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Ecology > Ch. 10 Population Growth & Regulation > Flashcards

Ch. 10 Population Growth & Regulation Flashcards

1
Q

Life tables contain..

A

Information about births and deaths that is essential to predict trends or future population size

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2
Q

___ show how survival and reproductive rates vary with age, size, or life cycle stage.

A

Life tables

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3
Q

Age-specific survival rate (Sx)

A

Chance that an individual of age x will survive to age x+1

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4
Q

Survivorship (Ix)

A

Proportion of individuals that survive from birth to age x

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5
Q

Fecundity (Fx)

A

Average number of offspring produced by a female while she is of age x

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6
Q

Cohort

A

Individuals born at the same time

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7
Q
  • Cohort life table
A
  • follows fate of a group of individuals all born at the same time
  • mostly used for non-mobile organisms
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8
Q
  • Static life table
A
  • survival and reproduction of individuals of different ages during a single time period are recorded
  • requires estimating the age of individuals
  • easier for mobile or long-lived organisms
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9
Q
  • Survivorship curves
A

Plot of number of individuals from a hypothetical cohort that will survive to reach certain ages

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10
Q
  • Survivorship curve

Type I

A

Most individuals survive to old age

Ex: most Dall mountain sheep survive to old age
Ex: U.S. Females

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11
Q
  • Survivorship curve

Type II

A

Chance of surviving remains constant throughout life

Ex: song thrushes have about the same chance of survival at any age

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12
Q
  • Survivorship curve

Type III

A

Individuals die at high rates when young, those that reach adulthood survive well

Ex: oysters
Ex: species that produce large numbers of offspring
Ex: out of a million Cleome seeds, only 39 survive to produce 1-year-old plants

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13
Q

Survivorship curves can vary…

A
  • among populations of a species
  • between males and females
  • among cohorts that experience different environmental conditions
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14
Q
  • Age structure
A
  • proportion of population in each age class

- influences whether a population will increase or decrease in size, and how fast the population will grow

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15
Q
  • Rapid growth
A

Younger age groups are larger

Ex: Guatemala, Nigeria, Saudi Arabia

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16
Q
  • Zero growth
A

Relatively similar-sized age groups

Ex: Spain, Austria, Greece

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17
Q
  • Negative growth
A

Older age groups are larger

Ex: Germany, Bulgaria, Italy

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18
Q

Which population can sustain social security longer?

A

Rapid growth

- more younger people to pay taxes for older people’s social security

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19
Q

To predict population size for following year, two things must be calculated:

A
  • survival

- fecundity

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20
Q

Growth rate (lambda)

A

Ratio of population size in year t+1 to population size in year t

Lambda > 1, population grows
Lambda < 1, population declines
Lambda = 1, population is stable

21
Q

Stable age distribution

A

If age structure does not change from one year to the next

22
Q

Continuous growth

A

When individuals leave an average of more than one offspring over substantial periods of time

23
Q

Geometric growth

A
  • population reproduces in synchrony at regular time intervals, and growth rate remains the same
  • population increases by a constant proportion
  • visualize geometric growth as a set of discrete points
24
Q

Translation

A

The population size at the next period

Predicted to be simply the current population size * the geometric growth rate

25
Q

Exponential growth

A
  • reproduces continuously -> generations overlap

- continuous, a line

26
Q

Exponential growth

r =

A

Exponential population growth rate or intrinsic rate of increase

27
Q

Exponential growth

Closed population

A

b-d (instantaneous birth rate - instantaneous death rate)

28
Q

Exponential growth

Open population

A

(b + immigration) - (b + emigration)

29
Q

Doubling time

A

Number of years it will take the population to double in size

30
Q

Net reproductive rate

A

Mean number of offspring produced by an “average” individual during its lifetime

31
Q

Growth rate may change independently of ___ or as a function of ___.

A

Density

32
Q
  • Density-independent factors
A
  • factors such as temperature and precipitation, and catastrophes such as floods or hurricanes
  • such factors affect density, but the effects are not related to density
  • birth & death rates are not affected

Ex: the insect population size fluctuations are correlated with temperature and rainfall

33
Q
  • Density-dependent factors
A
  • cause birth & death rates, and dispersal rates to change as population density changes

Ex: when sending a bunch of horses from US to Germany, the horse population density increased, one horse could have gotten infected with a disease, they disease would spread quickly, and all the horses would have mostly been dead by the time they got to Germany.
Ex: in song sparrows, number of eggs laid per female decreased with density, as did number of young that survived

34
Q

Density-dependent factors

As densities increase…

A
  • birth rates often decrease
  • death rates increase
  • dispersal from the population increases
  • all tend to decrease population size
35
Q

Population regulation

A

Occurs when density-dependent factors cause population to

  • increase when density is low
  • decrease when density is high
  • can maintain population at relatively stable size in stable environment

Density-independent factors can have large effects on population size as well, but they do not regulate population size

36
Q

Logistic growth

A
  • Population increases rapidly at first
  • then stabilizes at carrying capacity (K)
  • growth rate decreases as population size nears carrying capacity
37
Q

Carrying capacity (K)

A

Maximum population size that can theoretically be supported indefinitely by environment

38
Q

At carrying capacity, growth rate is ___.

A

Zero

39
Q

How does logistic differ from exponential and geometric growth?

A
  • In exponential growth, r is assumed to be constant
  • in logistic growth, we assume that r declines as density increases
  • initially, logistic growth is similar to exponential growth
  • eventually, a population that grows logistically levels off at the carrying capacity
40
Q

N

A

Population density

41
Q

r

A

Per capita growth rate

42
Q

K

A

Carrying capacity

43
Q

1 - N/K

A

Discounts growth as N approaches K

44
Q

Logistic growth

When N is small,
As density increases,
As density approaches K,

A
  • A population with logistic growth increases at a rate close to r
  • growth rate decreases
  • growth approaches zero
45
Q
  • Logistic growth curve
A
  • slope of curve at any point = rate of population growth at that time
  • inclination point has max growth rate -> max sustainable yield
  • management goal to maintain population close to K/2
46
Q
  • Ecological footprint
A
  • total area required to support a human population

- humans are different because of our technologies that can alter K (agriculture, medicine, energy utilization)

47
Q

Ecological footprint approach

A

Carrying capacity depends on amount of resources used by each person

48
Q

___ is the environmental impact of a population.

A

Ecological footprint

Ecology (12 decks)

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