ch4,sec1
common patterns of dispersion :
Population density
Dispersion
the number of organisms per unit area
is the pattern of spacing of a population
within an area
clumped
random
uniform
EX:-. Black bear
Ex:-. American bison
Ex:-. White-tailed dear
limits spatial distribution
their is no species that lives in all biosphere. this happens because the species cant survive the new conditions
population limiting factors
limiting factors keep a population population from growing indefinitely
Ex: food supply
density-independent factor
A density-dependent factor is any factor in the environment
that depends on population density. these are biotic factors
is any factor in the environment that does not depend on
population density. the are abiotic factors
Ex: drought, floods, and hurricanes
Competition
Parasites
Disease
Predators
occur when a
population has increased and population density is high
increasing competition among indivisibles for resources because food and space are limited
parasites spread super fast just like diseases
when their are plenty of prey for the predator to consume the prey population will decrease then with fewer prey to consume the predator population decreases
population growth rate is a measure of how fast
a given population grows
death rate (mortality): is the
number of individuals that die in a given time period
birth rate (natality):s the number of individuals that are
born in a given time period
Emigration: is the
number of individuals moving away from a population.
Immigration: is the number of
individuals moving into a population
logistic growth
Exponential Growth
show how growth will be with out limiting factors gives the graph a (J-shape)
this graph shows the rapidly increasing population
will strain available resources (S-shape)
carrying capacity: is the maximum number of individuals in a species that an environment can support for the long term
reproductive strategies
r-strategists are (small organisms)
short life span
produce as many offspring as possible and do not nurture them
controlled by density-independent factors
and does not stay near the carrying capacity.
k-strategists (are large
organisms)
They usually have long lives
few offspring and nurture them
controlled by density-dependent factors
and stays near the carrying capacity