Download Population Size and Limiting Factors

Population Size and
Limiting Factors
Population Density
Population density: a measurement of the number of individuals
living in a defined space
Factors that Affect Population Density
IMMIGRATION
BIRTH
•Movement of individuals into a
population
•Increases the size of a population
◦ Increases the size of a population
Factors that Affect Population Density
EMIGRATION
•Movement of individuals out of a
population
• Decreases the population size
DEATHS
Carrying Capacity
• Carrying Capacity: the maximum number of individuals of a
particular species that the environment can normally and
consistently support
• An environment has a specific carrying capacity for each different
species
Carrying Capacity
◦ The actual population size of a species is normally either above or below the
carrying capacity
◦ If the population size gets much larger than carrying capacity some limiting factor will bring the
population size back down
Factors that Limit Population Size
• Limiting factors: environmental factors that limit the size and
growth of a population
Density-Dependent Limiting Factors
• Density Dependent Limiting factors are factors that are
affected by the number of individuals in a given area
•Tend to affect larger populations more
Density-Dependent Limiting Factors
• Competition
oAs a population becomes
more and more dense
individuals compete to
obtain the resources they
need
Density-Dependent Limiting Factors
• Predation
oA large prey population size
means that there is plenty of
food for predators to eat,
thus the population size of
the predator increases, this
will eventually causes the
prey population to decrease
Density-Dependent Limiting Factors
• Parasitism and Disease
o Parasites and disease
spread more quickly
through densely packed
populations because
individuals are constantly
interacting with each other
Density-Independent Limiting Factors
• Density-Independent limiting
factors: are aspects of the
environment that limit the size of
a population regardless of the
size of the population
• Examples:
◦ Unusual weather
◦ Natural Disasters (fires, tornados,
earthquakes)
◦ Human Activities
◦ Destruction of habitat
◦ Pollution
Limiting factors can also be classified as
biotic or abiotic
ABIOTIC FACTORS
◦Water Pollution
◦pH
◦Natural disasters
BIOTIC FACTORS
◦Predation
◦Competition
◦Parasitism and Disease
Symbiosis Review
Ostriches and gazelles feed next to each other.
The both watch for predators. Because the
visual abilities of the two species are different,
they can each identify threats that they other
animal may not be able to see.
Tapeworms reside inside the human intestine
and take nutrients from the humans.
E coli is a bacteria that in the gut of humans.
The human provides the ideal habitat for E coli
and the E coli provides the extra vitamin K that
we use.
Epiphytes are a class of plants that grow in the
crooks of tree branches. The simply use the
branches as a way to be higher and closer to the
sunlight they need for photosynthesis.