Ecology and the Biosphere

Ecology and the Biosphere

https://www.youtube.com/watch?v=Sre8L8Yg-Qw

https://www.youtube.com/watch?v=Sre8L8Yg-Qw

Biology and Society: Penguins and Polar Bears in Peril

• The scientific debate is over.

• The great majority of scientists now agree that the global climate is changing.

• Average global temperatures have risen 0.8C (about 1.4F) over the past century, mostly over the last 30 years.

• Precipitation patterns have also changed, bringing

– longer and more intense drought to some regions and

– flooding to other areas.© 2013 Pearson Education, Inc.

Figure 18.0

• Overwhelming evidence indicates that human enterprises are responsible for the changes that are occurring.

• Our response to this crisis will determine whether circumstances improve or worsen.

Biology and Society: Penguins and Polar Bears in Peril

© 2013 Pearson Education, Inc.

AN OVERVIEW OF ECOLOGY

• Ecology is the scientific study of the interactions between organisms and their environments.

• Humans have always had an interest in other organisms and their environments.

• Extraordinary insight can be gained from a discovery-based approach of

–watching nature and

– recording its structure and processes.


Figure 18.1

Ecology and Environmentalism

• Technological innovations have enabled people to colonize almost every environment on Earth.

• Earth’s resources

– affect our survival and

– have been greatly affected by our activities.

• Environmental problems

– can be understood by the science of ecology and

– require decisions based on values and ethics.

• On a personal level, each of us makes daily choices that affect our ecological impact. © 2013 Pearson Education, Inc.

Figure 18.2

A Hierarchy of Interactions

• Many different factors can potentially affect an organism’s interaction with the environment.

– Biotic factors are

– all of the organisms in the area and

– the living component of the environment.

– Abiotic factors

– are the environment’s nonliving component and

– include chemical and physical factors, such as temperature, light, water, minerals, and air.


• An organism’s habitat

– is the specific environment it lives in and

– includes the biotic and abiotic factors of its surroundings.



• Ecology can be divided into four increasingly comprehensive levels:

1. organismal ecology,

2. population ecology,

3. community ecology, and

4. ecosystem ecology.



Figure 18.3

(a) Organismal ecology

(b) Population ecology (c) Community ecology

(d) Ecosystem ecology

• An organism is an individual living thing.

• Organismal ecology is concerned with evolutionary adaptations that enable individual organisms to meet the challenges posed by their abiotic environments.



• Population ecology

– addresses populations, groups of individuals of the same species living in a particular geographic area and

– concentrates mainly on factors that affect

– population density and

– growth.



• Community ecology

– is concerned with communities, all the organisms that inhabit a particular area and

– focuses on how interactions between species affect a community’s

– structure and

– organization.



• Ecosystem ecology

– is concerned with ecosystems, all the abiotic factors in addition to the community of species in a certain area and

– focuses on energy flow and the cycling of chemicals among the various abiotic and biotic factors.



• The biosphere is

– the global ecosystem,

– the sum of all the planet’s ecosystems, or

– all of life and where it lives.



LIVING IN EARTH’S DIVERSE ENVIRONMENTS

• The distribution of life varies on a

– global scale and

– local scale.


Figure 18.4

Abiotic Factors of the Biosphere

• Patterns in the distribution of life mainly reflect differences in the abiotic factors of the environment.

• In other words, the rocks and weather


Energy Source

• All organisms require a usable source of energy to live.

• Solar energy from sunlight

– is captured by chlorophyll during the process of photosynthesis and

– powers most ecosystems.


Figure 18.5

• Hydrothermal vents

– occur a mile or more below the ocean’s surface and

– are ecosystems powered by chemoautotrophic bacteria that derive energy from the oxidation of inorganic chemicals such as hydrogen sulfide.

• Bacteria with similar metabolic talents support communities of cave-dwelling organisms.

Energy Source


Figure 18.6

• Temperature affects metabolism.

– Few organisms can maintain a sufficiently active metabolism at temperatures close to 0ºC.

– Temperatures above 45ºC destroy the enzymes of most organisms.

• Most organisms function best within a specific range of environmental temperatures.

Temperature


Figure 18.7

Water

• Water is essential to all life.

• For terrestrial organisms, the main water problem is drying out.

• Aquatic organisms

– are surrounded by water and

– face problems of water balance if their own solute concentration does not match that of their surroundings.


Figure 18.8

(a) Scales on a basilisk lizard

(b) Beaded water droplets

Figure 5.14

Animal cell

Plant cell

Normal

Flaccid (wilts)

Lysing

Turgid (normal)

Shriveled

Shriveled

Plasmamembrane

H2OH2O H2O H2O

H2OH2OH2O H2O

(a) Isotonicsolution

(b) Hypotonicsolution

(c) Hypertonicsolution

Inorganic Nutrients

• The distribution and abundance of plants are often determined by the

– availability of inorganic nutrients such as nitrogen and phosphorus and

– the structure, pH, and nutrient content of the soil.


• In many aquatic ecosystems, the growth of algae and photosynthetic bacteria is often limited by levels of

– nitrogen and

– phosphorus.

Inorganic Nutrients


Other Aquatic Factors

• Aquatic but not terrestrial ecosystems are more limited by

– the levels of dissolved oxygen,

– salinity,

– currents, and

– tides.


Other Terrestrial Factors

• Terrestrial but not aquatic ecosystems are more limited by

– wind,

– storms, or

– fire.


The Evolutionary Adaptations of Organisms

• The ability of organisms to live in Earth’s diverse environments demonstrates the close relationship between the fields of

– ecology and

– evolutionary biology.

• Evolutionary adaptation via natural selection results from the interactions between

– organisms and

– their environments.


Adjusting to Environmental Variability

• The abiotic factors in a habitat may vary

– from year to year,

– seasonally, or

– over the course of a day.


• Birds may adjust to cold by

– migrating to warmer regions (a behavioral response),

– growing heavier feathers (an anatomical response), or

– fluffing up their feathers to trap more heat (a physiological response).



Figure 18.9

• These responses, which occur during the lifetime of an individual, do not qualify as evolution, which is change in a population over time.



• Acclimation is

– gradual,

– reversible, and

– a physiological adjustment to an environmental change.

Physiological Responses


• The ability to acclimate is generally related to the range of environmental conditions a species naturally experiences.

• Among vertebrates,

– birds and mammals can tolerate the greatest temperature extremes because they are endotherms, while

– ectothermic reptiles can only tolerate a more limited range of temperatures.

Physiological Responses


Figure 18.10

Number of lizard species

Key

1–5 0 6–10 11–15 16–20 20

Anatomical Responses

• Many organisms respond to environmental challenges with some type of change in

– body shape and

– structure.

• Reversible change, such as a heavier fur coat in response to cold, is an example of acclimation.


Figure 18.11

• Environmental variation can irreversibly affect

– growth and

– development.

Anatomical Responses


Figure 18.12

Behavioral Responses

• In contrast to plants, most animals can respond to an unfavorable change in the environment by moving to a new location.

– Ectotherms may shuttle between sun and shade.

– Migratory birds travel great distances in response to changing seasons.

– Humans have an especially rich range of behavioral responses.


Figure 18.13

BIOMES

• A biome is

– a major terrestrial or aquatic life zone,

– characterized by

– vegetation type in terrestrial biomes or

– the physical environment in aquatic biomes.


• Aquatic biomes

– occupy roughly 75% of Earth’s surface and

– are determined by their

– salinity and

– other physical factors.

BIOMES


• Freshwater biomes

– have a salt concentration of less than 1% and

– include lakes, streams, rivers, and wetlands.

• Marine biomes

– typically have a salt concentration around 3% and

– include oceans, intertidal zones, coral reefs, and estuaries.

BIOMES


• Freshwater biomes

– cover less than 1% of Earth,

– contain a mere 0.01% of its water,

– harbor about 6% of all described species, and

– are used for

– drinking water,

– crop irrigation,

– sanitation, and

– industry.

Freshwater Biomes


• Freshwater biomes fall into two broad groups:

1. standing water, which includes lakes and ponds, and

2. flowing water, such as rivers and streams.

Freshwater Biomes


Lakes and Ponds

• Standing bodies of water range from small ponds to large lakes, such as North America’s Great Lakes.


Figure 18.14

• In lakes and large ponds, the communities of plants, algae, and animals are distributed according to the

– depth of water and

– distance from shore.

Lakes and Ponds


Figure 18.15

Aphoticzone

Photiczone

Benthic realm

• The photic zone, named because light is available for photosynthesis, includes

– the shallow water near shore and

– the upper layer of water away from shore.

Lakes and Ponds


• The aphotic zone

– is deeper and

– has light levels too low to support photosynthesis.

Lakes and Ponds


• The benthic realm is

– at the bottom of all aquatic biomes,

– made up of sand and organic and inorganic sediments, and

– occupied by communities of organisms that are collectively called benthos.

Lakes and Ponds


• The amount of phytoplankton growth in a lake or pond is typically regulated by the nutrients

– nitrogen and

– phosphorus.

Lakes and Ponds


Rivers and Streams

• Rivers and streams

– are bodies of water flowing in one direction and

– generally support quite different communities of organisms than lakes and ponds.


Figure 18.16

• Near the source of a stream, the water is usually

– clear,

– cold,

– swift, and

– low in nutrients.

Rivers and Streams


• Downstream, the water is usually

– murkier,

– warmer,

– slower, and

– higher in nutrients.

Rivers and Streams


• Many streams and rivers have been affected by pollution from human activities and dams to

– control floods,

– provide reservoirs for drinking water, or

– generate hydroelectric power.

Rivers and Streams


Figure 18.17

Dam

Seattle

Portland

Canada U.S.

WA MT

ID OR

NV CA

N

Snake River

River

Riv

er

umbCol ia

Will

amet

te

FlatheadLake

Wetlands

• A wetland is a transitional biome between

– an aquatic ecosystem and

– a terrestrial one.

• Wetlands

– support the growth of aquatic plants and

– are rich in species diversity.


Figure 18.18

Marine Biomes

• Marine biomes are diverse, ranging from vivid coral reefs to perpetually dark realms in the deepest regions.

• As in freshwater biomes, the seafloor is known as the benthic realm.

• The pelagic realm includes all of the open water of the oceans.


Figure 18.19

Hightide

Benthic realm

Pelagic realm

Lowtide

OarweedSeastar

Intertidalzone

Continental shelf

Sea pen

Sea spider

Brittle star

Glass sponge

Sponges

Brain coral

Phytoplankton Zooplankton

Man-of-war

Blue shark

Sperm whale

Hatchet fish

Rat-tail fish

Octopus

Gulpereel

Turtle

Seacucumber

Tripodfish

Anglerfish

Photiczone

Aphoticzone

6,000–10,000 m

1,000 m

200 m

No light

“Twilight”

• In shallow areas such as the submerged parts of continents, called continental shelves, the photic zone includes pelagic and benthic regions.

• In these sunlit areas, photosynthesis by phytoplankton and multicellular algae provides energy for a diverse community of animals.

Marine Biomes


• The pelagic photic zone includes

– zooplankton (free-floating animals, including many microscopic ones),

– fishes, and

– marine mammals.

Marine Biomes


• The coral reef biome occurs

– in the photic zone of warm tropical waters,

– in scattered locations around the globe.

Marine Biomes


Figure 18.20

• The photic zone extends down a maximum of 200 m in the ocean.

• The region between 200 and 1,000 m is

– dimly lit, sometimes called the twilight zone, and

– dominated by a fascinating variety of small fish and crustaceans.

• Below 1,000 m, the ocean is completely dark.

Marine Biomes


• The intertidal zone is where

– the ocean meets land,

– the shore is pounded by waves during high tide, and

– the bottom is exposed to the sun and drying winds during low tide.

Marine Biomes


Figure 18.21

• Estuaries

– are a transition area between a river and the ocean,

– have a saltiness ranging from nearly that of fresh water to that of the ocean, and

– are among the most productive areas on Earth.

Marine Biomes


Figure 18.22

• Estuaries are threatened by

– landfills,

– nutrient pollution,

– contamination by pathogens or toxic chemicals, such as the massive Deepwater Horizon oil spill in the Gulf of Mexico in 2010, and

– alteration of freshwater inflow.

Marine Biomes


How Climate Affects Terrestrial Biome Distribution

• Terrestrial biomes are primarily determined by climate, especially

– temperature and

– rainfall.

• Earth’s global climate patterns are largely the result of

– the input of radiant energy from the sun and

– the planet’s movement in space.


Figure 18.23

Low angle ofincoming sunlight

Sunlight strikesmost directly

Low angle ofincoming sunlight

60º N

60º S

Tropic of Capricorn

30º S

30º N Tropic of Cancer

0º (equator)

Atmosphere Antarctic Circle

Arctic Circle

• Heated by the direct rays of the sun, air at the equator

– rises,

– then cools, forming clouds, and

– drops rain.

• This largely explains why rain forests are concentrated in the tropics, the region from the Tropic of Cancer to the Tropic of Capricorn.



Figure 18.24

Descendingdry airabsorbsmoisture

Descendingdry airabsorbsmoisture

Ascendingmoist airreleases

moisture

Temperatezone

Temperatezone

Tropics

Doldrums0º

30º30º23.5º23.5º

Trade winds Trade winds

• Temperate zones generally have milder climates than the tropics or the polar regions. They occur in latitudes between

– the tropics and the Arctic Circle in the north and

– the tropics and the Antarctic Circle in the south.



• Climate is also affected by

– proximity to large bodies of water and

– the presence of landforms such as mountain ranges.



• Mountains affect climate in two major ways.

– First, air temperature drops as elevation increases.

– This results in several biomes moving up a tall mountain.



Figure 18.25

Spruce-fir forest

Desert grassland

Oak woodland

Pine woodland

Desert 3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

Ele

vati

on

(ft

)

– Second, mountains can

– block the flow of cool, moist air from a coast and

– cause radically different climates on opposite sides of a mountain range.



Figure 18.26

PacificOcean

Winddirection

CoastRange

SierraNevada

Rain shadow

East

Desert

Terrestrial Biomes

• Terrestrial ecosystems are grouped into biomes primarily on the basis of their vegetation type.


Figure 18.27

Temperate broadleaf forest

Coniferous forestArctic tundraHigh mountains (coniferous forest andalpine tundra)Polar ice

Tropical forest

Temperate grassland

Chaparral

DesertSavanna

Key

Tropic of Capricorn

30º N

Equator

30º S

Tropic of Cancer

• A climograph is a visual representation of the differences in

– precipitation and

– temperature ranges that characterize terrestrial biomes.

Terrestrial Biomes


Figure 18.28


Coniferous forest

Tundra Temperate grassland

Key

Annual mean precipitation (cm)

Tropical forest

Desert

An

nu

al m

ea

n t

em

pe

ratu

re (

ºC)

4003002001000

0

15

30

−15

• Tropical forests occur in equatorial areas, where

– the temperature is warm, and

– days are 11–12 hours long year-round.

Tropical Forest


Figure 18.29

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Tropical Rainforest

• Savannas

– are dominated by grasses and scattered trees,

– are warm year-round, and

– experience rainfall of 30–50 cm (roughly 12–20 inches per year) with dramatic seasonal variation.

Savanna


Figure 18.30

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Fir

e

Savanna

Figure 18.30a

• Deserts

– are the driest of all biomes,

– are characterized by low and unpredictable rainfall of less than 30 cm (about 12 inches) a year, and

– may be very hot or very cold.

Desert


Figure 18.31

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Desert

• Chaparral has a climate that results from cool ocean currents circulating offshore and producing

– mild, rainy winters and

– hot, dry summers.

Chaparral


Figure 18.32

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Chaparral

Fir

e

• Temperate grasslands

– are mostly treeless,

– have 25–75 cm (10–30 inches) of rain per year,

– experience frequent droughts and fires, and

– are characterized by grazers including bison and pronghorn in North America.

Temperate Grassland


Figure 18.33

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Temperate grassland

Fir

e

• Temperate broadleaf forest

– occurs throughout midlatitudes where there is sufficient moisture to support the growth of large trees, ranging from 75 to 150 cm (30 to 60 inches), and

– includes dense stands of deciduous trees in the Northern Hemisphere.

Temperate Broadleaf Forest


• Deciduous trees drop their leaves before winter, when

– temperatures are too low for effective photosynthesis and

– water lost by evaporation is not easily replaced from frozen soil.

Temperate Broadleaf Forest


Figure 18.34

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion


• Coniferous forests

– are dominated by cone-bearing evergreen trees and

– include the northern coniferous forest, or taiga, the largest terrestrial biome on Earth.

Coniferous Forest


Figure 18.35

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Coniferous forest

• Temperate rain forests

– are found along coastal North America from Alaska to Oregon and

– are also coniferous forests.

Coniferous Forest


• Tundra

– covers expansive areas of the Arctic between the taiga and polar ice and

– is characterized by

– permafrost (permanently frozen subsoil),

– bitterly cold temperatures, and

– high winds.

Tundra


Figure 18.36

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Tundra

• Polar ice covers the land

– at high latitudes north of the arctic tundra in the Northern Hemisphere and

– in Antarctica in the Southern Hemisphere.

• Only a small portion of these landmasses is free of ice or snow, even during the summer.

Polar Ice


Figure 18.37

Tem

per

atu

rera

ng

e

Pre

cip

itat

ion

Polar Ice

• All parts of the biosphere are linked by the global water cycle.

• Human activities that affect the global water cycle include

– destruction of forests and

– pumping large amounts of groundwater to the surface for irrigation.

The Water Cycle


Figure 18.38

Oceans

Precipitation Evaporation

Water vapor

Precipitation

Water vapor

Solarheat

Flow ofwater fromland to sea

Surfacewater and

groundwater

Evaporationand

transpiration

Netmovement ofwater vapor

• Sustainability is the goal of developing, managing, and conserving Earth’s resources in ways that meet the needs of people today without compromising the ability of future generations to meet their needs.

Human Impact on Biomes


• Satellite photos of a small area in Brazil show how thoroughly a landscape can be altered in a short amount of time.

Forests


Figure 18.39

In 1975, the forest in this remoteregion was virtually intact.

Same area in 2001, after a pavedhighway through the region.

• Every year, more and more forested land is cleared for agriculture.

Forests


Figure 18.40

• The impact of human activities on freshwater ecosystems may pose an even greater threat to life on Earth, including ourselves, than the damage to terrestrial ecosystems.

Fresh Water


• Las Vegas, the population center of Clark County, Nevada, is one example of a city whose water resources are increasingly stressed by drought and overuse.

• The water level in Lake Mead has

–dropped drastically and

–parched cities and farms farther downstream, which are pleading for more water.

Fresh Water


Figure 18.41

(a) May 1973 (b) May 2000

Figure 18.42

• Global climate patterns are changing because of rising concentration in the atmosphere of

– carbon dioxide (CO2) and

– certain other gases.

GLOBAL CLIMATE CHANGE


• Greenhouse gases

– include CO2, water vapor, and methane,

– are transparent to solar radiation,

– absorb or reflect heat, and

– contribute to increases in global temperatures in what is often called the greenhouse effect.

The Greenhouse Effect and Global Warming

Blast Animation: The Greenhouse Effect


Figure 18.43a

Radiant heattrapped bygreenhouse

gases

Some heatenergy escapes

into space

Atmosphere

Sunlight

Figure 18.43b

• The largest increases are in

– the northernmost regions of the Northern Hemisphere and

– parts of Antarctica.

The Greenhouse Effect and Global Warming


Figure 18.44

4.1

AntarcticPeninsula

4210.50.2−4 −2 −1 −0.5 −0.2−4.1

• The vast majority of scientists are confident that human activities have caused the rising concentrations of greenhouse gases.

The Accumulation of Greenhouse Gases


Figure 18.45

Year200015001000500

400

300

350

2500

Ca

rbo

n d

ioxi

de

(C

O2)

(pp

m)

• Overall, the uptake of CO2 by photosynthesis roughly equals the release of CO2 by cellular respiration.

• However,

– extensive deforestation has significantly decreased the incorporation of CO2 into organic material and

– CO2 is flooding into the atmosphere from the burning of fossil fuels and wood.

The Accumulation of Greenhouse Gases


Figure 18.46

Ocean

Atmosphere

Respiration

Combustion offossil fuels

Photo-synthesis

The Process of Science: How Does Climate Change Affect Species Distribution?

• Observations:

– The average temperature in Europe has risen 0.8ºC.

– Butterflies are sensitive to temperature change.

• Question: Have the ranges of butterflies changed in response to the temperature changes?


• Hypothesis: Butterfly range boundaries are shifting in line with the warming trend.

• Prediction:

– Butterfly species will establish new populations to the north of their former ranges.

– Butterfly populations at the southern edges of their ranges will become extinct.



• Experiment: Historical data on the ranges of 35 species of butterflies in Europe were analyzed.

• Results:

– More than 60% of the species have pushed their northern range boundaries poleward over the last century, some by as much as 150 miles.

– The southern boundaries have simultaneously contracted for some species, but not for others.



Figure 18.47

Norway

Denmark

SwedenFinland

RussiaEstonia

Latvia

Lithuania

Africa

Europe

Argynnis paphia (silver-washed fritillary butterfly)

Figure 18.47a

Europe

Africa

Figure 18.47b

Norway

Denmark

SwedenFinland

RussiaEstonia

Latvia

Lithuania

Figure 18.47c

Argynnis paphia (silver-washed fritillary butterfly)

Effects of Climate Change on Ecosystems

• In many plants and animals, life cycle events are triggered by

– warming temperatures or

– day length.


• As global temperatures warm, and day length remains steady, natural interactions may become out of sync.

– The winter white fur of snowshoe hares may be conspicuous against a greening landscape.

– Plants may bloom before pollinators have emerged.



• The combined effects of climate change on forest ecosystems in western North America have spawned catastrophic wildfire seasons.



Figure 18.48

• Warmer weather helps bark beetles

– bore into drought-stressed conifers and

– reproduce twice a year instead of just once.



Figure 18.49

Looking to Our Future

• Emissions of greenhouse gases continue to rise.

• In the United States, for example, total emissions increased more than 13% from 1990 to 2008.

• At this rate, further climate change is inevitable.


• The amount of greenhouse gas emitted as the result of the actions of a single individual is that person’s carbon footprint.

• We can reduce our carbon footprints by

– reducing our use of electricity,

– driving less, and

– recycling.



Figure 18.50

• In addition, eating locally grown fresh foods may lower the greenhouse gas emissions that result from food processing and transportation.



Figure 18.51

Evolution Connection: Climate Change as an Agent of Natural Selection

• Can evolutionary adaptations counteract the negative effects of climate change on organisms?

• The species most likely to adapt have

– high genetic variability and

– short life spans.


Figure 18.52

(a) Pitcher plant mosquito

(b) Adélie penguin

Figure 18.UN01

Ecosystem ecology

Organismalecology

Population ecology Community

ecology

Figure 18.UN02

Mean annual precipitation (cm)

400300200100

0

15

30M

ea

n a

nn

ua

l te

mp

era

ture

(ºC

) a. b. c.

d.

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Ecology and the Biosphere