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POPULATION
THE BASICS
GROWTH
LIMITS
REGULATION
POPULATION BASICS
DEFINITION – members of the same species living in the
same place at the same time examples: robins in Westerville,
fish in Hoover Reservoir
PROPERTIES – size (how many), density (number per unit
area), and dispersion (arrangement: 1. even 2. random 3.
clumped)
GROWTH RATE – change in size of a population over time
change in population size = births - deaths
POPULATION GROWTH
REPRODUCTIVE POTENTIAL
WHAT IT IS – the maximum number of offspring that
each member in a population can produce
HOW TO CHANGE IT:
>produce more offspring at a time
>reproduce more often
>reproduce earlier in life – this has the greatest
effect because it shortens the generation time
(the average time taken to reach reproductive
age)
GROWTH
EXPONENTIAL GROWTH
WHAT IT IS: logarithmic growth; rapid growth that increases
by a multiple of the previous generation each time;
represented by a J-shaped curve
NECESSARY CONDITIONS
Plenty of food, space, mates
Little or no competition
Little or no predators
LIMITS
CARRYING CAPACITY
WHAT IT IS: the maximum number of organisms in a
population that the environment can support indefinitely
LIMITING RESOURCE
A resource that is used at the same rate the ecosystem
produces the resource
OR, a natural resource that determines carrying capacity
when it is limited
COMPETITION
DIRECT – members of a population use the same
resources in the same way
INDIRECT – members of a population compete for, or
defend, territory or compete for social dominance
LIMITS
POPULATION GROWTH CURVE WITH LABELS
p. 214
TIME
EXPLANATION OF GROWTH CURVE
POPULATION REGULATION
DENSITY DEPENDENT – the size of the population and the
population density matter; crowded populations are affected
more than low density populations are
DENSITY INDEPENDENT – the size of the population does
not matter, a certain proportion of the population is affected no
matter what the population density is, high or low
REGULATION
EXAMPLES
DENSITY DEPENDENT
Limited resources such as food, water, space,mates
Predation
Disease
Parasitism
DENSITY INDEPENDENT
Severe weather – freeze, drought
Natural disasters – flood, tornado, hurricane
Human disturbance