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Chapter 8 Population Change

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Presentation on theme: "Chapter 8 Population Change"— Presentation transcript:

1 Chapter 8 Population Change

2 Overview of Chapter 8 Principles of Population Ecology
Factors that Effect Population Size Reproductive Strategies Metapopulations The Human Population Demographics of Countries Demographics of United States

3 Principles of Population Ecology
Study of populations and why their numbers change over time Important for Endangered species Invasive species Population Group of individuals of same species living in the same geographic area at the same time

4 Population Density Population density
The number of individuals of a species per unit area or volume at a given time Ex: minnows per Liter of pond water Ovals below have same population, and different densities

5 Change in Population Size

6 Change in Population Size

7 Calculating Population Change
Death rate Growth rate Emigration rate r = (b – d) + (i – e) Birth rate Immigration rate Birth (b), Death (d), Immigration (i) and Emigration (e) are calculated per 1000 people

8 Maximum Population Growth
Intrinsic Rate of Growth (Biotic Potential) Growth rate under ideal conditions J- Shaped Curve (exponential growth)

9 Environmental Resistance
Environmental limits (resistance) Prevent indefinite reproduction Unfavorable food, water, shelter, predation, etc. Carrying Capacity (K) Maximum # of individuals an environment can support Causes leveling off of exponential growth S-shaped curve of logistic population growth

10

11 Population Crash Overshooting carrying capacity can lead to population crash Abrupt decline in population density

12 Factors That Affect Population Size
Density Dependent Factor Factor whose effect on population changes as population density changes Examples: Predation Disease Competition Sometimes cause Boom-or-Bust Population Cycles

13 Boom-Or-Bust Population Cycles

14 Case Study- Predator Prey Dynamics on Isle Royale
As wolf population increases, moose population decreases (and vice versa)

15 Factors That Affect Population Size
Density Independent Factors Factors that affects population size, but is not influenced by changes in population density Examples: Killing frost Severe blizzard Fire

16 Reproductive Strategies
r-selected species k-selected species -Small body size - Early maturity - Short life span - Large broods - Little or no parental care Probability of long term survival is low Mosquitoes and Dandelions Small broods Long life span Slow development Large body size Late reproduction Low reproductive rate Redwood trees and human beings

17 Survivorship

18 Some populations fit two curves
Herring Gulls Type III & Type II

19 Metapopulations A set of local populations among which individuals are distributed in distinct habitat patches across a landscape Source habitats Sink habitats

20 Metapopulations

21 Human Population Demography
Science of population structure and growth Human Population since 1980 is J-shaped curve

22 Population Increase in Mexico

23 Projecting Future Populations
Population is increasing Growth rate (r) has started to decline Projections for 2050 Low = 7.7 billion High = 10.6 billion Most likely = 9.1 billion

24 Demographics of Countries

25 Demographic Stages Pre-industrial Stage Transitional Stage
Birth and death rates high, modest population growth Transitional Stage Lowered death rate, rapid population growth Industrial Stage Birth rate decline, population growth slow Post Industrial Stage Low birth and death rates, population growth very slow

26 Demographic Stages

27 Fertility Changes in Select Countries

28 Age Structure Diagrams

29 Worldwide 29% of human population is under age 15
Could cause large increase in birth rates

30 Education of Immigrants into US


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