Lecture 4 - Density dependence, intraspecific competition

Question 1

logistic growth happens ..

Answer 1

after exponential 
l            ----------- (K)
l           /  (-ve feedback)
l          /  (exponential)
l  -----/
\_\_\_\_\_\_\_\_\_\_\_
y= pop size x= time

Question 2

logistic growth equation

Answer 2

dN/dt = rN (K-N/K)

Question 3

equilibrium needs

Answer 3

persistence
stability
coexistence

density dependence = linear

Question 4

human population growth

Answer 4

more extreme than exponential, we manipulate environment

Question 5

per capita exponential rate

Answer 5

(dN/dt) = rN = r
______ ____
N N

divide growth equation by pop size
horizontal line
no density dependence

Question 6

per capita logistic rate

Answer 6

(dN/dt) = rN - (rN^2/K)
______ ____ _______ = r - r / K * N
N N N

negative slope line
density dependence

Question 7

assumptions of logistic model

Answer 7

• density dependence linear
• pop approaches K smoothly - but may overshoot, time delay
• K is constant - but there are yearly variations

doesn’t apply to all populations, model if framework to compare

Question 8

r and K selected species

Answer 8

selection acts on indvs not on r and K (population level parameters)

Question 9

high density

Answer 9

K selected
high competition, low resources
large, few offspring, long lived
delayed reproduction

Question 10

low density

Answer 10

r selected
many, small offspring, short lived
early reproduction