Chapter 12 (11): Population Growth and Regulation
Doubling time (td)
0.69/r
λ
1+B-D
__________ is the study of populations
Demography
The earlier work of __________ on population growth had a profound influence on Darwin as he developed his ideas regarding the great potential for expansion of populations in the face of limited resources.
Thomas Malthus
A logistic growth model assumes population growth is density‐__________. A) dependent B) independent C) neutral
a
A static life table is developed by determining: A) the survival of individuals of known age during a single time interval. B) the survival of individuals of known age across multiple time intervals. C) the lifetime pattern of survival of individuals belonging to a particular cohort. D) none of the above
a
Density‐independent factors can influence the growth rate of a population, but they do not regulate its size. A) True B) False
a
For any population with a stable age distribution, the proportion of the total population in each age class remains unchanged from one time interval to the next. A) True B) False
a
Population growth rates sometimes increase with increasing population density, especially at low population densities, as seen in certain fish stocks. We refer to this kind of population response as __________. A) positive density dependence B) negative density dependence C) juvenile recruitment D) self‐thinning
a
The human population of East Overshoe does not presently have a stable age distribution, but its age‐specific survival and fecundity schedules have remained constant for the past several years. If these schedules remain constant into the future, will this population eventually reach a stable age distribution? A) Yes B) No
a
When a population grows according to the logistic model, at what population size does dN/dt equal zero? A) N = K B) N = K/2 C) N = r0 D) N = infinite
a
Which of the following equations is used to project population size through time, under conditions of exponential growth? A) N(t) = N(0)ert D) λ = er B) N(t) = N(0) λt E) r = b ‐ d C) dN/dt = rN F) λ = 1 + B ‐ D
a
Which of the two approaches below would be best suited to modeling human population growth? A) continuous‐time B) discrete‐time
a
Which stages of life in a population are often found to suffer more from the adverse effects of density‐dependent factors? A) juvenile stages B) adult stages C) both juvenile and adult stages about equally
a
You are a demographer working for the United Nations. You construct age structure pyramids for two neighboring countries, Upper and Lower Demographia. The age structure pyramid for Upper Demographia has a broad base, while that for Lower Demographia has a narrow base. Which of these countries most likely has a growing population? A) Upper Demographia B) Lower Demographia
a
When a population assumes a __________, each age class in the population grows or declines at the same rate.
age distribution
Each population has a(n) __________, defined by the proportions of individuals in the various age classes.
age structure
. In an exponentially (N(t) = N(0)ert) or geometrically (N(t) = N(0) λt) growing population with constant r or λ, is population stability ever reached? A) Yes, the population stops growing when resources or some other extrinsic factors become sufficiently limiting. B) No, a population growing in this fashion exhibits unrestricted growth.
b
For any population with a stable age distribution, λ is 0. A) True B) False
b
In the life table for the pied flycatcher, Ficedula hypoleuca, the survival rate (sx) for age class x = 3 is s3 = 0.490. What does this mean, in words? A) For a cohort of 777 individuals alive at age 1, 381 will be alive at age 4. B) For a cohort of 204 individuals alive at age 3, 100 will be alive at age 4. C) The survivorship (lx) for age 3 is 0.490. D) The expectation of further life (ex) for age 3 is 0.49 years.
b
In the life table for the pied flycatcher, Ficedula hypoleuca, the survivorship value for age class x = 3 is l 3 = 0.263. What does this mean, in words? A) For a cohort of 777 individuals alive at age 1, 263 will be alive at age 3. B) For a cohort of 777 individuals alive at age 1, 204 will be alive at age 3. C) The survival rate (sx) for age 3 is 0.263. D) The mortality rate (mx) for age 3 is 1 ‐ 0.263 = 0.737.
b
Select from the following list the author who first wrote: "As more individuals are produced than can possibly survive, there must in every case be a struggle of existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life. It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there can be no artificial increase of food, and no prudential restraint from marriage. Although some species may be now increasing, more or less rapidly, in numbers, all cannot do so, for the world would not hold them." A) Robert Ricklefs C) Thomas Malthus B) Charles Darwin D) Thomas Wentworth
b
The computed doubling time for Italy is ‐690 years. What does this actually mean? A) The population of Italy will double in 690 years. B) The population of Italy will be halved in 690 years. C) A negative number for doubling time has no meaning.
b
The elephant seal made a remarkable recovery from the brink of extinction, increasing from 100 individuals in 1900 to 150,000 in 2000. The value of r for this species over this time period was 0.073 per capita per year. What was the doubling time for this species? (0.693/r) A) 7.3 years B) 9.45 years C) 1500 years D) Doubling time cannot be determined from the data provided.
b
The elf‐orpine, a tiny plant that grows in shallow depressions on granite rock outcrops of the southeast, is a winter annual. Seeds are shed in early fall and germinate in moist patches of shallow sand. The plants grow slowly through the winter. They mature, flower, and produce seeds during the spring. The plants then die, but seeds are retained on the dead plants until early fall. Which of the two approaches below would be best suited to modeling population growth of the elf‐orpine? A) continuous‐time B) discrete‐time
b
The value of λ for Italy is slightly less than 1.0. What does this imply? A) The population of Italy is increasing. B) The population of Italy is decreasing. C) The population of Italy is stable.
b
When a population grows according to a logistic model, at what size is its growth rate maximal? A) N = K B) N = K/2 C) N = r0 D) N = infinite
b
When a population grows according to the logistic model, what is the value of r when the population is stable? A) r = r0 B) r = 0 C) r = K D) r = N
b
Which of the following equations is used to project population size through time, under conditions of geometric growth? A) N(t) = N(0)e^(rt) D) λ = er B) N(t) = N(0)λ^t E) r = b ‐ d C) dN/dt = rN F) λ = 1 + B ‐ D
b
A cohort life table is developed by determining: A) the survival of individuals of known age during a single time interval. B) the survival of individuals of known age across multiple time intervals. C) the lifetime pattern of survival of individuals belonging to a particular cohort. D) none of the above
c
A declining population of an endangered butterfly is determined to have an exponential rate of decrease of r = ‐0.02. What is the corresponding value of λ for this population? A) greater than 1 D) exactly 0 B) exactly 1 E) less than 0 C) greater than 0 and less than 1
c
How is r related to r0 in the logistic model of population growth? A) r = r0N B) r = r0N(1 ‐ N/K) C) r = r0(1 ‐ N/K) D) r = r0
c
If you wanted instead to use the logistic model of population growth to determine dN/dt for the population of the Democratic Republic of the Congo, which of the following formulae would you choose? A) dN/dt = rN B) N(t) = N(0)ert C) dN/dt = r0N(1 - (N/K)) D) N(t) = N(0)λt E) N(t+1) = N(t)λ
c
Of 608 Dall mountain sheep alive at birth, Olaus Murie determined that 154 were alive at the beginning of age interval x = 10‐11. What did he determine to be the survivorship (l 10) for this species? A) 0.10 B) 0.154 C) 0.253 D) 0.608 E) 154
c
When a population grows according to a logistic model, what happens if the population exceeds carrying capacity? A) The population resumes exponential growth. B) The size of the population remains constant. C) The size of the population begins to decline. D) The population goes extinct.
c
Which of the following equations describes the rate at which individuals are added to or removed from a population exhibiting exponential growth? A) N(t) = N(0)ert D) λ = er B) N(t) = N(0) λt E) r = b ‐ d C) dN/dt = rN F) λ = 1 + B ‐ D
c
A __________ is a group of organisms belonging to a particular species, all born at the same time, and followed throughout their lives for purposes of life‐table development.
cohort
A local population of Japanese beetles is growing geometrically with λ = 1.1. The population on July 31 this year consists of 800 adults. How many adults will be in this population on July 31 in two years? A) 800 B) 880 C) 960 D) 968 E) 1100
d
Considering the growth of the human population from the development of agriculture 10,000 years ago to the present, which of the following has had the most lasting effect on population dynamics? A) war B) famine C) disease D) Industrial Revolution
d
Studies of many plant populations show that, as plants grow larger and experience crowding, some plants die while the survivors grow larger. When average dry weight per plant is plotted against the number of surviving plants (both on log scales) the result is a linear relationship with negative slope, described by the __________. A) -1/4 power law B) -1/2 power law C) -3/4 power law D) -3/2 power law
d
The mammalogist Olaus Murie developed a well‐known life table for Dall mountain sheep using which of the following types of evidence? A) survival patterns of a cohort that he monitored over a 15‐year period B) the survival of individuals of known age during a single year C) the survival of individuals of known age over a 15‐year period D) age at death determined from skeletal remains
d
Which of the following equations shows the relationship between the key parameters of the exponential and geometric models for population growth? A) N(t) = N(0)e^rt D) λ = e^r B) N(t) = N(0) λ^t E) r = b ‐ d C) dN/dt = rN F) λ = 1 + B ‐ D
d
__________ factors, such as weather and catastrophic events, affect population birth and death rates, but ultimately cannot regulate population size.
density-independent
Which of the following equations illustrates the dependence of the per capita contribution to population growth on per capita birth and death rates in the exponential model for population growth? A) N(t) = N(0)ert D) λ = er B) N(t) = N(0) λt E) r = b ‐ d C) dN/dt = rN F) λ = 1 + B ‐ D
e
It is possible to approximate the intrinsic rate of increase (λm or rm) from life table data by deriving λa or ra. Which of the following must be determined in order to derive λa or ra? A) survival rates (sx) D) generation time (T) B) expectations of life (ex) E) both A and B C) net reproductive rate (R0) F) both C and D
f
Which of the following equations illustrates the dependence of the per capita contribution to population growth on per capita birth and death rates in the geometric model for population growth? A) N(t) = N(0)ert D) λ = er B) N(t) = N(0) λt E) r = b ‐ d C) dN/dt = rN F) λ = 1 + B ‐ D
f
In life table analysis, the __________ of females is typically defined as the number of female offspring produced per breeding season or age interval.
fecundity
In the logistic model of population growth, the __________ separates the early accelerating phase of population growth from the later decelerating phase.
inflection point
r
ln(λ)
The flexibility of their growth, coupled with density‐induced mortality, results in striking patterns of density‐dependence in growth of __________, described by the self‐thinning curve
plants
In life table analysis, __________ for any age class x may be computed as the product of a series of survival rates, s0s1s2...sx‐1.
survivorship
