Deck 9: Population Growth

Question 1

Life ________ refers to the average number of years that an individual is expected to live from the time of his or her birth.

Answer 1

expectancy

Question 2

________ stochasticity is the random variation in birth and death rates that occurs in populations from year to year as a result of natural disasters and other annual variations in the environment.

Answer 2

Environmental

Question 3

Population ________ refers to the rate at which the number of individuals in a population increases or decreases with time.

Answer 3

growth

Question 4

A(n)________ life table is constructed by sampling the population to obtain a distribution of age classes during a single time period.

Question 5

There is no change in population size when the instantaneous per capita rate of growth (r)is equal to ________.

Question 6

The ________ birthrate is expressed as the births per 1000 individuals per unit of time.

Question 7

A population eventually becomes ________ when its population growth (r)remains negative without reversing.

Question 8

A population that is increasing in size has an intrinsic rate of population growth (r)that is

A)< 0.
B)= 0.
C)> 0.
D)> 1.

Question 9

________ is the study of populations.

Question 10

A(n)________ curve plots the probability at birth of surviving to any given age (lx)against time or age class (x).

Question 11

The pattern shown in figure 9.6 best resembles

A)a survivorship curve.
B)exponential growth.
C)R0= 0.
D)r < 0.

Question 12

Movement in and out of a population occurs in a(n)________ population.

Question 13

________ stochasticity is the random variation in birth and death rates that occurs in populations from year to year.

Question 14

When the conditions are favorable for a population at low density,such as when a species colonizes a new environment,population growth is typically

A)exponential.
B)logistic.
C)tangential.
D)dynamic.

Question 15

Populations inhabiting favorable environments at low population densities typically experience ________ population growth,resulting in a continuously accelerating rate of population increase.

Question 16

A(n)________ distribution refers to the proportion of individuals in the various age classes for any one year.

Question 17

A group of individuals born in the same period of time is called a(n)________.

Question 18

Which of the following equations reflects the exponential model of population growth?

A)N(t)= b - d
B)s = ΔN / Δt
C)N(t)= N(0)ert
D)dN / dt = rN

Question 19

The net reproductive rate (R0)is equal to ________ when females,on average,replace themselves in a population.

Question 20

Ecologists develop a(n)________ life table to follow the fate of a group of individuals,who were all born at a given time,from birth to death.

Question 21

Age-specific mortality is defined as the

A)difference between the number of individuals alive for any age class and the next older age class.
B)number of individuals that died during any given time interval divided by the number alive at the beginning of that interval.
C)number of individuals from the original cohort who are alive at the specified age.
D)probability at birth of surviving to any given age.

Question 22

Most life tables have been constructed for

A)short-lived plants.
B)insects.
C)short-lived vertebrates.
D)long-lived mammals.

Question 23

Survivorship curves plot ________ against x.

A)dx
B)lx
C)log lx
D)qx

Question 24

Why is the b0 = 0 at time period x0 for some species?

A)The birthrate always starts at 0.
B)Some species do not reproduce during the first time period.
C)All individuals are dead at x0.
D)This is the case because m0 times 0 always = 0.

Question 25

A population that is growing has a net reproductive rate (R0)that is

A)= 0.
B)> 0 and < 1.
C)= 1.
D)> 1.

Question 26

qx =

A)nx/dx.
B)nx/lx.
C)dx/nx.
D)Tx/nx.

Question 27

The Dall sheep (a)curve represents which type of survivorship curve?

A)Type I
B)Type II
C)Type III
D)Type IV

Question 28

A dynamic composite life table is different from a dynamic life table it that it uses individuals

A)born over several time periods.
B)born in a single time period.
C)from several different locations.
D)from several different life tables.

Question 29

Calculate L1,given N₁ = 100,N₂ = 50,and n₃ = 10.

A)90
B)50
C)75
D)10

Question 30

What value do mortality rate curves end on?

A)0
B)1)0
C)however many individuals are dead
D)the percentage of the population that dies in the last time period

Question 31

A time-specific life table is constructed by sampling the

A)fate of a group of individuals born at a given time from birth to death.
B)fate of a group of individuals born over several time periods from birth to death.
C)population to obtain a distribution of age classes during a single time period.
D)population to obtain a distribution of age classes during multiple time periods.

Question 32

A systematic compilation of mortality and survival data for a population is called a(n)

A)age pyramid.
B)life table.
C)cohort group.
D)probability summary.

Question 33

The number of births per female of age x is referred to as the

A)crude birthrate.
B)age-specific birthrate.
C)gross reproductive rate.
D)net reproductive rate.

Question 34

Which model of population growth would you employ if reproduction occurs in discrete time periods rather than being continuous?

A)exponential
B)reciprocal
C)logarithmic
D)geometric

Question 35

Which stage has the longest life expectancy?

A)ex = 0
B)ex = 1
C)ex = 2
D)ex = 0.5

Question 36

The average number of female offspring born to a female over her lifetime is referred to as the

A)crude birthrate.
B)age-specific birthrate.
C)gross reproductive rate.
D)net reproductive rate.

Question 37

If survival rates do not vary with age,as in many species of perennial plants,reptiles,adult birds,and rodents,survivorship curves are typically

A)type I.
B)type II.
C)type III.
D)type IV.

Question 38

The net reproductive rate is the sum of what column?

A)lxbx
B)bx
C)lx
D)x

Question 39

The gross reproductive rate is

A)the total number of offspring born to a population.
B)the total number of offspring born to a population each year.
C)the average number of female offspring born in a year.
D)the average number of female offspring born to her over her lifetime.

Question 40

A population reaches a stable-age distribution when the

A)population stops growing.
B)birthrate is less than the death rate.
C)net reproductive rate (R0)is zero.
D)proportion of individuals in each age group remains the same.

Question 41

Which populations are at greatest risk for extinction?

A)very small ones
B)very large ones
C)ones with specific niches
D)ones with extensive habitat ranges

Question 42

The probability of survival and death usually varies with age.

Question 43

The leading cause of current species extinctions is

A)global warming.
B)habitat destruction.
C)hunting.
D)diseases.

Question 44

The instantaneous per capita rate of growth (r)of a growing population is greater than zero.

Question 45

Exponential growth is characteristic of populations that inhabit favorable environments at low densities.

Question 46

The net reproductive rate (R0)refers to the average number of females that will be produced during a lifetime by a newborn female.

Question 47

What is one of the most damaging issues in freshwater systems that has caused the highest number of declines in fish?

A)pollution
B)dams
C)climate change
D)ozone depletion

Question 48

Why are population projection matrices so complicated?

A)because plant sizes are fixed over time
B)because larger populations require more sophistication
C)because fecundity is high in some species
D)because some species can move back and forth between life stages

Question 49

Species with type III survivorship curves experience extremely high mortality rates in early life.

Question 50

Immigration and emigration occur within a closed population.

Question 51

In a given life table,qx represents the age-specific mortality rate.

Question 52

Given λ = 2,what would the intrinsic rate of reproduction (r)be?

A)4
B)0)69
C)1
D)0

Question 53

According to the latest data,which region has the highest number of species recently gone extinct?

A)North America
B)South America
C)Africa
D)Australia

Question 54

In a population projection matrix,S34 would represent

A)the probability an individual in stage class 3 would move to 4.
B)the probability an individual in stage class 4 would revert to 3.
C)the time it takes an individual to move from 3 to 4.
D)the average amount of growth that occurs from stage class 3 to 4.

Question 55

When females form the reproductive unit of a population,what would the population be when one calculates a population of 50 from a life table?

A)100
B)25
C)50
D)200

Question 56

A time-specific life table follows a group of individuals born at a given time from birth to death.

Question 57

If N(0)= 30 and λ = 1.20,what is the population size for year one?

A)25
B)28.8
C)30
D)36

Question 58

A flood wiping out a population would be an example of

A)exponential growth.
B)survivorship curve.
C)demographic stochasticity.
D)environmental stochasticity.

Question 59

The gross reproductive rate represents the number of births per 1000 population per unit of time.

Question 60

Exponential population growth does not occur in natural populations.

Question 61

A population in which λ equals one has reached a stable-age distribution.

Question 62

Environmental stochasticity refers to random variations in birth and death rates occurring in populations from year to year.

Question 63

The introduction of a novel organism into an ecosystem can lead to the extinction of species.