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Ecology Exam 9/12
Ecology exam, chapters 8 through 12
| Question | Answer |
|---|---|
| A dynamic composite life table is different from a dynamic life table it that it uses individuals ________ | born over several time periods. |
| A fecundity table for a gray squirrel: x lx bx lxbx 0 1.0 0.0 0.00 1 0.3 2.0 0.60 2 0.15 3.0 0.45 3 0.09 3.0 0.27 4 0.04 2.0 0.08 5 0.01 0.0 0.00 On the basis of these calculations, the net reproductive rate (R0) is equal to ____ | 1.4 (add all of the totals in the Lxbx column) |
| A flood wiping out a population would be an example of what? | environmental stochasticity |
| A population reaches a stable-age distribution when the _____ | proportion of individuals in each age group remains the same |
| A population that is growing has a net reproductive rate (R0) that is _____ | > 1 |
| A population that is increasing in size has an intrinsic rate of population growth (r) that is ____ | > 0 |
| A systematic compilation of mortality and survival data for a population is called a(n) _____ | life table |
| A time-specific life table is constructed by sampling the ___ | population to obtain a distribution of age classes during a single time period |
| According to the latest data, which region has the highest number of species recently gone extinct? a. South America b. North America c. Africa d. Australia | b. North America |
| Age-specific mortality is defined as the ... | difference between the number of individuals alive for any age class and the next older age class |
| Calculate L1, given n1 = 100, n2 = 50, and n3 = 10. | 75 (Equation: L1 = (N1 + N2)/2 |
| Given λ = 2, what would the intrinsic rate of reproduction (r) be? | 0.69 (it would be ln(λ) in calculator) |
| If N(0) = 30 and λ = 1.20, what is the population size for year one? | 36 ( equation: N(1) = N(0) * λ) |
| If survival rates do not vary with age, as in many species of perennial plants, reptiles, adult birds, and rodents, survivorship curves are typically type ___ | Type II |
| In a population projection matrix, S34 would represent what? | the probability an individual in stage class 4 would revert to 3. |
| Most life tables have been constructed for what? | long-lived mammals |
| Finish the equation: qx = ______ | dx/nx. |
| Survivorship curves plot ________ against x. | Lx |
| The average number of female offspring born to a female over her lifetime is referred to as the ____ | Gross reproductive rate |
| The Dall sheep (a) curve represents which type of survivorship curve? | Type 1 |
| The gross reproductive rate is what? | the average number of female offspring born to her over her lifetime |
| The leading cause of current species extinctions is what? | habitat destruction |
| The net reproductive rate is the sum of what column? | lxbx |
| The number of births per female of age x is referred to as the ____ | age-specific birthrate |
| The pattern shown in figure 9.6 best resembles what? (it starts at zero and has the look of half of a U) | exponential growth |
| What is one of the most damaging issues in freshwater systems that has caused the highest number of declines in fish? | dams |
| What value do mortality rate curves end on? | 1.0 |
| 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? | 100 |
| When the conditions are favorable for a population at low density, such as when a species colonizes a new environment, population growth is typically what? | Exponential |
| Which model of population growth would you employ if reproduction occurs in discrete time periods rather than being continuous? a. geometric b. logarithmic c. exponential d. reciprocal | a. geometric |
| Which of the following equations reflects the exponential model of population growth? a. N(t) = N(0)e^rt b. dN / dt = rN c. N(t) = b - d d. s = ΔN / Δt | a. N(t) = N(0)e^rt |
| Which populations are at greatest risk for extinction? a. ones with specific niches b. very large ones c. ones with extensive habitat ranges d. very small ones | d. very small ones |
| Which stage has the longest life expectancy? a. ex = 2 b. ex = 0.5 c. ex = 1 d. ex = 0 | a. ex = 2 |
| Why are population projection matrices so complicated? | because some species can move back and forth between life stages |
| Why is the b0 = 0 at time period x0 for some species? | Some species do not reproduce during the first time period. |
| ______ is the study of populations | Demography |
| ______ stochasticity is the random variation in birth and death rates that occurs in populations from year to year | Demographic |
| _______ 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 variation in the environment | Environmental |
| A group of individuals born in the same period of time is called _____ | cohort |
| A population eventually becomes ______ when its population growth (r) remains negative without reversing | Extinct |
| A type ___ survivorship curve is typically of populations in which individuals tend to live out their physiological life span. | I |
| A _____ distribution refers to the proportion of individuals in the various age classes for any one year. | Age |
| A _____ life table is constructed by sampling the population to obtain a distribution of age classes during a single time period. | Time-specific |
| A _____ curve plots the probability at birth of surviving to any given age (lx) against time or age class (x). | survivorship |
| Ecologists develop a ___ life table to follow the fate of a group of individuals, who were all born at a given time, from birth to death | Cohort or dynamic |
| Life ________ refers to the average number of years that an individual is expected to live from the time of his or her birth. | expectancy |
| Movement in and out of a population occurs in a(n) _____ population | open |
| Population _____ refers to the rate at which the number of individuals in a population increases or decreases with time. | Growth |
| Populations inhabiting favorable environments at low population densities experience _____ population growth, resulting in a continuously accelerating rate of population increase | exponential |
| Rodents typically exhibit a type ____ survivorship curve. | II |
| The ____ birthrate is expressed as the births per 1000 individuals per unit of time. | crude |
| The net reproductive rate (Ro) is equal to ______ when females, on average, replace themselves in a population | one |
| There is no change in population size when the instantaneous per capita rate of growth (r) is equal to ____ | zero |
| T/F: A population in which λ equals one has reached a stable-age distribution. | True |
| T/F: A time-specific life table follows a group of individuals born at a given time from birth to death. | False |
| T/F: Environmental stochasticity refers to random variations in birth and death rates occurring in populations from year to year. | False |
| T/F: Exponential growth is characteristic of populations that inhabit favorable environments at low densities. | True |
| T/F: Exponential population growth does not occur in natural populations. | False |
| T/F: Immigration and emigration occur within a closed population. | False |
| T/F: In a given life table, qx represents the age-specific mortality rate. | True |
| T/F: Species with type III survivorship curves experience extremely high mortality rates in early life. | True |
| T/F: The gross reproductive rate represents the number of births per 1000 population per unit of time. | False |
| T/F: The instantaneous per capita rate of growth (r) of a growing population is greater than zero. | True |
| T/F: The introduction of a novel organism into an ecosystem can lead to the extinction of species. | True |
| T/F: The net reproductive rate (R0) refers to the average number of females that will be produced during a lifetime by a newborn female. | True |
| T/F: The probability of survival and death usually varies with age. | True |
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phebe
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