NETA PowerPoint® Slides - WordPress.com · Title: Miller LITE 4ce_PPT_Ch09_edited Author: Maria Morlin Created Date: 1/3/2020 6:05:12 PM

1/3/20

1

Copyright © 2017 by Nelson Education Ltd.

NETA PowerPoint® Slidesto accompany

prepared byIan Dawe


Chapter 9

Population Ecology

1/3/20

2


Key Concepts

Species response to environmental stress– Population size, density, makeup,

and distribution

Species reproductive patternsSpecies genetics influence population size and survivalHuman impacts on ecosystems

3


Population Dynamics

Changes in population characteristics in response to environmental stress

• Size (number of individuals)• Density (individuals per area)• Age distribution

4

1/3/20

3


Population Dispersion

(a) Clumped (e.g., reindeer)

(b) Uniform(e.g., birds nesting in a colony)

(c) Random(e.g., dandelions)

5


Factors Governing Population Size

Age distribution– Reproductive stage

Biotic potentialEnvironmental resistance– Resource limits– Competition– Predation

6

1/3/20

4


Ecological Trade-Offs

7


Exponential vs. Logistic Population Growth

8

1/3/20

5


Logistic Growth: Tasmanian Sheep

9


Exponential Growth, Overshoot, Population Crash

10

1/3/20

6


Population Density Affects Growth — Sometimes

Density-independent controls– For example, weather events, fire, habitat

destruction

Density-dependent controls– For example, competition, predation,

infection

11


Natural Population Curves

12

1/3/20

7


Predator-Prey Relationship Controls Population Size

13

Source: Data from D. A. MacLulich


How Do Species Reproduce?

Asexual reproductionSexual reproduction:Advantages– Genetic diversity– Males hunt, gather,

protect

Disadvantages– Males cannot give birth– Genetic errors– Courtship and mating

require time and risk

14

1/3/20

8


What Reproductive Patterns Do Species Have?

r-selected species– High rate of population

increase– Opportunist species

K-selected species– Low rate of population

increase– Competitor species

15

(bea

r) ©

Tip

lyas

hina

Evg

eniy

a/Sh

utte

rsto

ck;

(mou

se) ©

Jef

frey

B. B

anke

/Shu

tters

tock


What Reproductive Patterns Do Species Have?

16

1/3/20

9


Survivorship Curves

17

© J

effre

y B.

Ban

ke/S

hutte

rsto

ck


Effects of Genetic Variations on Population Size

Can have greatest affect on small, isolated populationsLoss of genetic diversity due to:– Founder effect– Demographic bottleneck– Genetic drift– InbreedingMetapopulation interactions aid in survival of small populations

18

1/3/20

10


Human Impacts on Natural Systems

Habitat degradation and fragmentationEcosystem simplificationUse and waste of primary resourcesGenetic resistancePredator eliminationIntroduction of non-native speciesOverharvesting renewable resourcesInterference with ecological systemsCreating fossil fuel dependent systems

19


Human Footprint on the Land

20

Source: Data from Wildlife Conservation Society and the Center for International Earth Science Information Network at Columbia University (CIESIN). Reprinted by permission.

1/3/20

11


How Can We Live More Sustainably?

21


How Can We Live More Sustainably?

22

1/3/20

12


Growth of Whooping Crane Population

After falling to a population size of 22 in 1941, population has been growingApproaching wetland carrying capacityNumbers good, but flocks are still relatively small and isolated

23

Source: Data from the International Crane Foundation and the U.S. Fish &Wildlife Service


Conclusion

Population size and growth are determined by a number of factors.Environment imposes limits on population size.Populations can interact.At-risk populations can bounce back with good management.

24

Documents

NETA PowerPoint® Slides - WordPress.com · Title: Miller LITE 4ce_PPT_Ch09_edited Author: Maria Morlin Created Date: 1/3/2020 6:05:12 PM