Transcript Population Size

Population Size
Features of Populations 1
Population size: the total number
of organisms in the population.
Population density: the number of
organisms per unit area.
Population distribution: the
location of individuals within a
specific area.
What’s happening to the rabbits?
Why? What will happen?
What’s happening to the rabbits?
Why?
Population Dynamics
Natality (birth rate): the number
of individuals born per unit time.
Mortality (death rate): the number
of individuals dying per unit time.
Migration: the number moving into
or out of the population.
Population size is influenced by births…
…and deaths
Migration
Migration is the
movement of
organisms into
(immigration) and
out of (emigration) a
population.
Wildebeest
Populations lose individuals
through deaths and emigration.
Populations gain individuals
through births and immigration.
Canada geese
Migrating species may group together to
form large mobile populations
Population Density
The number of
individuals per unit
area (for terrestrial
organisms) or volume
(for aquatic organisms)
is termed the
population density.
At low population densities, individuals
are spaced well apart. Examples:
territorial, solitary mammalian species
such as tigers and plant species in
marginal environments.
Low density populations
At high population densities,
individuals are crowded together.
Examples: colonial animals, such as
rabbits, corals, and termites.
High density populations
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Classify each of these factors as
density-dependent or densityindependent on population size
Rainfall Competition Predation Human destruction Parasites Temperature Disease Food availability -
Assignment:
• Create a concept map with interconnections,
and action words about Population Size.