50 Ecologyintro Text

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PowerPoint Lectures for

Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 50


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Overview: The Scope of Ecology

Ecology

Is the scientific study of the interactions between

organisms and the environment

These interactions

Determine both the distribution of organisms and

their abundance


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Ecology

Is an enormously complex and exciting area ofbiology

Reveals the richness of the biosphere

Figure 50.1


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Concept 50.1: Ecology is the study of

interactions between organisms and theenvironment

Ecology

Has a long history as a descriptive science

Is also a rigorous experimental science


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Ecology and Evolutionary Biology

Events that occur in ecological time

Affect life on the scale of evolutionary time


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Organisms and the Environment

The environment of any organism includes

Abiotic, or nonliving components

Biotic, or living components

All the organisms living in the environment, thebiota


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Environmental components

Affect the distribution and abundance oforganisms

Figure 50.2

Kangaroos/km2

> 20

1020

510

15

0.11

< 0.1

Limits of

distribution

Climate in northern Australia

is hot and wet, with seasonal

drought.

Red kangaroos

occur in most

semiarid and arid

regions of the

interior, where

precipitation is

relatively low and

variable from

year to year.

Southeastern Australia

has a wet, cool climate.Southern Australia has

cool, moist winters and

warm, dry summers.Tasmania


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Ecologists

Use observations and experiments to testexplanations for the distribution and

abundance of species


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Subfields of Ecology

Organismal ecology

Studies how an organisms structure, physiology,and (for animals) behavior meet the challenges

posed by the environment

Figure 50.3a

(a) Organismal ecology. How do humpback whales

select their calving areas?


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Population ecology

Concentrates mainly on factors that affect howmany individuals of a particular species live in

an area

Figure 50.3b

Population ecology.

What environmental

factors affect the

reproductive rate of

deer mice?

(b)


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Community ecology

Deals with the whole array of interacting speciesin a community

Figure 50.3c

(c) Community ecology.

What factors influence

the diversity of species

that make up a

particular forest?


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Ecosystem ecology

Emphasizes energy flow and chemical cyclingamong the various biotic and abiotic

components

Figure 50.3d

(d) Ecosystem ecology. What

factors control photosynthetic

productivity in a temperate

grassland ecosystem?


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Landscape ecology

Deals with arrays of ecosystems and how theyare arranged in a geographic region

Figure 50.3e

(e) Landscape ecology. To what extent do the trees lining

the drainage channels in this landscape serve as corridors

of dispersal for forest animals?


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The biosphere

Is the global ecosystem, the sum of all theplanets ecosystems


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Ecology and Environmental Issues

Ecology

Provides the scientific understanding underlyingenvironmental issues

Rachel Carson

Is credited

with starting

the modern

environmentalmovement

Figure 50.4


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Most ecologists follow the precautionary

principle regarding environmental issues The precautionary principle

Basically states that humans need to be

concerned with how their actions affect the

environment


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Many naturalists

Began to identify broad patterns of distribution bynaming biogeographic realms

Tropic

of Cancer

(23.5N)

Equator

Nearctic

Neotropical

Ethiopian

Oriental

Australian

Palearctic

(23.5S)

Tropic of

CapricornFigure 50.5


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Biogeography

Provides a good starting point for understandingwhat limits the geographic distribution of

species

Figure 50.6

Species absent

because

Yes

No

Dispersal

limits

distribution?Behavior

limits

distribution?

Biotic factors

(other species)

limit

distribution?

Abiotic factors

limit

distribution?

Yes

No

Yes

No

Area inaccessible

or insufficient time

Habitat selectionPredation, parasitism,

competition, diseaseWater

Oxygen

Salinity

pHSoil nutrients, etc.

Temperature

Light

Soil structure

Fire

Moisture, etc.

Chemical

factors

Physical

factors


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Dispersal and Distribution

Dispersal

Is the movement of individuals away from centersof high population density or from their area of

origin

Contributes to the global distribution of organisms


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New areas

occupied Year

1996

1989

1974

Natural Range Expansions

Natural range expansions

Show the influence of dispersal on distribution

Figure 50.7


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Species Transplants

Species transplants

Include organisms that are intentionally oraccidentally relocated from their original

distribution

Can often disrupt the communities or ecosystemsto which they have been introduced


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Behavior and Habitat Selection

Some organisms

Do not occupy all of their potential range

Species distribution

May be limited by habitat selection behavior


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Biotic Factors

Biotic factors that affect the distribution of

organisms may includeInteractions with other species

Predation

Competition


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A specific case of an herbivore limiting

distribution of a food species

Figure 50.8

W. J. Fletcher tested the effects of two algae-eating animals, sea urchins and limpets, on seaweed

abundance near Sydney, Australia. In areas adjacent to a control site, either the urchins, the limpets, or both were removed.

EXPERIMENT

RESULTS Fletcher observed a large difference in seaweed growth between areas with and without sea urchins.

100

80

60

40

20

0

Limpet

Sea

urchin Both limpets

and urchins

removed

Only

urchins

removed

Only limpets removed

August

1982

February

1983

August

1983

February

1984

Control (both

urchins andlimpets present)

Seaweedcover(%)

Removing both

limpets and

urchins or

removing only

urchins increased

seaweed cover

dramatically.

Almost no

seaweed grew

in areas where

both urchins and

limpets were

present, or whereonly limpets were

removed.

Removing both limpets and urchins resulted in the greatest increase of seaweed cover, indicating that both

species have some influence on seaweed distribution. But since removing only urchins greatly increased seaweed growth while

removing only limpets had little effect, Fletcher concluded that sea urchins have a much greater effect than limpets in limiting

seaweed distribution.

CONCLUSION

A i i


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Abiotic Factors

Abiotic factors that affect the distribution of

organisms may include

Temperature

Water

Sunlight

Wind

Rocks and soil

T


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Temperature

Environmental temperature

Is an important factor in the distribution oforganisms because of its effects on biological

processes

W


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Water

Water availability among habitats

Is another important factor in species distribution

S li h


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Sunlight

Light intensity and quality

Can affect photosynthesis in ecosystems

Light

Is also important to the development andbehavior of organisms sensitive to the

photoperiod

Wi d


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Wind

Wind

Amplifies the effects of temperature on organismsby increasing heat loss due to evaporation and

convection

Can change the morphology of plants

Figure 50.9

R k d S il


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Rocks and Soil

Many characteristics of soil limit the distribution

of plants and thus the animals that feed upon

them

Physical structure

pH

Mineral composition

Cli t


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Climate

Four major abiotic components make up

climate

Temperature, water, sunlight, and wind

Climate

Is the prevailing weather conditions in a particular

area


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Climate patterns can be described on two

scales

Macroclimate, patterns on the global, regional,

and local level

Microclimate, very fine patterns, such as thoseencountered by the community of organisms

underneath a fallen log

Gl b l Cli t P tt


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Global Climate Patterns

Earths global climate patterns

Are determined largely by the input of solarenergy and the planets movement in space


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Sunlight intensity

Plays a major part in determining the Earthsclimate patterns

Figure 50.10

Low angle of incoming sunlight

Sunlight directly overhead

Low angle of incoming sunlight

North Pole

60N

30N

Tropic of

Cancer

0 (equator)

30S

60S

Atmosphere

LALITUDINAL VARIATION IN SUNLIGHT INTENSITY

Tropic of

Capricorn

South pole


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Regional Local and Seasonal Effects on Climate


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Regional, Local, and Seasonal Effects on Climate

Various features of the landscape

Contribute to local variations in climate

Bodies of Water


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Bodies of Water

Oceans and their currents, and large lakes

Moderate the climate of nearby terrestrialenvironments

Figure 50.11

Cooler

air sinks

over water.

3

Air cools at

high elevation.

2 1 Warm air

over land rises.

4 Cool air over water

moves inland, replacing

rising warm air over land.


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Seasonality


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Seasonality

The angle of the sun

Leads to many seasonal changes in localenvironments


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Lakes

Are sensitive to seasonal temperature change

Experience seasonal turnover

Figure 50.13

In spring, as the sun melts the ice, the surface water warms to 4Cand sinks below the cooler layers immediately below, eliminating the

thermal stratification. Spring winds mix the water to great depth,bringing oxygen (O2) to the bottom waters (see graphs) and

nutrients to the surface.

2

In winter, the coldest water in the lake (0C) lies just

below the surface ice; water is progressively warmer atdeeper levels of the lake, typically 45C at the bottom.

1

In autumn, as surface water cools rapidly, it sinks below theunderlying layers, remixing the water until the surface begins

to freeze and the winter temperature profile is reestablished.

4 In summer, the lake regains a distinctive thermal profile, with

warm surface water separated from cold bottom water by a narrow

vertical zone of rapid temperature change, called a thermocline.

3

Winter Spring

High

Medium

Low

O2 concentration

O2 (mg/L)

Lakedepth(m)

0 4 8 12

8

16

24

8

16

24

Lakedepth(m) O2 (mg/L)

O2 (mg/L)

Lakedepth(m)

0 4 8 12

8

16

24

O2 (mg/L)

Lakedepth(m)

0 4 8 12

8

16

24Autumn Summer

4C4

44

44

4C4

44

20

4C4

44

44

4C

6818

2022

5Thermocline

0 4 8 12

Microclimate


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Microclimate

Microclimate

Is determined by fine-scale differences in abioticfactors

Long-Term Climate Change


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Long-Term Climate Change

One way to predict future global climate

change

Is to look back at the changes that occurred

previously

Figure 50.14

Currentrange

Predicted

range

Overlap

(a) 4.5C warming over

next century(b) 6.5C warming over

next century


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Concept 50.3: Abiotic and biotic factors

influence the structure and dynamics of aquatic

biomes

Varying combinations of both biotic and abiotic

factorsDetermine the nature of Earths many biomes

Biomes

Are the major types of ecological associations

that occupy broad geographic regions of land

or water


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The examination of biomes will begin with

Earths aquatic biomes

Figure 50.15

30N

Tropic ofCancer

Equator

30S

Continental

shelf

Lakes

Coral reefs

Rivers

Oceanic pelagic

zone

Estuaries

Intertidal zone

Abyssal zone

(below oceanic

pelagic zone)

Key

Tropic of

Capricorn


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Aquatic biomes

Account for the largest part of the biosphere interms of area

Can contain fresh or salt water

Oceans

Cover about 75% of Earths surface

Have an enormous impact on the biosphere


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Many aquatic biomes

Are stratified into zones or layers defined by lightpenetration, temperature, and depth

Marine zonation. Like lakes, the marine environment is generally

classified on the basis of light penetration (photic and aphotic zones),

distance from shore and water depth (intertidal, neritic, and oceanic

zones), and whether it is open water (pelagic zone) or bottom (benthic

and abyssal zones).

Zonation in a lake. The lake environment is generally classified on the

basis of three physical criteria: light penetration (photic and aphotic zones),

distance from shore and water depth (littoral and limnetic zones), and

whether it is open water (pelagic zone) or bottom (benthic zone).

(a)

Littoral

zone Limneticzone

Photic

zone

Benthic

zone

Aphoticzone

Pelagic

zone

Intertidal zone

Neritic zone Oceanic zone

0

200 m

Continental

shelf

Photic zone

Pelagic

zone

Aphotic

zone

Benthic

zone

2,5006,000 m

Abyssal zone

(deepest regions of ocean floor)

(b)

Figure 50.16a, b


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Lakes

Figure 50.17An oligotrophic lake in

Grand Teton, Wyoming

A eutrophic lake in Okavango

delta, Botswana

LAKES


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Wetlands

Figure 50.17

WETLANDS

Okefenokee National Wetland Reserve in Georgia


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Streams and rivers

STREAMS AND RIVERS

Figure 50.17A headwater stream in the

Great Smoky Mountains

The Mississippi River far

form its headwaters


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Intertidal zones

Figure 50.17

INTERTIDAL ZONES

Rocky intertidal zone on the Oregon coast


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Oceanic pelagic biome

Figure 50.17 Open ocean off the island of Hawaii

OCEANIC PELAGIC BIOME


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Coral reefs

Figure 50.17 A coral reef in the Red Sea

CORAL REEFS


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Marine benthic zone

Figure 50.17 A deep-sea hydrothermal vent community

MARINE BENTHIC ZONE


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Concept 50.4: Climate largely determines the

distribution and structure of terrestrial biomes

Climate

Is particularly important in determining why

particular terrestrial biomes are found incertain areas

Climate and Terrestrial Biomes


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Climate has a great impact on the distribution

of organisms, as seen on a climograph

Figure 50.18

Desert Temperate grassland Tropical forest

Temperate

broadleaf

forest

Coniferous

forest

Arctic and

alpine

tundra

Annual mean precipitation (cm)

Annualmeantemperature(C)

100 200 300 400

30

15

0

15


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The distribution of major terrestrial biomes

30N

Tropic of

Cancer

Equator

Tropic of

Capricorn

30S

Key

Tropical forest

Savanna

Desert

Chaparral

Temperate grassland

Temperate broadleaf forest

Coniferous forest

Tundra

High mountains

Polar ice

Figure 50.19


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Tropical forest

TROPICAL FOREST

A tropical rain forest in BorneoFigure 50.20


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Desert

Figure 50.20

DESERT

The Sonoran Desert in southern Arizona


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Savanna

Figure 50.20

SAVANNA

A typical savanna in Kenya


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Chaparral

CHAPARRAL

An area of chaparral in CaliforniaFigure 50.20


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Temperate grassland

Sheyenne National Grassland in North DakotaFigure 50.20

TEMPERATE GRASSLAND


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Coniferous forest

Figure 50.20

Rocky Mountain National Park in Colorado

CONIFEROUS FOREST


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Tundra

Figure 50.20

TUNDRA

Denali National Park, Alaska, in autumn

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