Population Ecology Quiz
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Questions and Answers

What is the main characteristic of Type III survivorship?

  • Constant death rates across all age groups
  • Low mortality rates in young
  • Parental care leading to high survival rates
  • High mortality for the young followed by a plateau in adults (correct)

    • In exponential population growth, which factor does NOT influence the change in population size?

  • Industrial pollution (correct)
  • Number of deaths
  • Number of immigrants
  • Number of births

    • What denotes the carrying capacity (K) in a habitat?

  • The number of individuals that can migrate to a new area
  • The maximum population size that can be sustained (correct)
  • The point at which resources are infinite
  • The initial population size before growth starts

    • Which equation represents the change in population size over time?

    <p>$ rac{dN}{dt} = B + I - D - E$</p> Signup and view all the answers

    Which of the following best describes exponential growth?

    <p>Characterized by a J-shaped growth curve</p> Signup and view all the answers

    What does 'r' represent in the context of population growth?

    <p>Intrinsic growth rate of a single individual</p> Signup and view all the answers

    Which scenario is most likely to lead to exponential population growth?

    <p>A population rebounds after a catastrophic event</p> Signup and view all the answers

    What is primarily responsible for limiting logistic growth?

    <p>Finite resources</p> Signup and view all the answers

    What is the first step in the mark-recapture method for estimating population size?

    <p>Mark all sampled individuals</p> Signup and view all the answers

    Which formula is used to estimate the population size in the mark-recapture method?

    <p>$N = \frac{m imes s}{r}$</p> Signup and view all the answers

    What is a key assumption made in mark-recapture methods?

    <p>Marked individuals have mixed completely back into the population.</p> Signup and view all the answers

    What does the variable 's' represent in the mark-recapture method?

    <p>Number of individuals initially sampled</p> Signup and view all the answers

    Which of the following factors contribute positively to changes in population size?

    <p>Immigration and births</p> Signup and view all the answers

    After marking and releasing individuals, what is the next action to take in the mark-recapture process?

    <p>Resample r individuals</p> Signup and view all the answers

    What is the purpose of counting the number m of re-sampled marked individuals?

    <p>To estimate the total population size N</p> Signup and view all the answers

    What is the primary purpose of a life table in demographics?

    <p>To summarize survival and reproduction rates of different age groups.</p> Signup and view all the answers

    Which of the following statements accurately reflects the mark-recapture method?

    <p>It relies on extrapolation from a sub-sample for population size estimation.</p> Signup and view all the answers

    Which type of survivorship curve is characterized by a low death rate in juveniles and adults?

    <p>Type I</p> Signup and view all the answers

    What is demography primarily concerned with studying?

    <p>Changes over time in the vital statistics of populations.</p> Signup and view all the answers

    Why is it often impossible to count all individuals in a population?

    <p>Individuals might be too dispersed or hidden.</p> Signup and view all the answers

    Which characteristic is NOT associated with K-selection?

    <p>Have many offspring at a time</p> Signup and view all the answers

    What do K-selection strategies generally favor?

    <p>Late age of first reproduction</p> Signup and view all the answers

    What is one common misconception regarding K and r strategies?

    <p>They are used by all ecologists today</p> Signup and view all the answers

    In the context of life history trade-offs, which statement is true regarding r strategies?

    <p>They have many small offspring</p> Signup and view all the answers

    What factor may influence the evolution of life-history traits according to the recent understanding in ecology?

    <p>Total amount of resources individuals acquire</p> Signup and view all the answers

    What does the logistic growth model express?

    <p>The relationship of population growth to carrying capacity</p> Signup and view all the answers

    Which statement best describes competition in K-selection environments?

    <p>High competition due to density-dependent effects</p> Signup and view all the answers

    Which of the following is an example of a K-strategy organism?

    <p>Mature trees in an old-growth forest</p> Signup and view all the answers

    What is a life history trait that impacts an organism's schedule of reproduction and survival?

    <p>Age at death</p> Signup and view all the answers

    Which of the following is a characteristic of r-selection life history strategies?

    <p>Mature rapidly</p> Signup and view all the answers

    What is one of the trade-offs observed in life history traits regarding offspring?

    <p>Quality versus quantity of offspring</p> Signup and view all the answers

    In the logistic growth model, what is expected to happen if a population overshoots its carrying capacity K?

    <p>Population crashes due to resource depletion</p> Signup and view all the answers

    Which of the following best describes a phenotypic negative correlation?

    <p>Larger egg sizes correlate with fewer eggs</p> Signup and view all the answers

    What defines the r-selection in population ecology?

    <p>Low density environments with high reproductive output</p> Signup and view all the answers

    Which factor is NOT a life history trait?

    <p>Type of food consumed</p> Signup and view all the answers

    What do life history trade-offs imply about resource allocation?

    <p>Resources must be divided among competing traits</p> Signup and view all the answers

    What does population ecology primarily study?

    <p>The environment's effect on population density and distribution.</p> Signup and view all the answers

    What is the main purpose of the mark-recapture method?

    <p>To estimate population size.</p> Signup and view all the answers

    Which factor is NOT typically analyzed in population dynamics?

    <p>The cost of living in different habitats.</p> Signup and view all the answers

    Which curve is associated with survivorship based on life tables?

    <p>Survivorship curve.</p> Signup and view all the answers

    What is a key difference between exponential and logistic growth models?

    <p>Logistic growth accounts for environmental resistance.</p> Signup and view all the answers

    How can life history traits influence an individual’s fitness?

    <p>By determining the individual's reproductive success.</p> Signup and view all the answers

    Which of the following is true regarding trade-offs in life history traits?

    <p>Investment in one trait reduces investment in another.</p> Signup and view all the answers

    Which method is primarily used to extrapolate population sizes from a sub-sample?

    <p>Mark-recapture method.</p> Signup and view all the answers

    Study Notes

    Topic 15: Population Ecology

    • Population ecology is the study of populations in relation to their environment, including factors like density, distribution, age structure, and population size variation.
    • Population dynamics investigates how biotic and abiotic factors influence population size changes.
    • A population is a group of individuals of a single species living in the same area and interbreeding to produce fertile offspring.

    Learning Outcomes

    • Estimate population size using the mark-recapture method.
    • Graphically analyze population demographics over time.
    • Identify survivorship curves based on demographic parameters from a life table.
    • Compare and contrast exponential and logistic population growth models.
    • Evaluate growth model parameters to predict population size changes.
    • Explain how life history traits impact lifetime fitness.
    • Graphically identify trade-offs in life history traits.

    Estimating Population Size

    • Often, counting all individuals in a population is impossible.
    • A sub-sample is used and extrapolated to estimate the whole population.
    • Mark-recapture method:
      • Sample a number of individuals (s).
      • Mark all sampled individuals.
      • Release the marked individuals.
      • Resample a number of individuals (r).
      • Count the number of re-sampled marked individuals (m).
      • Use the formula N = (s × r) / m to estimate population size (N).

    Population Density

    • Population density is the number of individuals per unit area or volume, and it can change over time.
    • Population density change is influenced by immigration/births and emigration/deaths.
      • Change in population size = births + immigrants - deaths - emigrants

    Demographics

    • Demography is the study of changes in vital statistics over time (like birth rates, death rates) within populations, especially birth rates and death rates.
    • A life table can summarize the survival and reproduction rates of individuals across specific age groups within a population.
    • A life table typically tracks a cohort (individuals born around the same time), particularly females, because they tend to be the ones producing offspring.
    • Life tables reveal constant death rates and higher reproduction rates at specific ages (e.g., age 4 in the Belding's ground squirrel example).

    Survivorship Curves

    • Survivorship curves show the proportion of individuals in a cohort that remain alive at each age.
    • Type I curves show a high survival rate in juveniles and adults, followed by a sharp decline in old age (mammals, few offspring, parental care).
    • Type II curves display a relatively constant death rate across all ages (e.g., certain birds).
    • Type III curves illustrate high mortality rates for young but a leveling off of death rates among surviving individuals into adulthood (fish, many offspring, no parental care).

    Modeling Population Growth

    • Exponential growth occurs in ideal, unlimited environments, where the population size increases by a constant proportion each time interval. The population size over time follows a J-shaped curve.
    • Logistic growth occurs when resources are finite. Initial growth is exponential but slows as the population approaches the carrying capacity (K), the maximum population size a particular environment can sustain, forming an S-shaped growth curve over time. Logistic growth is influenced by environmental limits that affect per capita birth rates and/or death rates

    Life History Traits

    • Life history traits are the characteristics determining the schedule of reproduction and survival in an organism. Examples include:
      • Mass at birth
      • Age at sexual maturity
      • Frequency of reproduction
      • Reproductive lifespan
      • Number of offspring
      • Investment in parental care
      • Age at death (longevity)

    Life History Trade-offs

    • Organisms allocate finite resources to different life history traits, often resulting in trade-offs.
    • Examples include the trade-off between the number of offspring and the resources invested in each offspring. Egg size and fecundity show phenotypic negative correlations.
    • r-selected species (low densities): Short lifespan, high reproductive rate, many small offspring, few reproductive events, high mortality rate, and minimal parental care.
    • K-selected species (high densities): Longer lifespan, low reproductive rate, few large offspring, frequent reproduction, low mortality rate and high parental care

    Summary

    • Population ecology studies populations' relationship to their environment. Key aspects include population dynamics, estimating size, demographics (like survivorship curves), modeling growth (exponential/logistic), life history traits, and trade-offs between them. These factors impact population size over time.

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    Related Documents

    Topic 15 - Population Ecology - BIO1130 PDF

    Description

    Test your understanding of population ecology concepts including population dynamics, size estimation methods, and demographic analyses. This quiz will cover topics such as survivorship curves, growth models, and life history traits. Get ready to evaluate important ecological principles and predict population changes!

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