Test 3 study guide

Question 1

Make sure to read and understand the “Applying Population Ecology: The Human Population” handout that was given to you for your take-home assignment.

Question 2

Explain how highly developed and developing countries differ in population characteristics such as infant mortality rate, total fertility rate, replacement-level fertility, and age structure.

Answer 2

Highly developed countries have lower infant mortality rate, lower fertility rate, but people are living longer so the replacement-level fertility would be lower then in developing countries. The opossite is true for developing countries.

Question 3

Distinguish between people overpopulation and consumption overpopulation

Answer 3

People being born is producing over population in a given area creating a deplition of resources to support the population. Where consumption overpopulation is the over consumption of natural resources.

There may be over population but also people in developed countries use more then the rest of the world combined. It is a double edge sword.

Question 4

Define population ecology~what do population ecologists study?

Answer 4

• Population ecology: the study of populations (the numbers of individuals of a particular species at a given time and location), and their interactions with the environment.
• every living thing on this planet is studied by ecologists.
• environmental systems.
• Biotic factors
• abiotic factors

Question 5

• Describe the demographics of populations and understand that physical and temporal boundaries must be defined:
  
  • population density
  • dispersion(uniform, clumped, random and examples of when each will be used)
  • life tables, reproductive tables, age structure
    
    • understand how to read each of these and what information they provide

Answer 5

• population density - how many individuals in a given space
• dispersion
  
  • uniform - like penguins during nesting, due to territorial
  • clumped - geese, or starfish, or school of fish. due to food or protection
  • random - wild flowers or dandilion. no pattern showing in location
• life tables - an age-specific summary of the survival pattern of a populationi.Used to estimate how long, on average, an individual of a given age could be expected to live.
  
  • The best way to construct a life table isto follow the fate ofa cohort.a.Cohort:a group of individuals of the same agefrom birth until all of the individuals are dead.b.Example, life table of Belding’s ground squirrelsprovides data on the proportions of males and females alive at each age
• reproductive tables - (fertility schedule) is an age-specific summary of the reproductive rates in a population
• age structure - the relative number of individuals of each age in a population.
  
  • A broader base to the age structure indicates a growingpopulation
  • Anarrower base indicates a stable or shrinking population

Question 6

Describe Type I, Type II, and Type III survivorship curves, and explain how life tables and survivorship curves indicate mortality and survival.

Answer 6

• Type I Curve: low death rates during early and middle life(flat curve at the start)and an increase in death rates among older age groups(curve drops steeply)
  
  • Type I curves are characterized by high mortality late in life.
  • Humans and other large mammals exhibit Type I curve as they produce few offspring but provide them with good care
• Type II Curve: a constant death rate over the organism’s life span
  
  • Some birds and lizards, Belding’s ground squirrels, other rodents
• Type III Curve: high death rates for the young(curve drops steeply at the start) and a lower death rate for survivors(curve flattens out)
  
  • Type III survivorship is characterized by high mortality early in life
  • Associated with organisms that produce large numbers ofoffspring but provide little or no care(e.g. many plants, many fish, most marine invertebrates)

Question 7

• Explain the four factors (natality, mortality, immigration, and emigration) that produce changes in population size, and solve simple problems involving these changes. I will give you the following formulas,but understand how to use them.
  
  • dN/dt = rN
  • r = b –m
  • dN/dt = bN –mN
  • dN/dt = (B+i) –(D+e)

Answer 7

• dN/dt = (B+i) –(D+e)
  
  • the total change in the population. Take this add to the population (N) give you the current population
• dN/dt = rN
  
  • the total change in the population (TCP) is the same as dN/dt
  • so taking TCP divided into the total starting population (N)
  • equals r
• dN/dt = bN –mN
  
  • (B+i) –(D+e) = (B+i) –(D+e) = dN/dt
  • the total change in the population. Take this add to the population (N) give you the current population
• r = b – m
  
  • b is the rate of births per individual so if it says 10 births per 1000 the b would be .01
  • m is the rate of births per individual so if it says 7 births per 1000 the m would be .007
  • greater than 0 population is increasing.
  • less than 0 population is decreasing
  • equal to 0 the population is zero population growth

Question 8

Define exponential growth, logistic growth and carrying capacity, and explain the differences between J-shaped and S-shaped growth curves. What are factors that influence carrying capacity?

Answer 8

• exponential growth
  
  • the growth with idealist conditions the growth allowed in an area
  • J-shaped curve
• logistic growth
  
  • is the growth that levels off at it’s carrying compacity
  • s-shaped growth curve
• carrying capacity
  
  • It varies with the abundance of limiting resources

Question 9

Contrast the influences of density-dependent and density-independent factors on population size, and give examples of each.

Answer 9

• density-dependent
  
  • Density-dependent factors are those which increase in proportional effect with increasing population size
    
    • Many populations are regulated by multiple density-dependent factors
      
      • Competition for resources
      • Toxic Wastes
      • Predation
        
        • As a prey population builds up, predators may feed preferentially on that species
      • Intrinsic (physiological) Factors
      • Territoriality
        
        • in many vertebrates and some invertebrates, competition for territory may limit density
      • Disease
        
        • Population density can influence the health and survival of organisms
        • In dense populations, pathogens can spread more rapidly
• density-independent
  
  • Environmental factors which affect population regardless of size are density-independent factors.
  • Many climatic factors are density-independent.

Question 10

Understand what is meant by “life history” and contrast semelparous and iteroparous reproduction.

Answer 10

• Life history: the traits that affect an organism’s schedule of reproduction and survival.
  
  • Sometraitsinclude: when reproduction begins (age of sexual maturity), how often the organism reproduces,how many offspring are produced per reproductive episode, parental care giving
  • Types of life histories:
  • Semelparity (big-bang reproduction): reproduction in which an organism produces all of its offspring in a single event
    
    • Favored by highly variable or unpredictable environments
    • Offspring are usually small and numerous
  • Iteroparity(repeated reproduction): reproduction in which an organismproducesoffspring over many years(repeatedly)
    
    • Favored by dependable environments
    • Offspring are usually large and fewwith parental careiii.Life histories exist as intermediates between the two extremes of semelparity and iteroparity

Question 11

Distinguish among species exhibiting an r strategy, those with a K strategy, and those that do not easily fit either category.

Answer 11

• R-strategists: organisms thatpossesstraits to increase the growth rate(r)
  
  • typicallyhave a high r(growth rate), are smaller insize, have large numbers of offspring, and may live in unpredictable habitats(usually exhibit Type III survivorship curve)
  • Oysters, weeds,pest species are r-strategists.
  • Many r-strategists reproduce asexually.
  • r-selection(density-independent selection): selects for life history traits that maximize reproductive success in uncrowded environments(abandoned agriculture field or burned area)
• K-strategists: organisms that possess traits to ensure that the population of a species doesn’t exceed the carrying capacity.
  
  • Typicallyhave a population size near K, are larger in size, have fewer offspring, and may care for their young.(usually exhibit Type I survivorship curve)
  • birds, elephants, horses, gorillas and some plants are K-strategists
  • K-strategiststypically live in stable environments.
  • K-selection(density-dependent selection): selects for life history traits that are sensitive to population density