Population Dynamics

Question 1

Define in English each the the variable from the exponential growth equation

Answer 1

Delta N/delta t= (b-d)N

Delta N: change in # individuals
Delta t: change in time
bN: birth rate (times pop abundance)
bd: death rate

Question 2

b-d can be replaced by what

Answer 2

R : difference between the birth rate and death rate per capita

Question 3

If we assume exponential growth, we can predict size of pop using what two things. What is equation

Answer 3

-current abundance and r

Nt = Noe^rt

Question 4

Define Nt=Noe^rt in English

Answer 4

The amount of pop abundance there will be in a future time is equal to current abundance mult by e raised to intrinsic growth rate r and time

Question 5

Pop = 100
R = 0.5
t=4

Answer 5

Nt= 100e^4(0.5)

Question 6

Name two cases where we might expect to see exponential growth in real pop

Answer 6

• with new invasive species

- in early stages of succession

Question 7

Differentiate between density dependent and density independent

Answer 7

• den depend: any var that changes in response to the pop density (competition, water )
• den independ: any var that does not change in response to pop den (temp, weather)

Question 8

What is major difference between logistic growth and exponential growth

Answer 8

Logistic includes term that modulated r and N approaches K
E: density independent
L: density dependent

Question 9

What is the equation for logistic growth, define vars

Answer 9

Delta N/delta t= r(max)N(k-N/k)

Delta N: change pop abundance
Delta t: change in time
N: number of individuals in pop
Rmax: max intrinsic rate of growth of pop
k: carrying cap of environment (how many it can support)

Question 10

Differentiate between rmax (max intrinsic rate of growth) and r (realized rate of growth)

Answer 10

Rmax is constant and never changes while the value of r is a reflection of how close N is to k, r can never exceed rmax

Question 11

Define and describe three types of survivor curves

Answer 11

Type 1: high juvenile survive but lots of death at older age (k)
Type 2: constant mortality across all life stages (squirrels)
Type 3: low juvenile survive but live long after (r)

Question 12

Do we tend to see r strategist species in early or late succession of ecosystem? What about k

Answer 12

• r early because there is not much competition and not many components
• k later because more components and more competition which k strats are adapt for

Question 13

Values of r

Answer 13

R can be neg (pop decreasing)
R is zero (no change, pop is constant)
R is pos (increasing)

Question 14

Are k and r constant in logistic growth equation

Answer 14

No they are both dynamic values that change in time

Question 15

K strategist

Answer 15

Slow growth 
Few offspring 
Later repro 
Large
Repeat repro
Mammals 

Competition (k)
High quality, low quantity

Question 16

R strategists

Answer 16

Rapid growth
Many offspring
Early repro
Small
Single repro
Insects 

Reproduction (r)
Low quality, high quantity