Chapter 4 Population Biology

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Chapter 4 Population Biology

• I. Population Dynamics
• A. Principles of Population Growth
• 1. A population is a group of organisms
• of the same species that live in a
• specific area.
• 2. Populations of organisms do not
• experience linear growth.
• 3. What is exponential growth?
• a. Means as the population gets
• larger, it also grows at a faster
• rate.

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• 4. What can limit growth?
• a. Limiting factors such as
  availability of food, disease,
• predators, or lack of space will
  cause a population
• growth to slow.
• 5. The number of organisms of one species
  that an
• environment can support indefinitely
  is its carrying
• capacity.
• 6. When a population overshoots the
  carrying capacity, then
• limiting factors may come into
  effect.
• 7. Deaths begin to exceed births and the
  population falls
• below carrying capacity.
• B. Reproduction Patterns
• 1. Life-history pattern is an organisms
  reproductive pattern.
• 2. Rapid life-history pattern organisms
  have a small
• body size , mature rapidly, reproduce
  early, and have
• a short life span.
• 3. Slow life-history pattern organisms
  reproduce and mature
• slowly, and are long-lived. They
  maintain population sizes
• art or near carrying capacity.

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• 4. Two limiting factors that are related
  to dispersal
• a. density-dependent factors Factors
  that are related to the
• density of a population Include
  disease, competition,
• predators, parasites, and food
• b. density-independent factors affect
  populations no matter how
• large or small Include volcanic
  eruptions, temperature,
• storms, floods, drought, chemical
  pesticides, and major
• habitat disruption
• C. Organism Interactions Limit Population Size
• 1. Populations also are limited by contact
  with other organisms in a
• community.
• 2. When population numbers are low,
  resources build up and
• become plentiful. Then the population
  will increase in size and
• competition for resources increases
• 3. When populations become crowded,
• individuals may exhibit symptoms of
  stress
• a. aggression

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• II. Human Population
• A. World Population
• 1. Demography is the study of human
• population size, density, and
  distribution,
• movement, and its birth and death
  rates.

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• 2. There are a number of factors that
• determine population growth rate.
• a. births (birthrate) number live
  births per
• 1000 population in a given year
• b. deaths (death rate) number of
  deaths
• per 1000 population in a given
  year
• c. immigration movement of
  individuals
• into a population
• d. emigration movement of individuals
  out
• a population
• 3. Unless the growth rate becomes
  negative,
• the population continues to grow,
  but just
• not as rapid as it did before.
• 4. Doubling time is the time needed for
  a
• population to double in size.

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• 5. Age Structure refers to the number of
  people at
• each different age level.
• 6. The needs for populations differ greatly
• throughout the world.
• 7. There are uneven population growth
  patterns
• throughout the world.