Graphing: Population Growth Curves

Natural populations all over the world have a variety of factors affecting the growth of their populations. Despite the myriad influences on population growth, graphing the growth of any population or group of populations that interact reveals standard trends of growth that occur in a wide variety of organisms. In this activity you will use real data to visualize these common patterns of growth.

Your task

Construct a total of 3 accurate LINE graphs (data points with lines connecting them) from the data below. The scale and construction are your choice, but you must be exact in your presentation of data or the interpretation of the graphs is impossible. Your graphs must be large enough to be analyzed easily; so several sheets of graph paper are needed to complete all 3 graphs. Put all data from each set on one graph, even when there is more than one organism listed. Use colors and/or different-looking lines to distinguish data on graphs.

  1. growth of yeast

Time (hr.) / 0 / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15 / 16 / 17 / 18
amount of yeast / 5 / 10 / 20 / 30 / 60 / 120 / 200 / 280 / 390 / 450 / 520 / 580 / 600 / 620 / 630 / 635 / 645 / 640 / 660
  1. growth of grain beetles

generations / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10
# of beetles / 10 / 290 / 120 / 260 / 140 / 230 / 160 / 210 / 150 / 180

3.Moose, wolves and balsam fir tree growth on Isle Royale, MI. Isle Royale is an island 22 miles from shore in Lake Superior. It is a national park, but is one of the least visited of all. Ecologists have been studying the interactions of populations for more than half a century. It is known that the wolves prey on the moose and the moose eat the needles from the trees (reducing the tree growth).

*Note—the population of wolves and moose are actual counted individuals. Fir tree growth is measured by width of the annual ring produced in 0.1mm. When wider rings are produced, trees are assumed to have grown more during the year. See example on board to set up the graph.

Year / 1960 / 1961 / 1962 / 1963 / 1964 / 1965 / 1966 / 1967 / 1968 / 1969
Moose (tens) / 52 / 54 / 56 / 60 / 65 / 75 / 78 / 82 / 100 / 120
Wolves / 18 / 20 / 20 / 22 / 18 / 26 / 30 / 26 / 24 / 16
Fir trees (0.1mm) / 41 / 60 / 50 / 48 / 60 / 50 / 58 / 52 / 56 / 57

Year

/ 1970 / 1971 / 1972 / 1973 / 1974 / 1975 / 1976 / 1977 / 1978 / 1979
Moose (tens) / 120 / 130 / 140 / 135 / 140 / 125 / 122 / 110 / 100 / 105
Wolves / 18 / 20 / 24 / 25 / 30 / 38 / 42 / 30 / 32 / 34
Fir trees (0.1mm) / 50 / 40 / 38 / 37 / 37 / 38 / 39 / 40 / 40 / 41
Year / 1980 / 1981 / 1982 / 1983 / 1984 / 1985 / 1986 / 1987 / 1988 / 1989
Moose (tens) / 90 / 85 / 80 / 100 / 90 / 110 / 112 / 108 / 130 / 160
Wolves / 35 / 34 / 28 / 14 / 20 / 21 / 18 / 16 / 14 / 10
Fir trees (0.1mm) / 56 / 52 / 52 / 38 / 36 / 38 / 34 / 30 / 28 / 26

Name: ______Period: ______

Graphing: Population Growth Curves

Analysis Questions. Be sure to refer to the correct graph when answering the questions.

Yeast population growth

  1. What type of growth curve is shown in the section from zero hours to about ten hours?
  1. What is the approximate carrying capacity (K) of yeast in this situation?
  1. Assuming this yeast is growing in a covered laboratory dish and has limited food resources, what would you predict would happen to the growth curve 8-12 hours after the time you graphed?

Beetle population growth

  1. Does the graph show the population of beetles as r-selected or K-selected? Explain.
  1. What do you predict is the carrying capacity of this beetle population?
Wolves, moose and fir trees
  1. Explain why if wolf numbers are high, the number of moose usually goes on a downward turn and why when moose numbers are increasing the wolf population usually increases shortly after.
  1. During the period from about 1960-1965, moose numbers are fairly low. During this time, the tree growth is high, but varies every year. Since the number of moose is basically steady, what other factors could explain the varied growth of the trees?
  1. In 1988-89 and especially 1983, the populations of moose are high and/or on an increasing pattern, yet the number of wolves decreases dramatically. What do you think could be the cause of this decline in number of wolves when food is abundant?
  1. Sketch a rough graph in the space below (accurate scale is not needed) that would show the pattern of wolf population and tree growth for about ten years following the opening of a hunting season on moose on the island. Be sure to label the graph for clarity.