Chapter 52 Population Ecology Answer Guide

Interactive Questions

52.1 What is the likely dispersion pattern of fish that swim in school, seabirds nesting on a small island, and thistles growing in a fairly uniform field?

Clumped; uniform; random

52.2 Identify the types o survivorship curves shown blow and give examples of specifes that exhibit each curve.

a. Type I, humans and many large mammals

b. Type II, Belding’s ground squirrels and some other rodents, some annual plants, various invertebrates, and some lizards.

c. Type III, man fishes and marine invertebrates such as oysters, long-lived plants

52.3 a. Explain why the life history of an organism can’t be reproduce early, often, have large numbers of offspring and live long.

a. An organism has limited resources to divide between growth, survival and reproduction.

52.3 b. In what way might high competition for limited resources in a predictable environment influence life history traits?

b. Selection would most likely favor iteroparity, with fewer, larger, better-provisioned or cared-for offspring.

52.4 Label the exponential and logistic growth curves, and show the equation associated with each curve. What is K for the population shown with curve b?

a. exponential grow; dN/dt = rN

b. logistic growth; dN/dt = rN(K – N)/K; Kis 1500

52.5 Indicate whether the following would be considered to be r-selected or K-selected life history traits.

a. Early age at first reproduction; many small offspring produced

a. r-selected

b. few, relatively large offspring produced every year

b. K-selected

52.6 a. List some density dependent factors that may limit population growth.

a. nutrients, space for nests, accumulation of toxic wastes, predation, intrinsic limiting factors

52.6 b. List some abiotic factors that may cause population fluctations.

b. extremes in weather, natural disasters, fires

Structure Your Knowledge

1.

2. Reproductive success is measurd in the number of offspring that survive and live to reproduce. Many “choices” are available in life history traits: big-bang versus repeated reproduction, age at first reproduction, number of reproductive episodes, number of offspring or care. There are always trade-offs between reproduction and survival due to limited energy budgets. Considering hat diverse environments (with both biotic and abiotic factors) and different population densities (K or r-selection) create different selection pressures on a population, there is no one “best” reproductive strategy.

Multiple Choice

  1. a; clumped; 1138
  2. c; ecologists have collected them for large # of natural populations; 1139
  3. d; semelparity or big-bang reproduction; 1141
  4. b; typical of humans and other large mammals; 1140
  5. e; is the period when the population growth rate is the highest; 1145
  6. d; a, b, and c may apply; 1147
  7. c; is 0 when population size equals carrying capacity; 1145
  8. d; a very early fall frost; 1149
  9. c; 8; 1144
  10. d; maintain the population density close to .5K; 1145
  11. e; all of the above are true; 1150
  12. a; metapopulations; 1151
  13. b; decrease; 1148-1150
  14. a; increase; 1148-1150
  15. a; increase;1148-1150
  16. e; hare population is regulated by food/predators; lynx population appears to cycle in response to hare availability that of the hare; 1148
  17. d; high birth rates and high death rates to low birth & death rates; 1155
  18. c; the amount of land needed per person to meet current demand on resources; 1155