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Community Ecology > Fill in the blanks for lecture 5 > Flashcards

Fill in the blanks for lecture 5 Flashcards

1
Q

_______ and _________ increase population size (_), _______ and ___________ decrease population size.

A

Births and immigration increase population size (N), deaths and emigration decrease population size.

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2
Q

The geometric growth of a population has two assumptions:
1)
2)

A

1) A closed system

2) Population growth is continuous

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3
Q

In the geometric growth of a population equation,
N is ________ ________
r is -
t is ____

A

N- population density
r - per capita population growth rate
t - time

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4
Q

The _________ growth equation is given by dN/dT = rN.

A

exponential

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5
Q

The exponential growth model (single species) assumes what?
1)
2)
3)

A

1) unlimited food and space to grow
2) No predators
3) Closed system (no immigration/emigration)

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6
Q

What is the integrated form of the exponential growth equation?

A 
N(t) = No*e^(rt)
where, 
N(t) = population density at time t
No = initial population density
t = time
r = per capita population growth rate (intrinsic growth rate)
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7
Q

Assume you are rearing a population of insects in the lab. You start with 100 individuals and the intrinsic growth rate is 0.2 insects/week. Assume that growth is continuous.
What would the population of insects be in 6 weeks?

A 
N(t) = No*e^(rt)
N(t) = 100*e^(0.2*6)
N(t) = 332
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8
Q

________ is also called the Verhulst model.

A

Logistic

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9
Q

When comparing the prediction of Verhulst, using the first 5 U.S censuses, he predicted the population growth, and it was found to be?

A

Nearly identical to the actual census data.

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10
Q

Logistic population growth - As a population increases in size (increased density), its growth rate will decline due to:
1)
2)
3)

A

1) Depletion of resource
2) Aggressive interactions among individuals (competition of resources)
3) Increased wastes

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11
Q

________ ________ is a negative feedback between density and per capita growth rate.

A

Density dependence

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12
Q

Logistic population growth assumes?

A

Closed system: no immigration/emigration

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13
Q

Density dependent per capita birth and death rate varies with ________ ______ (______).

A

Population size (density)

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14
Q

The carrying capacity K, is the point at which birth and death rate are _________.

A

equivalent

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15
Q

logistic (or verhulst) single species model - growth in a ________ _________.

A

limited environment

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16
Q

What is the equation for the logistic growth model, and what do each of the variable mean?

A 
dN/dT = rN ((K - N)/K)
where,
dN/dt = change in numbers/change in time
r - intrinsic rate of increase
K - carrying capacity
N - population size
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17
Q

Calculate the % growth for a population with:
K - 4 000
r = 0.1 individuals/year
N - 4 500

A

Thus, since N is larger than K, the % growth must be negative.
dN/dT = rN ((K-N)/K)
dN/dT = 0.1 * 4500 * ((4000-4500)/4000)
dN/dt = -56.25 individuals per year
Then, convert to percentage.
-56.25 individuals/year * 100%/4500 individuals
= -1.25% growth per year

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18
Q

Instead of getting a perfect fit of the logistic growth model in nature, we often get _________ around the carrying capacity.

A

oscillations

19
Q

The logistic growth equation predicts sigmoidal population growth through time. The population size (density) reaches a _______ maximum at K, __ _______ ________.

A

Stable maximum at K, the carrying capacity

20
Q

Visualize how population growth rate (dN/dt) varies as a function of population size. The peark of the dN/dt corresponds to the _______ ____ in the dN/dt vs. time curve.

A

inflexion point

21
Q

The inflexion point in the dN/dt vs. time curve corresponds to / K.

A

1/2

22
Q

dN/dt declines with _________ population size (N).

A

declines

23
Q

Assumptions of the logistic equation are _________.

A

unrealistic

24
Q

The assumptions of the logistic growth model are: (4).

A

CEO SorA

1) Closed
2) no Oscillations/time lags.
3) External environments has no effect on dN/dt,
4) if an individual can reproduce, there is no size or age effect

25
Q

The assumption of a closed system in the logistic growth model lends itself to a _______ ________.

A

linear relationship

26
Q

The assumption of no time lags means that the dN/dt responds _________ to changes in N. Why is this unrealistic?

A

1) immediately

Unrealistic since it takes to to catch up

27
Q

The assumption that if an individual can reproduce, there are no size and age effects is unrealistic since?

A

Unrealistic for real populations. Generally morphology plays a role in differential reproductive success.

28
Q

Field evidence for ______ ______ (typically done along a time scale).

A

density dependence

29
Q

When looking at a meta analysis of the rate of population change per generation (r(G)) (y-axis) vs. log(number of generations monitored) (x-axis), we see that as the number of generations increase we reach a point of _____ ___ ______.

A

Zero net growth

30
Q

Alternative method for testing density dependence. Experimentally alter population sizes. Then measure: (3)

A

birth rate, death rate, population size

31
Q

What factors are important in density dependent population regulation?

A

Top-down regulation: competition, predation

Bottom-up regulation: resources

32
Q

_______ density dependence and Allee effects.

A

positive

33
Q

The allee effect is what?

A

Low densities associated with limited ability to find a mate.

34
Q

Positive density dependence and allee effect.
At what rate do species return after local extinction by an exotic fish?
Recovery of zooplankton is achieved by resting eggs buried in silt.
Studied 4 alpine lakes where non-native trout were removed and _____ __ ______ _____ _____.

A

Looked at recovery over time

35
Q

Daphnia has ________ reproduction.

A

asexual

36
Q

Hesperodiaptomus has ______ reproduction.

A

sexual

37
Q

_______ species may recover from 1 diapausing egg.

A

Asexual

38
Q

An increase in the abundance of 1 species is linked to the decrease in the abundance of another - _________ (_____-___) ________.

A

Compensatory (zero-sum) dynamics

39
Q

Synthesizing 30 years of data from desert rodent community. Shift in vegetation from grasses to woody shrubs and a corresponding change in rodent community. Coexisting granivorous rodents using the ______ _________ _________.

A

same limiting resource

40
Q

What was observed in the shift in rodent communities over 30 years, concerning the grassland and shrubland species.

A

Increase in shrubland species and decrease in grassland species - compensatory dynamics.

41
Q

Despite the species turnover in the rodent study, species _______ has remained constant.

A

richness

42
Q

Temporal trends in granivorous rodents:
Average individual rodent body size _______ significantly over time.
Total rodent abundance _________ significantly over time.
Decline in metabolic rate due to drought, 1985-1995 but no overall change in resource consumption (energy flux). Therefore - ________ ___________.

A

density compensation

43
Q

The idea of compensatory (zero-sum) dynamics is controversial.
Argue that _____ ______ (______ and _______) are more important than ________ _________ in driving fluctuations in species abundances within communities.

A

Argue that abiotic factors (temperature and precipitation) are more important than competitive interactions in driving fluctuations in species abundances within communities.

44
Q

Zero sum or not?
Evidence is mixed.
Likely multiple mechanisms at work. These are? (3)

A

1) Species interactions
2) Resource availability
3) Environmental conditions

Community Ecology (14 decks)

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