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EES 152 Bob Booth > 8.14. (10/16) Population Dynamics & Growth > Flashcards

8.14. (10/16) Population Dynamics & Growth Flashcards

1
Q

What is birth rate?

A
  • the number of young born per female (individual) per unit of time
  • refers to the addition of new individuals to a population
  • number of individuals being born
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2
Q

What do we need to know to track birth rates?

A
  • number of individuals (females) per age class
  • average number of births per individual
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3
Q

what is a fecundity schedule?

A

summary of the number of individuals (females) being born at different age classes through time

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4
Q

What does a life table do?

A

how many individuals are surviving to each age class

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5
Q

What can we find out with fecundity schedules and life tables?

A

estimates like how fast this population is growing

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6
Q

What is the net reproductive rate?

A

avg number of offspring produced per individual in the population
*R0

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7
Q

What is the geometric rate of increase?

A

the estimated rate at which a population with pulsed reproduction is increasing
*λ

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8
Q

What is pulsed reproduction?

A
  • no overlapping generations
  • individuals are born, reproduce, and die
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9
Q

What is generation time?

A

average time it takes for an individual to move from one birth to the next
*T

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10
Q

what is per capita rate of increase?

A
  • birth rate minus death rate
  • the best way to express how quickly a population is growing or declining
    *important for rate of growth
    *r
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11
Q

What information is in a life table?

A

age, number of surving to day x, proportion surviving to day x (lx survivorship)

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12
Q

What information is in a fecundity table?

A

average number of seeds per individual during time interval (mx fecundity), lxmx

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13
Q

How do we calculate net reproductive rate?

A

the sum of the proportion of individuals surviving to each age class multiplied by average number of seeds produced
*R0=Σlxmx

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14
Q

What does the calculation for net reproductive rate mean?

A

each individual leaves an average of __ offspring

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15
Q

How do we calculate the total number of seeds produced by the population cohort?

A
  • population multiplied by the average number of seeds produced per individual
  • seeds produced by the end of a year
  • R0*N1
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16
Q

How do we calculate geometric rate of increase?

A
  • comparing the population size at two points in time
  • ratio of population at some future time divided by size of population at some earlier time
  • slope
  • Nt+1 future time
  • Nt earlier time
    *λ=Nt+1/ Nt
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17
Q

When might λ=R0?

A

the geometric rate of increase is equal to the net reproductive rate when organisms have pulsed reproduction (like annual plants)

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18
Q

What do we need to calculate net reproductive rate (R0)?

A
  • fraction of females reproducing during each time interval
  • average clutch size
  • number of reproductive events per time interval
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19
Q

What does clutch size mean?

A

number of offspring produced by an average female per reproductive event

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20
Q

What is the trend for a stable population?

A

R0=1
each female is producing on average one other female

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21
Q

What is the trend for a declining population?

A

R0<1

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22
Q

What is the trend for an increasing population?

A

R0>1

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23
Q

How do we calculate generation time?

A

the sum of the years times survivorship times fecundity divided by the net reproductive rate
* τ=(Σxlxmx)/R0

24
Q

How do we calculate per capita rate of increase?

A

r= ln(R0)/T

25
Q

What does natural log do?

A

gives us the amount of time needed to reach a certain level of growth

26
Q

What does r=0 mean?

A

stable population

27
Q

What does r<0 mean?

A

declining population

28
Q

What does r>0 mean?

A

growing population

29
Q

When would we have positive growth?

A

birth or immigration

30
Q

When would we have negative growth?

A

death or emigration

31
Q

When do we have a stable population?

A

births + immigration = deaths + emigration

32
Q

What is a discontinuous model?

A

geometric population growth model for populations with non-overlapping generations and no limits to growth
*bamboo, cicadas, salmon, annual plants, insects, spiders

33
Q

How do we calculate the size of a population that grows geometrically for any given time interval?

A

Nt= N0λ^t
- Nt: number in population at some time t
- N0: number in population at some initial time
- λ: average number of offspring left by an individual during a time interval (geometric rate of increase)
t: number of time intervals

34
Q

What is exponential population growth?

A
  • for populations with overlapping generations
  • no limits to growth
  • continuous model
  • smooth curve
35
Q

What is the exponential model?

A

dN/dt= rN
- dN/dt: change in numbers with changes in time
r: per capita rate of increase
N: population size

36
Q

In the exponential growth model what happens as N increases?

A

the rate of population change increases

37
Q

How do we calculate the size at any given time (t) for a population growing at an exponential rate

A

Nt=N0e^rt
Nt: number of individuals at time t
N0: initial number of individuals
e: base of the natural logarithms (constant 2.72)
rt: per capita rate of increase*number of time intervals

38
Q

What does e^x do?

A

gives you the amount of continuous growth that you would have after a certain amount of time

39
Q

What did Malthus do?

A

described the logistic growth model

40
Q

What is carrying capacity?

A

the number of individuals in our population that an environment at some time can support
*K

41
Q

What is an s-shaped curve?

A

growth appears exponential at first, but the rate of increase slows and levels off after some time

42
Q

What factors cause populations to slow their growth rates and eventually stop at their carrying capacity?

A
  • yeast –> alcohol waste
  • barnacles –> available space
  • paramecium –> food resources
    *determined by a complex interplay of factors
43
Q

What is the equation for logistic growth?

A

dN/dt= rmaxN(1-N/K)

44
Q

What does (1-N/K) do in the logistic growth equation?

A

as the population approaches the carrying capacity the growth slows down
* as soon as population equals carrying capacity it’ll go to one giving you a zero value that means there is no more growth

45
Q

What is maximum per capita rate of increase?

A
  • rmax
  • occurs at very low population sizes
  • birth rate, death rate, and age structure are constant
  • under ideal conditions
  • intrinsic rate of increase
  • if everything was perfect for a species how high would their r value be?
46
Q

What is another way to write the logistic model in terms of r and rmax?

A

r= rmax- rmax(N/K)
r: realized per capita rate of increase
*r is being modified by how close the population size is to K

47
Q

What is happening to r and rmax when a population size is small?

A

the realized is equal to the maximum

48
Q

What is happening to the r and rmax when population size increases?

A

realized decreases until the population size equals the carrying capacity
* r=0 (no growth)

49
Q

what is the relationship between realized and population size in a logistic model?

A

r decreases as N increases

50
Q

What happens to r if N<K?

A

r is positive and the population grows

51
Q

What happens to r if N=K?

A

r=0 and population growth stops

52
Q

What happens to r if N>K?

A

r is negative and the population declines

53
Q

How are organism size and rmax correlated?

A
  • inversely
  • the intrinsic rate of increase declines with increasing size
54
Q

What are the two factors that limit population growth?

A

density dependent and independent factors

55
Q

What are density-dependent factors?

A
  • product of increasing number of individuals
  • food
  • predation
  • available space
  • nest sites
  • parasitism
  • disease*
  • biotic factors
    *could be density-independent
56
Q

What are density-independent factors?

A
  • affects on growth rate that have nothing to do with the number of individuals on the landscape
  • drought/flood
  • storms
  • fire
  • abiotic factors

EES 152 Bob Booth (16 decks)

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