How Populations Grow - Brookwood High School

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Transcript How Populations Grow - Brookwood High School

How
Populations
Grow
A. Population size: total # of
organisms.
B. Population growth:
increase in size of
population with time.
C. Population density: # of
individuals per unit area.
D. Limiting factors:
conditions that keep
organisms from reaching
their maximum population
numbers.
• what are some
examples??
Examples of limiting factors:
Competition
Predation
Parasitism
Disease
Climate
Humans
E. Population Growth Curve
1. J-Shaped curve: under
ideal conditions;
exponential growth
#
Time
2. S-Shaped curves:
population gets to a stable
point, limiting factors have
influenced growth; Logistic
growth
#
Time
F. Carrying capacity: maximum
population level that can be
supported with the resources
available.
1. Not only during that
organism’s lifetime, but also
future populations.
2. What is the earth’s
carrying capacity?
G. Density-independent limiting
factors: something that affects all
populations, regardless of size.
1. Ex: storms or hurricanes,
climate
H. Density-dependent factors:
Effect increases with crowding
and can bring a pop under
control.
1. Ex.- Disease, predators,
parasites
I. Human population growth:
-controlled by war, famine, and
disease
1. Demography: study of human
populations
2. Demographic transition: change
from high birth and death
rates to low birth and
death rates.
J. Competition
1. Intraspecific – between the same
species
2. Interspecific – between different
species