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Ecology - Study of interactions among organisms and their environment PowerPoint PPT Presentation


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Ecology - Study of interactions among organisms and their environment. Conservation biology, environmentalism: preservation of natural world. Biosphere Ecosystems Community Population. ECOSYSTEM LEVEL Eucalyptus forest. COMMUNITY LEVEL All organisms in eucalyptus forest.

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Ecology - Study of interactions among organisms and their environment

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Ecology - Study of interactions among organisms and their environment

Conservation biology, environmentalism:

preservation of natural world


  • Biosphere

  • Ecosystems

  • Community

  • Population

ECOSYSTEM LEVELEucalyptus forest

COMMUNITY LEVELAll organisms ineucalyptus forest

POPULATION LEVELGroup of flying foxes

ORGANISM LEVELFlying fox

Brain

Spinal cord

ORGAN SYSTEM LEVELNervous system

ORGAN LEVELBrain

Nerve

TISSUE LEVELNervous tissue

CELLULAR LEVELNerve cell

MOLECULAR LEVELMolecule of DNA

Figure 1.1


Population Ecology

  • Population- how to measure?

  • Growth rates: J shaped, S shaped

  • K, r, and reproductive strategies

  • Human population


How are populations measured?

  • Population density = number of individuals in a given area or volume

  • count all the individuals in a population

  • estimate by sampling


  • mark-recapture method depends on likelihood of recapturing the same individual

Figure 35.2A


  • The dispersion pattern of a population refers to the way individuals are spaced within their area

  • Clumped -

  • Uniform:

  • Random: no pattern


Figure 35.2C


How do populations grow?

  • Idealized models describe two kinds of population growth

    1. exponential growth

    2. logistic growth


  • A J-shaped growth curve, described by the equation G = rN, is typical of exponential growth

    • G = the population growth rate

    • r = the intrinsic rate of increase, or an organism's maximum capacity to reproduce

    • N = the population size

  • King’s chess game


Figure 35.3A


high intrinsic

rate of increase

1500

r = 0.06

1000

low intrinsic

rate of increase

r = 0.02

Population size

zero population

growth

500

r = 0

negative intrinsic

rate of increase

r = -0.05

0

0

5

10

15

20

Time (years)


K = Carrying capacity is the maximum population size that an environment can support

2. Logistic growth is slowed by population-limiting factors

Figure 35.3B


  • K = carrying capacity

  • The term (K - N)/Kaccounts for the leveling off of the curve

  • logistic growth curve

Figure 35.3C


Multiple factors may limit population growth

declining birth rate or increasing death rate

  • The regulation of growth in a natural population is determined by several factors

    • limited food supply

    • the buildup of toxic wastes

    • increased disease

    • predation


  • About every 10 years, both hare and lynx populations have a rapid increase (a "boom") followed by a sharp decline (a "bust")

Figure 35.5


  • Three types of survivorship curves reflect important species differences in life history

  • Survivorship curves plot the proportion of individuals alive at each age

Figure 35.6


Evolution shapes life histories

  • An organism's life history is the series of events from birth through reproduction to death

  • Life history traits include

    • the age at which reproduction first occurs

    • the frequency of reproduction

    • the number of offspring

    • the amount of parental care given

    • the energy cost of reproduction


  • Principles of population ecology may be used to

    • manage wildlife, fisheries, and forests for sustainable yield

    • reverse the decline of threatened or endangered species

    • reduce pest populations

    • IPM = Integrated Pest Management


  • Integrated pest management (IPM) uses a combination of biological, chemical, and cultural methods to control agricultural pests

  • IPM relies on knowledge of

    • the population ecology of the pest

    • its associated predators and parasites

    • crop growth dynamics


The Spread of Shakespeare's Starlings

  • In 1890, a group of Shakespeare enthusiasts released about 120 starlings in New York's Central Park


Current

  • Today: over 100 million starlings, spread over N. Amer.

1955

Current

1955

1945

1935

1925

1945

1905

1915

1925

1935

1925

1935


  • The starling population in North America has some features in common with the global human population

  • Both are expanding and are virtually uncontrolled

  • Both are harming other species


THE HUMAN POPULATION

  • doubled three times in the last three centuries

  • about 6.1 billion and may reach 9.3 billion by the year 2050

  • improved health and technology have lowered death rates


  • The history of human population growth

Figure 35.8A


RAPID GROWTH

SLOW GROWTH

ZERO GROWTH/DECREASE

Kenya

United States

Italy

Male

Female

Male

Female

Male

Female

  • The age structure of a population is the proportion of individuals in different age-groups

Ages 45+

Ages 45+

Ages 15–44

Ages 15–44

Under15

Under15

Percent of population

Percent of population

Percent of population

Also reveals social conditions, status of women

Figure 35.9B


  • The ecological footprint represents the amount of productive land needed to support a nation’s resource needs

  • The ecological capacity of the world may already be smaller than its ecological footprint


  • Ecological footprint in relation to ecological capacity

Figure 35.8B


Per capita CO2 emissions

(metric tons of carbon)

Total CO2 emissions

(billion metric tons of carbon)

0

1

2

3

4

5

6

0

0.5

1

1.5

U.S.

U.S.

5.48

1.49

China

China

0.75

0.91

0.39

Russia

2.65

Russia

Japan

Japan

2.51

0.32

India

0.29

India

0.28


  • What next?

Figure 35.8C


Figure 2.10x


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