Transcript Population Dynamics

Population
Dynamics
Life Science
Populations Change!
 Population Dynamics is the study of
why populations change and what
causes them to change
 All living things need resources such as water,
energy and living space.
 Carrying Capacity- maximum number of
individuals an ecosystem can support
Three stages of
population change
 Growth- population increases in size.
Birth > Death.
 Stability- the population does not
increase the same
 Decline- the population decreases in
size Death > Birth
Patterns of Growth
 Rapid growth- very sharp increase in the
numbers of individuals in a population
 Gradual growth-
Darwin and his
observations
 All populations are able to grow rapidly
 Populations tend to remain constant in
size
 There are limits to the natural resources
 Within a given population there is genetic
variation
Characteristics that
define a population
 Population size- the number of
individuals in a population at a given
time
 This can be a result of a climate change, time of
year, and availability of resources
 Population density- the measure of the
number of individuals living in a certain
space
 Low density
 High Density
Population Spacing
Clumped-gather around resources in groups
Uniform-evenly space themselves compete for
resources
Random-no regard to individuals, or resources
Age Structure
 Age determines the amount on how
much a population can grow
 Post reproductive- organisms that can
no longer reproduce
 Reproductive- organisms capable of
reproduction
 Pre-reproductive- not yet able to
reproduce
How can scientists predict
population change?
Populations Respond
to Pressures
8-2
Population Responding to
Pressures
 Population growth is limited
 This is a result of many factors
 Birth- numbers of births in a population
 Death- numbers of deaths in a population
 Immigration- movement of individuals out
of a given area
 Emigration- movement of individuals out
of a population
Population Change
= (birth + immigration)-(death + emigration)
Limiting Factors
 Prevents the continuing growth of a
population
 Density – Dependent Factors
 Density – Independent Factors
Density Dependent Factor
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Competition
Disease
Parasitism
Predation
Density Independent
Factors
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Drought
Hurricanes
Tornados
Fires
Floods
Survival Strategies
 Opportunists- species that reproduce
rapidly and have a short life span
 Competitors- species with adaptations
that allow them to remain near their
carrying capacity for long periods of
time