EE29

Question 1

What are true predators?

Answer 1

consume many whole prey in life

Question 2

what are grazers?

Answer 2

consumer only part of their pray but may attack many

Question 3

what are parasitoidss?

Answer 3

free living adult
insect lays eggs in host. = 10% of all species.
many are wasps

Question 4

what are parasites?

Answer 4

consume parts of hosts

typically only one host per life time

Question 5

What is the functional response?

Answer 5

if each predator ate its full prey each day irrespective of prey density.
intake rate of consumer as a function of food density.
On a graph of prey available by prey eaten this would be a vertical line

Question 6

What happens to Functional response if there are no prey? - cant be eaten

Answer 6

demand exceeds supply

FR must decline.

Question 7

What is type 1 functional response?

Answer 7

assumes a linear increase in intake rate with food density

• more prey present - more predatoes will eat
• increasing FR through origin.
• assumes infinite appetite.

Question 8

What is type 2 functional response?

Answer 8

curve must saturate at some point.

• decelerating intake rate
• assumes consumer is limited by its capacity to process food

Question 9

What does the % of prey eaten as opposed to number of prey look like on a graph?

Answer 9

the inverse of a graph of number of prey

Question 10

What does stability require?

Answer 10

density dependence

- higher proportion of prey eaten at a higher density than a low.

Question 11

If predation is stabilizing what is this in spite of?

Answer 11

functional response

not because of it

Question 12

How may the functional response be stablizing?

Answer 12

because of switching between prey species or other behaviours that reduce rate of predation
- this is type 3

Question 13

What is the equation for the nicholson bailey model?

Answer 13

H+1= RHte^-apt
Pt+1 =cHt(1-E^-apt)
Ht= density of host
Pt densiry of parasitoid
e^-apt = probability that with random encounters host escapes
1-e^-apt = proportionally constant = search efficiency
c = conversion rate of hosts into parasitoids
R= no. of unparasitoided host offspring surviving to the next year
simplified
Ht+1 = RHt x probability of escape
Pt+1 = cHt X probability of parasitzing.

Question 14

What is the nicholson bailey model?

Answer 14

The model uses difference equations to describe the population growth of host-parasite populations. The model assumes that parasites search for hosts at random, and that both parasites and hosts are assumed to be distributed in a non-contiguous (“clumped”) fashion in the environment.

Question 15

What does spatial heterogeneity refer to?

Answer 15

uneven distribution of various concentrations of each species within an area

Question 16

Why is the nicholson bailey model inherantly unstable?

Answer 16

because tiny deviations from equilibrium means population collapse
H0 = R/R-1 log(R)/ac
P0=log(R)/a

Question 17

In continuous time models what kind of aggregation is stabilizing?

Answer 17

only density dependent aggregation as it always lowers host density

Question 18

When is aggregation stabilizing?

Answer 18

in nicholson bailey model
cant stabilize interactions via enemy free refuge
and because of increased inefficiencies in foraging as parasitoid density increases.