1. 1
Population Size
Wendy Lile
SCI275
University of Phoenix
Due March 3, 2012
Sarah Hsu

2. 2
Population Size
The four factors that produce a change in population size are the growth rate, the death
rate, immigration, and emigration. The growth rate is the rate in which people are born and the
death rate is the rate in which people die. If the growth rate is higher than the death rate then the
population increases and if the death rate is higher than the growth rate the population decreases.
Immigration is when peoples from outside the country move in, therefore increasing the
population; emigration is when peoples from inside the country movie out, decreasing the
population.
The two factors that affect the population size in the video are immigration on the
animals and their growth rate. Immigration is a factor because these animals were brought into
our country for fir trading and when the market declined they were just left here and are now
taking over. Their growth rate is a factor because they breed like rabbits and the vegetation in
the area that they are in is diminishing and causing environmental problems and changes.
After the nutria population grows to a certain extent and the land that they are thriving on
disappears they will either move to another location or they will eventually die off because they
never really belonged there in the first place.