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HELENP EE POPULATION ECOLOGY > EE Lecture 29: Predation 1 > Flashcards

EE Lecture 29: Predation 1 Flashcards

1
Q

what are the main types of predators

A

true predators - consume many prey
grazers - consume only part of their prey, but attack many
parasitoids-free living adult insects, lay eggs inside of host
parasites - consume parts of hosts, but typically one host per life time

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2
Q

what is a true predator

A

low intimacy, high lethality - org consume WHOLE prey and many prey in their life

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3
Q

what are grazers

A

org consume only part of their prey, but attack many

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4
Q

what are parasitoids

A

free living adult insects-lay eggs inside hosts

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5
Q

what are parasites

A

predators that consume parts of host,but typically one host per lifetime

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6
Q

how much % are parasitoids of all species

A

`10% of all species are parasitoids

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7
Q

when does functional response decline

A

when demand of prey exceeds supply

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8
Q

whats on the axes of a functional response graph

A

x - prey available

y - prey eaten per predator

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9
Q

what is a functional response

A

relationship between prey eaten and prey available

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10
Q

give an example of a predator prey cycle

A

snowshoe hare cycle - popns increased and decreased regularly
their predators were lynxs
abundancies every 10 yrs
food can be limiting at peak hare densities,
lynx and coyotes kill more hares per day during the peak and decline phases of the hare cycle than during the increase phase
after predator numbers plummet
physical condns of hares worsens as hares decrease in numbers

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11
Q

what are main “anomalies” of hare-lynx popn cycles

A
  1. why hare BRs drop during the decline phase of the cycle
  2. why hare numbers sometimes rebound slowly after predator numbers plummet
  3. why the physical condns of hares decrease, when hare pops decrease
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12
Q

what is masting

A

when some plants avoid herbivory by producing seeds some years and not othera

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13
Q

how many functional responses are there

A

3
I - assumes a linear increase in intake rate with food density - suggests infinite appetite of predators
II - when type I satiates - saturating curve dependent on apetite
III - like II but low density line is more linear to account for the learning time&/prey switching

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14
Q

what is the flaw of the type I functional response

for which predators does this not count

A

suggests infinite appetite of predators

ok for passive predators - eg. spiders with webs

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15
Q

what is the type I functional response

A

infinite appetite of predators, constant positive correlation straight line through origin

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16
Q

what is type II FR

A

type I but it satiates - characterised by decelerating intake rate follows from the asusmption that the consumer is limited by its capacity to process food

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17
Q

why does the graph of type II FR satiate

A

because its dependent on predators appetite - counts for the fact that a predator is limited by its capacity to process food and search food

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18
Q

what is type III FR

A

similar to type II in that high levels of prey density saturation occurs, but becomes SIGMOIDAL - like the logistic eqtn
@ low prey density levels, the graphical relnship of no. of prey consumed and the density of the prey pop is moer than linearly inc function - caused by LEARNING TIME &/ prey switching

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19
Q

why is type III FR more linear

A

accounts for learning time &/ prey switching

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20
Q

which FR type is a linear increase

A

type I

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21
Q

which FR type is a linear increase which then levels off

A

type II

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22
Q

which FR type is a sigmoidal shape

A

type III

23
Q

which FR type assumes infinite predator appectite

A

FR type I

24
Q

which FR type accounts for learning time&/ prey switching

A

Fr Type III

25
Q

which FR type accounts for saturation predator appetite

A

type II

26
Q

what is a functional type 2 response aka

A

inverse density dependence

27
Q

if you think of a FR type II as %prey as opposed to number, what graph do you get

A

inverse density dependence

28
Q

what does stability require

A

density dependence - a higher proportion of prey eaten at high densities rather than low

29
Q

what ways of stabilising a pop are there

A

density dependence
aggregation
numerical response

30
Q

what is a numerical response

A

a change in predator numbers in response to a change in prey numbers

31
Q

compare numerical and functional response

A

functional response shows relnship between prey no. and prey eaten whereas numerical is a change in predator numbers in response to a change in prey numbers

32
Q

give a common mechanism of numerical response

A

spatial aggragation

33
Q

what is spatial aggregation

A

predators move into regions with higher than average prey numbers
predators emigrate from patches once prey numbers become depleted

34
Q

how do numerical responses act in the long term

A

act through changes in the predators birth and death rate
more prey = higher predator birth rate
more prey = low pred DR

35
Q

why will stability come from the predators numerical response and not the functional response

A

because the FR is inversely density dependent and hence destabilizing

36
Q

which is more destabilizing, FR or NR

A

FR is more destablizing because it is inversely density dependent and hence destabilizing

37
Q

which FR type is stabilizing

A

type 3

38
Q

when is a FR stabilzing

A

when switching between rpey species/behaviours that reduce the rate of predation become scarce (eg.loss of search image)
this is in type 3

39
Q

which FR is Hollings?

A

type 3

40
Q

what models for popn dynamics are determined by NRs

A

nicholson bailey

lotka volterra

41
Q

what are the nicholson bailey models

A

Ht+1 = RHt * e^-aPt

Pt+1 = cHt (1 - e ^ -aPt)

42
Q

in NB models -nicholson bailey models - what does Ht and Pt represent

A

density of host and parasitoid at year t

43
Q

in NB model, what is R

A

no. unparasitized host offspring surviving to next year

44
Q

what is e^-aPt representing in the NB model

A

represent the probability that host escapes random encounters

45
Q

what is (1- e^-aPt) representing in the NB model

A

the probabilty of the parasitoid parasitizing (being parasitized)

46
Q

what does a represent in NB model

A

a proportionality constant - search efficiency

47
Q

what does c represent in NB model

A

conversion rate of hosts into parasitoids

48
Q

why is NB model so unstable

A

any deviation @ all results in unstable dynamics as any data out of sync will crash the popn- but it does coincide with real data

49
Q

WHEN is it a good idea to use the NB model

A

when testing biological control for parasitoids because you want the popn of parasitoids to crash

50
Q

what is eqbm for NB model

A

H0 = R / (R - 1) * log(R)/ac

Po - log (R) / a

51
Q

H0 = R / (R - 1) * log(R)/ac
Po - log (R) / a
what do these show

A

show the inherent instability in NB, eqbm given by these eqts

52
Q

what is the drawback of aggregation

A

it is stbailizing but may increase host popn size

aggregation stabilizes by causing partial refugia

53
Q

what does direct inverse dependence mean (in terms of parasitoid/predators)

A

direct inverse dependence means that at high parasitoid densities, predators interact and interfere reducing effective attack rate

HELENP EE POPULATION ECOLOGY (8 decks)

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