Chapter 8 Population Change

Overview of Chapter 8

Principles of Population Ecology Factors that Affect Population Size Reproductive Strategies The Human Population Demographics

Principles of Population Ecology

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

Population Density

Population density The number of individuals of a species per unit

area or volume at a given time

Ovals below have same population, and

different densities

Change in Population Size

Change in Population Size

Growth rate

Birth rate

Death rate

Immigration rate

Emigration rate

r = (b – d) + (i – e)

Calculating Population Change

Birth (b), Death (d), Immigration (i) and Emigration (e) are calculated per 1000 people

Maximum Population Growth

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

Environmental Resistance

Environmental limits (resistance) Prevent indefinite reproduction Available 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

Population Crash

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

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

Boom-Or-Bust Population Cycles

Human Population Human population in modern age is J-shaped

curve

Population Increase in Mexico

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

Demographics of Countries

Demographics of Countries

Demographic Stages

Pre-industrial 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

Demographic Stages

Fertility Changes in Select Countries

Age Structure Diagrams

Worldwide

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

Chapter 9 Addressing Population Issues

Population and Quality of Life

Difficult to meet basic needs in developing countries

Problems associated with overpopulation: Environmental degradation Hunger Persistent poverty Economic stagnation Urban deterioration Health issues

Food insecurity In shaded countries, more than 20% of

population is undernourished

Reducing the Total Fertility Rate

Three major influences on total fertility rate 1. Cultural traditions 2. Social & economic status of women 3. Family planning

Single most important factor = low social status of women worldwide

Cultural influences: Marriage age Number of children – often

related to infant mortality rates

Whether children work in family business

Religious values and views on gender roles and birth control

Cultural Traditions

Gender inequality is common worldwide Disparities Political participation Social status Economic status Health status Legal rights Education Employment and earnings Illiteracy rates in 2002

Social & Economic Status of Women

Educational Opportunities and Fertility

Women with more education tend to: Marry later Have fewer

children

United States

Family Planning Services

Family planning services offer information to both men and women on sexuality, contraception, STDs, and parenting

Achieving Population Stabilization

How can developing country governments help? Increase funding to pubic health and family planning

services Education on methods of birth control Increase average level of education

How can developed country governments help? Provide financial support Support research and development of new birth

control methods

Chapter 10 The Urban World

Population and Urbanization

Milestone: As of 2008, half of the world’s population lives in urban areas

Characteristics of Urban Population

Basic characteristics of city populations: Diverse population in terms of race, ethnicity,

religion, and socioeconomic status Younger population than local rural area More males in developing nation cities More females in developed nation cities

Substandard Housing Typically occupied by

“squatters” – no legal ownership

No city services Water, sewage, garbage

collection, police and fire protection

1/3 of urban population in developing countries are squatters

United States Urban Agglomerations

(Population of 50,000 or above)

Urbanization Trends Urban Agglomeration Urbanized core region that consists of several

adjunct cities or megacities and their surrounding developed suburbs

Environmental Problems in Urban Areas

Growing urban areas affect land use patterns Fragment wildlife Encroach wetlands, forests, desert, etc.

Impermeable surfaces and urban runoff discharged into waterways Motor oil, lawn fertilizers, heavy metals

Noise pollution

Suburban Sprawl

Suburban Sprawl Patchwork of vacant and developed tracts around

the edges of cities

Problems Loss of wetlands Air & water pollution Loss of biological habitat

Making Cities More Sustainable

Characteristics of a sustainable city Clear, cohesive urban growth policies Reduction of pollution and waste Large areas of green space People-centers, not car-centered Food grown in or near city (rooftop gardens) Compact development

Copenhagen, Denmark A People-centered City