

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Model for Chemical Cycling

Reservoir • fossil fuels

• atmosphere • soil • water

Community • mineral

in rocks • sediment

in oceans Exchange Pool

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Dynamics of an Ecosystem

• The Water (hydrologic) Cycle



Transfer rate

• The amount of a substance that moves from one component of the environment to another with a specified period of time



Fresh water evaporates from bodies of water



Precipitation on land enters the ground,

surface waters, or aquifers

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The Hydrologic (Water) Cycle

net transport of water vapor by wind

Ocean Ice

Groundwaters lake

aquifer freshwater runoff

H2O in Atmosphere

evaporation from ocean

precipitation to ocean

transpiration from plants

and evaporation from soil precipitation over land

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Dynamics of an Ecosystem

• The Carbon Cycle

 Atmosphere is an exchange pool for carbon dioxide

 In water, carbon dioxide combines with water to produce bicarbonate ions

 Bicarbonate in the water is in equilibrium with carbon dioxide in the air

 The total amount of carbon dioxide in the atmosphere has been increasing every year due to human

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The Carbon Cycle

Land plants Soils Ocean combustion photosynthesis respiration decay runoff diffusion sedimentation coal oil destruction of vegetation

CO2in Atmosphere

dead organisms and animal waste natural

gas

bicarbonate (HCO3–)

1 5 4 2 6 6 6 3

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Dynamics of an Ecosystem

• The Carbon Cycle (continued)



Greenhouse effect

• Carbon dioxide, nitrous oxide, methane

• Allow sunlight to pass through atmosphere • Reflect infrared back to earth

• Trap heat in atmosphere

• Leads to global warming and climate change



If Earth’s temperature rises

• More water will evaporate • More clouds will form, and

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Dynamics of an Ecosystem

• The Phosphorous Cycle

 Phosphorous from ocean sediments moves on to land via geologic activity

 Weathering of rocks results in the deposition of phosphate ions in the soil

 Phosphate ions become available to plants

 Animals obtain phosphate by consuming producers

 Death and decay returns phosphate ions to the soil, and to producers, again.

 Some phosphate runs off into aquatic ecosystems • Excessive phosphorous levels can lead to

eutrophication

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The Phosphorus Cycle

62 3 organisms mineable rock phosphate mining detritus Ocean sedimentation runoff fertilizer plants animals decomposers geologic uplift weathering 8 2 sewage treatment plants 7 8

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Dynamics of an Ecosystem

• Nitrogen Cycle



Atmospheric nitrogen is fixed (

nitrogen

fixation

) by bacteria

• Made available to plants • Nodules on legume roots



Nitrification

- Production of nitrates, which

plants can use as a source of nitrogen



Assimilation

-plants take up ammonium and

nitrates from the soil and use them to produce

proteins and nucleic acids

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The Nitrogen Cycle

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plants

phytoplankton

decomposers

NO3

-NO3

-NH4+

NH4+

sedimentation cyanobacteria runoff decomposers denitrification denitrifying bacteria nitrification denitrification N2fixation

nitrogen-fixing bacteria in nodules

and soil plant and animal waste Biotic Community nitrifying bacteria denitrifying bacteria Biotic Community human activities

N2fixation

N2in Atmosphere

1 3 2 ₄ 5 4 3 2 2 1

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Dynamics of an Ecosystem

• Human activities and the Nitrogen Cycle



Acid Deposition

• Nitrogen oxides and sulfur dioxide are converted to acids when they combine with water vapor