# Chap 5 Outline Populations

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```							Chap 5 Outline: Populations
5-1 How Populations grow
Key Concepts: What characteristics are used to describe a population?
What factors affect population size?
What are exponential growth and logistic growth?
Characteristics of Populations:
-Three important characteristics of a population are;
1) Geographic distribution: A term used to describe the area inhabited by a
population.
2) Population density: The number of individuals per unit area.
3) Growth rate: How fast a population is growing or shrinking.
Population Growth:
-Populations can grow in size, remain constant and shrink.
-Factors that affect a population are the number of birth and deaths and the rate of
immigration and emigration.
1) Immigration: The movement of individuals into a population.
2) Emigration: The movement of individuals out of a population.
Exponential Growth:
-If a population has abundant space and food and is protected from predators and
disease, the population will increase rapidly.
-Exponential Growth: Occurs when individuals reproduce at a constant rate and
forms a J-shaped curve. This occurs under ideal conditions.
1) Exponential growth can not be sustained.
Logistic Growth:
-As resources become limited growth in a population slows down.
-Logistic growth: Occurs when a population’s growth rate slows or stops after a
period of exponential growth. Forms a S-shaped curve.
-Carrying capacity: Largest number of individuals in a population that a given
environment can support.
5-2 Limits to Growth:
Key Concepts: What factors limit population growth?
Limiting Factors:
-Limiting Factor: A factor that causes population growth to decrease or to stop.
-Density-dependent limiting factors: A limiting factor that depends on the size of
a population.
1) Competition: When a population gets to big individuals compete with
each other for limited resources. Can also occur between species.
2) Predation: As the size of predator and prey populations increase and
decrease they have an effect on the other.
3) Parasitism and disease: Parasites and disease are easier spread in very
densely populated areas.
-Density-independent limiting factors: Affects all populations in similar ways
regardless of population size.
1) Unusual weather, natural disasters, seasonal cycles and human activities
are all examples of density-independent limiting factors.
2) Populations tend to crash in response to theses factors and then build
back up again overtime.
5-3 Human Population Growth:
Key concepts: How has the size of human population changed overtime?
Why do population growth rates differ in countries throughout the world?
Historical Overview:
-Like the populations of many other living organisms the size of the human
populations tends to increase with time.
1) In most developed countries the growth rate is very low (<1%)
2) In developing countries the growth rates tend to be higher (2-3%)
or 3 births/second.
-For most of human history the population has grown very slowly to very harsh
living conditions.
1) Because of this there was a very high birthrate and death rate.
2) There was also a very high infant mortality rate and short life span.
-About 500 years ago human populations started to grow much faster due to
1) Agriculture and industry
2) Improved sanitary conditions
3) Medical technology
Patterns of Population Growth:
-The human population can not undergo exponential growth forever due to
limited resources.
1) War, famine and disease can all slow and stop human pop. Growth
-Demography: The scientific study of human population growth and the social
and economic factors that affect it.
1) Birth rates, death rates, and age structures are all factors that affect
human population growth.
-Demographic Transition: A dramatic transition in the birth and death rates of a
country that tends to slow population growth.
-Age-growth structure: A diagram that depicts the relative number of males and
females and their ages in a population..
1) These can be used to determine future population growth.
Future Population Growth?
Chap 6 Outline:
6-2 Renewable and Nonrenewable Resources:
Key Concepts: How are environmental resources classified?
What affects do human activities have on natural resources?
-Tragedy of the Commons
Classifying Resources:
-Environmental goods and services are classified as renewable or nonrenewable
resources.
1) Renewable resources: Natural resources that can regenerate or replenish
themselves.
2) Nonrenewable resources: Natural resources that can not be renewed.
Sustainable Development:
-Sustainable development: A way of using natural resources w/o depleting them
or causing long term environmental harm.
1) Human activities can affect the quality and supply of renewable
resources such as land, forests, fisheries, air and fresh water.
Renewable Resources:
-Land is a resource that provides space for human communities, raw materials
for industry and soil for agriculture.
1) Plowing of land can leave soil vulnerable to soil erosion: The wearing
away of surface soil by wind and water.
2) Desertification: Combination of farming and overgrazing and drought
that can turn productive areas into desert
-Other resources include forests, fisheries, air, and water. All of these are
renewable resources as long as they aren’t overburdened.
6-3 Biodiversity:
Key concepts: What is the value of biodiversity?
What are the current threats to biodiversity?
What is the goal of conservation biology?
The Value of Biodiveristy:
-Biodiversity: Is the total variety of organisms in the biosphere.
-Ecosystem diversity: The variety of habitats, communities, and ecological
processes in the biosphere.
-Species diversity: The number of different species in the biosphere.
-Genetic diversity: Total of all different forms of genetic information.
-Biodiversity is one of earth’s greatest natural resources. Species of many kinds
have provided food industrial products and medicines.
Threats to Biodiversity:
-Human activities can reduce biodiversity by altering habitats, hunting species
nearly to extinction, pollution, and introduction of foreign species to new
environments.
1) Habitat fragmentation: Splitting of an ecosystem into pieces
2) Biological magnification: Occurs when concentrations of harmful
substances increase as you move up trophic levels.
3) Invasive species: Plants and animals that been accidentally and
intentionally introduced to places where they are not native.
Conserving Biodiversity:
-Conservation: Is used to describe the wise management of natural resources
including the preservation of wildlife and habitats.
1) Conservation efforts focus on protecting entire ecosystems as well as
single species. By protecting entire ecosystems it ensures that the
habitat as well as the interactions of many different species in that
habitat are preserved.

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