Chapter Fifty-Three – Flashcards
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1. What two pieces of data are needed to mathematically determine density?
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number of individuals per unit area or volume
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2. What is the difference between density and dispersion?
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dispersion: pattern of spacing among individuals within boundaries of pop
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Note and understand what the letters of the formula mean. Next, try the following problem.
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N=mn/x N=estimated pop size m= number of individuals parked and released in first sampling n=total number of individuals captured 2nd time x= number of marked animals recaptured in the second sampling
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4. Explain the impact of immigration and emigration on population density. (To avoid confusion between these two terms, it might help to use this memory trick: immigration is the movement into a population, while emigration is the exiting of individuals from a population.)
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immigration: increase density (like births) emigration: decreases density (like deaths)
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5. Label the dispersion pattern shown by each population in the figure below. Second, and most important, what do the dispersion patterns tell us about the population and its interactions?
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clumped: group where food is uniform: maintained by aggressive interactions btw neighbors random: mostly plants. random spreading of seeds
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6. In what population statistic do demographers have a particular interest? How is this data often presented?
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birth and death rates. summarize population size growth. presented in life table
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7. Is your biology class a cohort? Explain.
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cohort: group of individuals of the same age, from birth until al are dead.
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8. Survivorship curves show patterns of survival. In general terms, survivorship curves can be classified into three types. Using the figure below, label and explain the three idealized survivorship patterns.
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Type 1: most live to average lifespan. few offspring, well cared for. K-selected Type 2: constant death rate. K-selected Type 3: a lot die initially. release lots of eggs, no parenting, few survive. R-selected
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10. What does a reproductive table show?
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age-specific summary of reproductive rates in a population. Number of female offspring produced by each age group (in sexual species)
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11. On what is the life history of an organism based?
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The traits that affect an organisms schedule of reproduction and survival from birth to death.
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12. What three variables form the life history of a species?
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-when reproduction begins -how often organism reproduces - how many offspring are produced.
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13. Explain the difference between semelparity (big-bang reproduction) and iteroparity (repeated reproduction) as life history strategies.
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semelparity : single reproductive episode before death (release eggs). can wait for right conditions, release a lot. survival rate of offspring is low. iteroparity: multiple reproductive cycles over the course of its lifetime. more dependable environments.
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14. Explain how two critical factors influence whether a species will evolve toward semelparity or iteroparity.
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survival rate of offspring, likelihood that the adult will survive to reproduce again
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15. Explain the effect of offspring care on parental survival in kestrels.
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...
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Do not let the math in this section be a problem. Instead of trying to understand the calculus involved, concentrate on the idea of exponential growth, how it is graphed, and what this type of growth indicates about a population.
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...
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16. What is the advantage to using per capita birth and death rates rather than just the raw numbers of births and deaths?
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per capita birth rate: number of offspring produced per unit time by an average number of the population
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17. What will the per capita birth and death rates be if a population is demonstrating zero population growth?
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equal
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18. What does it mean for a population to be in exponential population growth?
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ideal conditions: access to abundant food, free to reproduce at capacity. per capita rate of increase=max
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19. In the graph below, explain why the line with the value of 1.0 shows a steeper slope that reaches exponential growth more quickly than does the line with the value of 0.5. On this graph, add a third line that approximates a population with an exponential value of 1.25.
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different maximum per capita rates==different slopes
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20. What are two examples of conditions that might lead to exponential population growth in natural populations?
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no predators. protected species, humans
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21. What is carrying capacity?
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maximum population size that a particular environment can sustain. K
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22. What are six examples of limiting resources that can influence carrying capacity?
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energy shelter refuge from predators nutrient availability water suitable nesting sites
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23. In the logistic population growth model, the per capita rate of increase approaches zero as the __________________________ is reached.
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carrying capacity
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24. If the carrying capacity (or K) is 1,000 and N is 10, the term (K - N)/K is large. Explain why a large value for (K - N)/K predicts growth close to the maximum rate of increase for this population.
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environment can sustain more, rate will be high
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25. In the graph below, explain why the logistic model predicts a sigmoid (S-shaped) growth curve when the population density is plotted over time. Hint: The critical part of this answer concerns why growth slows as N approaches K.
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new individuals are added to the population most rapidly at intermediate population sizes. pop growth slows as N approaches K
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26. The end of this concept attempts to bring together the ideas of life histories and growth models This is done with the introduction of two new terms: K-selection and r-selection. Explain the ideas behind the creation of these two terms.
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k-selection: density-dependent selection. selection for life history traits that are sensitive to population. operates on populations near density limit imposed by resources and competition is strong. r-selection: selection for life history traits that maximize reproductive success in uncrowded environments. ex. disruption of habitats.
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27. Compare and contrast these two terms: density-independent regulation density-dependent regulation
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density-independent regulation: a birth rate or death rate that does not change with population density density-dependent regulation: death rate that rises with pop density
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28. Explain how negative feedback plays an essential role in the unifying theme of regulation of populations. Does negative feedback play a role in both density-independent and density-dependent regulation?
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density decreases pop growth. or else pops wouldnt stop growing
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Negative Feedback Mechanisms
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Competion for resources Territoriality-limits density. compete for territory Disease- spread with crowding. Predation-if predator captures more food as density of prey increases Toxic wastes-metabolic waste can poison. Intrinsic factors- (physiological/internal) aggressive interactions/stress with crowding can decrease reproduce rate
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30. Give both biotic and abiotic reasons for population fluctuations over the last 50 years in the moose population on Isle Royale, based on population dynamics.
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weather/seasons predation
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31. Explain the importance of immigration and emigration in metapopulations.
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link populations
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32. Summarize human population growth since 1650.
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exponential growth
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33. What is demographic transition? Use the figure below to explain the process in Sweden and Mexico.
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when birth rates approach death rates. associated with increased health care, sanitation, access to education (esp women)
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34. You should be able to look at age-structure graphs and make predictions about the future growth of the population. Using Figure 53.25, describe the key features for the three age-structure graphs and predict how the population of each country will grow. Country Key Features Predicted Future Growth
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age structure: relative number of individuals of each age in a population
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35. Why do infant mortality and life expectancy vary so greatly between certain countries?
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reflect quality of life.
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36. Can the world's population sustain an ecological footprint that is currently the average American footprint? Explain.
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NO
