Chapter 34 and 36

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings

PowerPoint Lectures forBiology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon

Lectures by Chris Romero

Chapter 34Chapter 34

The Biosphere: An Introduction to Earth’s Diverse Environments


A Mysterious Giant of the Deep

• There are about 1,000 known species of squid

– But until recently, no one had reported on this “mystery squid”


• Deep-sea submersibles

– Are allowing scientists to study uncharted depths of the ocean

Figure A


• At depths of up to 2,500 meters

– Scientists are observing new environments and a great variety of organisms

Figure B Figure C


• Ecology

– Is the scientific study of the interactions of organisms with their environments


34.1 Ecologists study how organisms interact with their environment at several levels

• At the organismal level

– Ecologists may examine how one kind of organism meets the challenges of its environment

Figure 34.1


• At the population level

– Ecologists might study factors that limit population size

• At the community level

– An ecologist might focus on interspecies interactions


• Ecosystem interactions involve

– Living (biotic) communities and nonliving (abiotic) physical and chemical factors


THE BIOSPHERE

34.2 The biosphere is the total of all of Earth’s ecosystems

• The biosphere

– Is the global ecosystem

Figure 34.2A


• Patchiness of the environment

– Characterizes the biosphere

Figure 34.2B


CONNECTION

34.3 Environmental problems reveal the limits of the biosphere

• Human activities, including the widespread use of chemicals

– Affect all parts of the biosphere


• Rachel Carson, a famous ecologist

– Was one of the first people to perceive the global dangers of pesticide use

Figure 34.3


34.4 Physical and chemical factors influence life in the biosphere

• Abiotic factors determining the biosphere’s structure and dynamics include

– Solar energy, water, temperature, wind, and disturbances

Figure 34.4


34.5 Organisms are adapted to abiotic and biotic factors by natural selection

• Unique adaptations

– Allow the survival of organisms in particular habitats

Figure 34.5


• Biotic factors, such as predation and competition

– Can lead to the evolution of adaptations by natural selection


34.6 Regional climate influences the distribution of biological communities

• Most climatic variations

– Are due to the uneven heating of Earth’s surface as it orbits the sun

Low angle ofincoming sunlight

Sunlight strikesmost directly

Low angle of incoming sunlight

Atmosphere

60ºSSouth Pole

Tropic ofCapricorn30ºS

0º (equator)

30ºNTropic ofCancer

North Pole60ºN

Figure 34.6A


• The tilt of the Earth’s axis

– Causes the changes of the seasons in the northern and southern hemispheres

June solstice(Northern

Hemisphere tiltstoward sun)

March equinox(equator facessun directly)

Constant tiltof 23.5º

Septemberequinox

Decembersolstice(Northern

Hemisphere tiltsaway from sun)

Figure 34.6B


• The uneven heating of the Earth

– Also sets up patterns of precipitation and prevailing winds

Descendingdry airabsorbsmoisture Trade winds

Ascendingmoist airreleasesmoisture

Trade winds

Descendingdry airabsorbsmoisture

Doldrums

Temperatezone

TropicsTemperate

zone

30º23.5º 0º 23.5º

30º

60ºN

30ºN

30ºS

Figure 34.6C, D


• Ocean currents

– Influence coastal climateFresno104º

Paso Robles93º Bakersfield

106º

DeathValley119º

Pacific Ocean

Santa Barbara 75º

Los Angeles(Airport) 74º

San Diego 75º

40 miles

San Bernardino 101º

Riverside 91º

Palm Springs 104º

Burbank86º

Santa Ana84º

Key70s (ºF)

80s

90s

100s

110s

Figure 34.6E


PacificOcean

CoastRange

Winddirection

SierraNevada

East

Figure 34.6F

• Landforms such as mountains

– Affect rainfall


AQUATIC BIOMES

34.7 Oceans occupy most of Earth’s surface

• Several characteristics shape ocean communities

– Light, distance from shore, and the availability of nutrients


• The intertidal zone, an oceanic zone

– Is the area of shore where the ocean meets the land

Figure 34.7A


• Oceanic zones also include

– The pelagic and benthic zonesIntertidal zone

Photic zone0

200 mContinentalshelf

2,500–6,000 m

Benthic zone(seafloor)

Pelagiczone

Aphoticzone

Figure 34.7B


• Coral reefs

– Are found in warm waters above continental shelves

Figure 34.7C


• Estuaries

– Are productive areas where rivers flow into the ocean

Figure 34.7D


34.8 Freshwater biomes include lakes, ponds, rivers, streams, and wetlands

• Factors that shape lake and pond communities include

– Light, temperature, and the availability of nutrients and dissolved oxygen


• Abiotic factors change from the source of a river to its mouth

– And communities vary accordingly

Figure 34.8A


• Wetlands include

– Marshes and swamps

Figure 34.8B


TERRESTRIAL BIOMES

34.9 Terrestrial biomes reflect regional variations in climate

• Temperature and rainfall

– Mainly determine the terrestrial biomes


• Major terrestrial biomes

30ºN

Tropic ofCancer

Equator

Tropic ofCapricorn

30ºS

Tropical forest

SavannaDesertChaparral

Temperate grassland

Temperate broadleaf forestConiferous forest

Tundra

High mountains

Polar ice

Figure 34.9


34.10 Tropical forests cluster near the equator

• Tropical rain forests

– Are the most diverse ecosystem

Figure 34.10


34.11 Savannas are grasslands with scattered trees

• Savannas

– Are dry and warm

Figure 34.11


34.12 Deserts are defined by their dryness

• Deserts

– Are the driest biomes

Figure 34.12


34.13 Spiny shrubs dominate the chaparral

• The chaparral

– Is a shrubland with cool, rainy winters and dry, hot summers

Figure 34.13


34.14 Temperate grasslands include the North American prairie

• Temperate grasslands

– Are found where winters are cold

Figure 34.14


34.15 Broadleaf trees dominate temperate forests

• Temperate broadleaf forests grow throughout midlatitude regions

– Where there is sufficient moisture to support the growth of large trees

Figure 34.15


34.16 Coniferous forests are often dominated by a few species of trees

• The northern coniferous forest, or taiga

– Is found where there are short summers, and long, snowy winters

Figure 34.16


34.17 Long, bitter-cold winters characterize the tundra

• Arctic tundra

– Is a treeless biome characterized by extreme cold, wind, and permafrost

Figure 34.17


• Alpine tundra

– Occurs above the treeline on high mountains


TALKING ABOUT SCIENCE

34.18 Ecologist Ariel Lugo studies tropical forests in Puerto Rico

• The Luquillo Experimental Forest

– Allows ecologists to study the effects of disruption on tropical forests

Figure 34.18A, B


PowerPoint Lectures forBiology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon

Lectures by Chris Romero

Chapter 36Chapter 36

Population Dynamics


The Spread of Shakespeare’s Starlings

• The European Starling

– Has become an abundant and destructive pest in North America

Europeanstarling


• Starling populations have become very successful

– And spread throughout North America since their introduction in 1890

Current

1955

1945

1935 1925

19151905

19251935

1945

1955Current

The spread of starlings across North America


• Population ecology

– Is concerned with changes in population size and the factors that regulate populations over time


36.1 Population ecology is the study of how and why populations change

• A population

– Is a group of individuals of a single species that occupy the same general area


POPULATION STRUCTURE AND DYNAMICS

36. 2 Density and dispersion patterns are important population variables

• Population density

– Is the number of individuals of a species per unit of area or volume


• Environmental and social factors

– Influence the spacing of individuals in various dispersion patterns: clumped, uniform, or random

Figure 36.2A Figure 36.2B


36.3 Life tables track mortality and survivorship in populations

• Life tables and survivorship curves

– Predict an individual’s statistical chance of dying or surviving during each interval of the individual’s lifetime

Table 36.3


• The three types of survivorship curves

– Reflect species’ differences in reproduction and mortality

Pe

rce

nta

ge

of

surv

ivo

rs (

log

sca

le) 100

10

1

0.10 50 100

III

II

I

Percentage of maximum life spanFigure 36.3


36.4 Idealized models help us understand population growth


The Exponential Growth Model

• Exponential growth

– Is the accelerating increase that occurs when growth is unlimited


• The equation G rN describes this J-shaped curve

– G the population growth rate

– r an organism’s inherent capacity to reproduce

– N the population size

Figure 36.4A

Time Number of Cells

0 minutes

20

40

60

80

100

120 (= 2 hours)

3 hours

4 hours

8 hours

12 hours

1

2

4

8

16

32

64

512

4,096

16,777,216

68,719,476,736

= 20

= 21

= 22

= 23

= 24

= 25

= 26

= 29

= 212

= 224

= 236

Num

ber

of b

acte

rial c

ells

(N

)

70

60

50

30

40

20

10

00 20 40 60 80 100 120 140

G = r N

Time (min)


Limiting Factors and the Logistic Growth Model

• Limiting factors

– Are environmental factors that restrict population growth

Bre

edin

g m

ale

fur

seal

s(t

hous

ands

)10

8

6

4

2

01915 1925 1935 1945

YearFigure 36.4B


• Logistic growth

– Is the model that represents the slowing of population growth as a result of limiting factors

– Levels off at the carrying capacity, which is the number of individuals the environment can support

Nu

mb

er

of

ind

ivid

ua

ls (

N)

K

0Time

G = r N

G = r N(K – N)

K

Figure 36.4C


• The equation G rN(K – N)/K describes a logistic growth curve

– Where K carrying capacity and (K – N)/K accounts for the leveling off of the curve


36.5 Multiple factors may limit population growth

• As a population’s density increases

– Factors such as limited food supply and increased disease or predation may increase the death rate, decrease the birth rate, or both

4.0

3.6

3.8

3.4

3.2

3.0

2.80 10 20 30 40 50 60 70 80

Density of females

Clu

tch

size

Figure 36.5A


• Abiotic factors such as weather

– May limit many natural populations

Exponentialgrowth

Suddendecline

Num

ber

of

aph

ids

Apr May Jun Jul Aug Sep Oct Nov DecFigure 36.5B


• Most populations

– Are probably regulated by a mixture of factors, and fluctuations in numbers are common

Time (years)

1975 1980 1985 1990 1995 20000

20

40

80

60

Num

ber

of f

emal

es

Figure 36.5C


36.6 Some populations have “boom-and-bust” cycles

• Some populations

– Undergo regular boom-and-bust cycles of growth and decline

160

120

80

40

01850 1875 1900 1925

9

6

3

0

Snowshoe hare

Lynx

Har

e po

pula

tion

size

(tho

usan

ds)

Lynx

pop

ulat

ion

size

(tho

usan

ds)

Year Figure 36.6


36.7 Evolution shapes life histories

• An organism’s life history

– Is the series of events from birth through reproduction to death

LIFE HISTORIES AND THEIR EVOLUTION


• Populations with so-called r-selection life history traits

– Produce many offspring and grow rapidly in unpredictable environments

Figure 36.7A


• Populations with K-selected traits

– Raise few offspring and maintain relatively stable populations


• Life history traits

– Are shaped by natural selection

Experimentaltransplant ofguppies

Predator: Killifish;preys mainly on small,immature guppies

Guppies: Larger atsexual maturity thanthose in pike-cichlidpools

Predator: Pike-cichlid;preys mainly on large,mature guppies

Guppies: Smaller atsexual maturity thanthose in killifish poolsFigure 36.7B


36.8 Principles of population ecology have practical applications

• Principles of population ecology

– Are useful in managing natural resources

CONNECTION

900

800

700

600

500

400

300

200

100

01960 1970 1980 1990 2000

Yie

ld (

thou

sand

s of

met

ric t

ons)

Figure 36.8


THE HUMAN POPULATION CONNECTION

The Plague

6

5

4

3

2

1

08000B.C.

4000B.C.

3000B.C.

2000B.C.

1000B.C.

0 1000A.D.

2000A.D.

Hum

an p

opul

atio

n si

ze (

billi

ons)

Figure 36.9A

36.9 Human population growth has started to slow after centuries of exponential increase

•The human population

– Has been growing almost exponentially for centuries, standing now at about 6.4 billion


• The ecological footprint

– Represents the amount of land per person needed to support a nation’s resource needs

16

14

12

10

8

6

4

2

00 2 4 6 8 10 12 14 16

Available ecological capacity (ha per person)

Eco

log

ica

l fo

otp

rint

(ha

pe

r p

ers

on

)

Japan

UK

Spain

Germany

NetherlandsNorway

USA

World

ChinaIndia

Sweden

Canada

Australia

New Zealand

Figure 36.9B


• The ecological capacity of the world

– May already be smaller than the population’s ecological footprint

Traffic in downtown Cairo, Egypt

Manhattan,New York City

Refugee camp in ZaireFigure 36.9C


36.10 Birth and death rates and age structure affect population growth

• The demographic transition

– Is the shift from high birth rates and death rates to low birth rates and death rates

50

40

30

20

10

01900 1925 1950 1975 2000 2025 2050

Year

Birth rate

Death rate

Birt

h or

dea

th r

ate

per

1,00

0 po

pula

tion

Figure 36.10A


• The age structure of a population

– Is the proportion of individuals in different age-groups

– Affects its future growth

Age85+

80–8475–7970–7465–6960–6455–5950–5445–4940–4435–3930–3425–2920–2415–1910–145–90–4

8 46 2 0 2 4 6 8 6 4 2 0 2 4 6 6 4 2 0 2 4 6

Percent of population Percent of population Percent of population

Primaryreproductive

ages

Rapid growth Slow growth Decrease

Afghanistan United States Italy

Male Female Male Female Male Female

Figure 36.10B


• Increasing the status of women

– May help to reduce family size