chp. 36 what impact did bp disaster have on the ocean ecosystem and population?? reflect on this...

Chp. 36What impact did BP disaster have

on the ocean ecosystem and population??

Reflect on this disaster….

The tale of two fish….population ecology

Read scenario p725Use population ecology to summarize this passage…

Read 36.1, 36.2, 36.4, 36.5, 36.6, 36.8, 36.11

36.1 Relate population with boundaries, population ecologist, population dynamics and population growth.

36.2 Example (other than one in the book) of population density

Example (other than ones in book) of clumped dispersion, uniform dispersion and random dispersion

36.4 Contrast exponential growth model and logistic growth model. Use per capita, limiting factors and carrying capacity, in discussion

Copyright © 2009 Pearson Education, Inc.

Introduction: A Tale of Two Fishes

• Population ecology is concerned with– Changes in population size– Factors that regulate populations over time

• It helps explain the biodiversity of an environment


• Ecologists learn the structure and dynamics of natural populations

• With this information they are better equipped to– Develop sustainable food sources– Assess the impact of human activities– Balance human needs with the conservation of

biodiversity and resources

Introduction: A Tale of Two Fishes


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

• Population– A group of individuals of a single species that occupy

the same general area

• Individuals in a population– Rely on the same resources– Are influenced by the same environmental factors– Are likely to interact and breed with one another


• A population can be described by the number and distribution of individuals

• Population dynamics is the interactions between– Biotic and abiotic factors

• It is the cause of variation in population sizes– A population increases through birth and

immigration– Death and emigration out of an area decrease the

population

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


36.2 Density and dispersion patterns are important population variables

• Population density is the number of individuals of a species per unit area or volume

• Examples of population density– The number of oak trees per square kilometer in a

forest– The number of earthworms per cubic meter in

forest soil

• Ecologists use a variety of sampling techniques to estimate population densities


• Within a population’s geographic range, local densities may vary greatly

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



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

• Dispersion patterns can be– Clumped– Uniform– Random



• In a clumped pattern individuals are grouped in patches

• Unequal distribution of resources• Mating• Social behavior

• Plants and fungi clumped in areas where soil conditions favor germination

• Flies



• In a uniform pattern individuals are equally spaced in the environment

• Territorial behavior• Interactions between individuals in same

population



• In a random pattern of dispersion, the individuals in a population are spaced in an unpredictable way

• Wind-blown seeds• Habits and social interaction make random

pattern rare


Percentage of maximum life span

Per

cen

tag

e o

f su

rviv

ors

(lo

g s

cale

)

0 50 100

0.1

1

10

100

III

II

I


36.4 Idealized models predict patterns of population growth

• Exponential growth model – The rate of population increases under ideal

conditions– Calculated using the equation G = rN

– G is the growth rate of the population– N is the population size– r is the per capita rate of increase

Time (months)

Po

pu

lati

on

siz

e (N

)

0 1 2 3 4 5 6 7 8 9 10 11 12

0

50

100

150

200

250

300

350

400

450

500


• Logistic growth model– This growth model takes into account limiting

factors– Limiting factors are environmental factors that

restrict population growth– Formula


(K N)G = rN

K

Year

Bre

edin

g m

ale

fur

seal

s(t

ho

usa

nd

s)

1915 1925 1935 19450

2

4

6

8

10


• Idealized models describe two kinds of population growth

– Exponential growth – Logistic growth


Time

Nu

mb

er o

f in

div

idu

als

(N)

0

K

G = rN

G = rN(K – N)

K

Test Weds. sections 36.1,2,4,5,6,7

Read 36.5, 36.6, 36.7 and takes notes on these sections. Make sure to include summaries of all figures….


36.5 Multiple factors may limit population growth

• The logistic growth model– Population growth slows and ceases as population

density increases– Increasing population density results in a decrease

in birth rate, an increase in death rate, or both

Density of females

Clu

tch

siz

e

0 10 20 30 40 50 60 70 802.8

3.0

3.2

3.4

3.6

3.8

4.0


• Abiotic factors may reduce population size before other limiting factors become important


Apr May Jun Jul Aug Sep Oct Nov Dec

Nu

mb

er o

f ap

hid

s

Exponentialgrowth

Suddendecline


• Most populations fluctuate in numbers


Time (years)

Nu

mb

er o

f fe

mal

es

1975 1980 1985 1990 1995 20000

20

40

60

80

Males Females

Experimentaltransplant ofguppies

Predator: Killifish; preysmainly on small guppies

Guppies:Larger atsexual maturitythan those inpike-cichlid pools

Pools with killifish,but no guppies priorto transplant

Predator: Pike-cichlid preys mainly on large guppies

Guppies: Smaller at sexual maturity thanthose in killifish pools11 years

later

Mas

s o

f g

up

pie

sat

mat

uri

ty (

mg

)

40

80

120

160

200

67.5 76.1

161.5185.6

Ag

e o

f g

up

pie

sat

mat

uri

ty (

day

s)

Males Females

20

40

60

80100

48.558.2

85.792.3 Control:Guppies from poolswith pike-cichlidsas predators

Experimental:Guppies transplantedto pools with killifishas predators

36.536.61.613.3

36.718.6


THE HUMAN POPULATION


36.9 The human population continues to increase, but the growth rate is slowing

• Human population is expected to continue increasing for several decades

• 95% of the increase is in developing nations

1500

Year

Population increase

Total population size

To

tal p

op

ula

tio

n (

in b

illio

ns

)

1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 20500

2

4

6

8

10

20

40

60

80

100

An

nu

al in

cre

ase

(in

mill

ion

s)

Year

Birth rate

Death rate

Rate of increase (r)

1900 19501925 1975 2000 2025 2050

0

10

20

30

40

50

Bir

th o

r d

eath

rat

ep

er 1

,000

po

pu

lati

on


36.11 CONNECTION: An ecological footprint is a measure of resource consumption

• U.S. Census Bureau projection– 8 billion people within the next 20 years– 9.5 billion by mid-21st century


• Ecological footprint helps understand resource availability and usage

• The United States has a– Big ecological footprint – Large ecological deficit

36.11 CONNECTION: An ecological footprint is a measure of resource consumption


You should now be able to

1. Explain the factors that determine the characteristics of a population

2. Describe exponential growth and the factors that produce logistic growth of a population

3. Explain the limiting factors that influence population growth

4. Distinguish between r- and K-strategies5. Describe and give examples of the different types of

life histories


6. Explain the factors the determine human population growth

7. Describe the concept of ecological footprint

You should now be able to

Chp. 37 Communities and Ecosystems

I will be able to relate structure and dynamics of ecosystems and

communities with how human activities can disrupt the balance

Read p741 Hungry Hippos!!

37.1 Community

Define population

chp. 36 what impact did bp disaster have on the ocean ecosystem and population?? reflect on this...

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