Chapter 4 Population Biology
4.1 Population Dynamics
A. Principles of ____________ _____________ – an increase in the size of a population over time.
1. How fast do populations grow? – Scientists __________ organisms within a population
to show growth patterns. By evaluating growth patterns, __________ __________ can be determined.
a). __________ __________ – a population
b). __________ __________ - as a population gets
with constant growth. (“straight line” graph)
larger it also grows faster. (“J” shaped curve)
# of
# of
organisms
organisms
Time
Time
2. Limits of the environment – Populations do ____ seem to _____ indefinitely. Every
population has limiting factors that _________ growth. These factors may be _________or __________.
3. Patterns of population growth – ecologists use graphs to __________ growth patterns
c). ________________ The number of
d). __________ ________ – as a population reaches the carrying
species an environment can support.
capacity, it levels off with slight fluctuations. (“S” Shaped curve)
# of
# of
organisms
organisms
Time
Time
4. Environmental limits to population growth
c). __________ -__________
__________ - disease, parasites, or food supplies that have
# of
an increasing affect as populations increase.
organisms
Time
(disease)
d). __________ -__________
__________ - disruptions that affect all
populations regardless of density (temp.
# of
storms, floods, drought…)
organisms
Time
(meteor )
B. Organism Interactions Limit Population Size – abiotic factors are not the only limiting factors.
1. Predation affects population size -________
are necessary to keep certain pop’s __________. Usually,
the __________ members of a population are either the old
or the young. Predation ensures __________ __________
for resources within a population. Predator and prey
populations fluctuate __________.
2. The effects of competition – organisms
__________ for resources, those most “fit” survive and ___________ ___
3. The effects of crowding and stress – the _____________ can NOT support all members
of a population, more members are _______________ then can_________________
4. Limiting factors influence Natural selection’s 4 points: 1. in a population, more
organisms are produced than can survive 2. In a population there is _______________ 3. Some variations
are _______________4. Those with favorable variations can _______________ and _______________.
4.2 Human Population Growth- a good way to predict
human population growth is by looking at the ______
population _______________.
A. Demographic Trends
1. _______________ - the study of
human population growth characteristics
2. Effects of birthrates and death rates –
a population is _______________ if there is a
higher birthrate than death rate and is _______________ if the death rate is greater than the birthrate. If the
birth and death rates are equal than the growth is _______________.
3. Does age affect population growth?
a). _____ __________ – proportions
of a population that are at different age levels
4. Mobility has an effect on
population size – if a population is geographically
isolated, it’s gene _________can become slightly
different then other populations of that species
b). __________ Movement into a
population
c). _______________ - Movement from a population