2.2 Flashcards
How is population growth determined by births, deaths, immigration, and emigration?
Population growth increases by births and immigration and decreases by deaths and emigration.
If there are more births and immigration than deaths and emigration, then the growth is positive
If there are less births and immigration than deaths and emigration, then the growth is negative
If births and immigration are equal to deaths and emigrations, then the growth rate is neutral.
What is the difference between a logistical and exponential graph in terms of drawing?
An exponential graph grows exponentially (hence the name) and is drawn with the line growing higher and higher.
A logistical graph grows and then maxes out, making an S curve.
At what points are the population growths the highest in exponential and logistical graphs?
For exponential, it is at the line’s highest point
For logistical, it is at half of the maximum growth rate (K)
What do the variables mean?
N
t
N_0
r
K
dN/dt
N = Population size
t = Time (usually in years)
N_0 = Original population size
r = Maximum per capita rate of growth
K = Carrying capacity (used for logistical graphs)
dN/dt = Growth rate
What is a density dependent factor?
List some examples.
Density dependent factors are factors in which their effect is based on the density of the population
Some examples include: disease, social behavior intraspecific competition (competition between the same species), and interspecific competition (competition between two different species).
What is a density independent factor?
List some examples.
Density independent factors are factors in which their effect is completely unrelated to the density of the population
Most examples are of abiotic factors like natural disasters, temperature, and more.
How does an exponential model change when r is changed?
The larger r gets, the steeper the curve becomes, and vice versa.
How does a logistical model change when r is changed? When K is changed?
As r gets larger, the curve gets smaller, and vice versa. As K becomes larger, the curve gets larger, and vice versa.
