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GG Gazette
Chapter 5 Population
By Joseph and Amir
What is a
population?!
Have you ever wondered
why and how population
grew? Well, Erik Bailey from
Iowa sent us a letter
regarding this topic. His
letter reads:
Dear Editor,
Although I have been
a reader of your gazette
since the first edition, I have
been curious on the subjects
you address in your articles.
My biggest question on my
mind has been what is
population? Please reply
back soon!
Erik Bailey
Dear Erik,
It’s amazing how we
at the gazette have also been
wondering about how a
population grows and what
factors restricts it!
Editor Joseph S.
2008
Population, as you
know, is the number of a
specific species. There are
three very important
characteristics which
population has. Population
consists of geographic
distribution, density, growth
rate, and age structure.
Geographic distribution is a
term that describes the area
inhabited by a population.
Population density is the
number of individuals per
unit area. This number varies
depending on the different
kinds of species and its
ecosystem.
Population
Growth
The population of each
species can vary from each
year. There is a possibility
the population of a species
can rapidly grow when
factors are met. There are
three major factors that can
affect the size of a
population: the number of
births, deaths and the
number of individuals that
enter or leave the
population. Immigration is
term for the movement of
which travel into a different
location. When individuals
leave their current locations
for another, this is called
emigration.
Exponential
Growth
Above: A graph of exponential
growth at 7% per year over a 50
year span.
Exponential growth
occurs when the individuals
in a population reproduce at
a constant rate. To begin
with, the numbers of
individuals in exponentially
growing populations’
increase slowly reaching its
limit as it grow abundantly
over time. Under several of
ideal conditions with
unlimited resources, a
population will grow
exponentially.
| Capital Gazelles
GG Gazette
Chapter 5 Population
By Joseph and Amir
Logistic Growth
Limiting Factors
Nomad animals are
introduced into a completely
new environment. They
begin to reproduce their
lands, but as the availability
for resources lessen in the
area, the growth of their
population decreases. It is
possible for it to completely
come to an end.
A limiting nutrient is an
example of a more general
ecologist concept: a limiting
factor. In the context of
populations, a limiting factor
is a factor which causes
population to decrease.
There are two different
limiting factors which we will
discuss, density- dependent
and density independent
limiting factors.
This is an example of Logistic
growth, the pattern in which
a population’s growth slows
or stops after following a
period of exponential
growth. The steady number
of the number of individuals
or species when concisely
decreasing is called carrying
capacity. .
Below: In the graph below is an example
of a graph for logistic growth. The line
which stabilizes is called the carrying
capacity.
2008
A limiting factory that
depends on population size
is called a density-dependent
limiting factor. It becomes
limiting only when the
number of organisms per
unit area reaches a certain
level. Competition,
predation, parasitism, and
disease are some densitydependent limiting factors.
When population in an area
overflows, the resources for
each individual decreases,
this leads into fights for the
remaining resources which is
competition.
and sea urchins, sea otters
and killer whales are
examples of predator-prey
interactions that can affect
the population growth of
their species.
Parasites are also a limit in
the growth of a species’
population. Parasites are
similarly to predators in a
variety of ways. For example,
parasites take nourishment
of animal bodies, often
leading to the spread of
disease or death.
A density-independent
limiting factor is different
from dependent as these
factors do not involve the
species of a population but
human nature.
Unusual weather, natural
disasters, seasonal cycles,
and certain human activities
such as forest cutting are all
examples of densityindependent limiting factors.
These listed examples can
easily vanquish a population.
The numbers in population in
nature are often
manipulated by predations.
There are many examples of
predator and prey
relationships. The sea otters
| Capital Gazelles
GG Gazette
Chapter 5 Population
By Joseph and Amir
Human Population
Growth
some countries have high
growth rates while other
countries grow more slowly.
Like many other living
organism populations, the
size of the human population
tends to increase with time.
For many thousands of years,
the human population has
always grown at a steady
rate, but as it increased more
rapidly.
Future Population
Growth
Below: Will we exceed these
extremes?
Scientists have indentified a
variety of other social and
economic factors that can
affect human populations.
This scientific study of
human populations is called
demography. Demography
examines the characteristics
of human populations and
attempts to explain how
those populations will
change over time.
2008
Scientists have predicted
that the worldwide human
population will grow rapidly
in the future to come. They
look at each age structure of
every country, and calculate.
By the year 2025, the world’s
population will exceed 7.8
billion, and will continue to
grow to 9 billion by 2050.
Will our world as we know it
be crowded to every bit and
corner we still remain? Will
there be a massive increase
in population that will be
devastating? We will never
know!
-Your Editors
Joseph and Amir
Birthrates, death rates, and
the age structure of a
population help predict why
| Capital Gazelles