POPULATION ECOLOGY
Population Interactions - Research Connections

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TABLE OF CONTENTS
2. Competition (PDF 343 KB)
  • Research Connection 1: Interspecific competition in a Chihuahuan desert rodent community through direct and indirect effects.
  • 3. Predation (PDF 362 KB)
  • Research Connection 2: The impact of food abundance and predation by Canada lynx on the 10-year snowshoe hare cycle through both direct and indirect effects.
  • 4. Mutualism (PDF 217 KB)
  • Research Connection 3: The costs and benefits associated with the mutualistic interaction between yuccas and yucca moths.
  • 5. Guilds (PDF 619 KB)
  • Research Connection 4: Interspecific competition within a guild of African Acacia-ants.



  • 1. INTRODUCTION TO POPULATION INTERACTIONS Print Version

  • Ecologists classify population interactions with regards to their outcomes (Table 1).

    Table 1. A classification of population interactions and outcomes.
    SPECIES A
    SPECIES B
    Positive (+)
    Neutral (…)
    Negative (-)
    Positive (+)
    Mutualism
    -
    -
    Neutral (…)
    Commensalism
    Neutralism
    -
    Negative (-)
    Predation
    Amensalism
    Competition


  • The outcome of the interaction between a flowering plant and its butterfly pollinator is quite different than the outcome of the interaction between a cat and juvenile robin. In the first example, both butterfly and plant benefit: one by getting a nectar meal and the other by cross-fertilization of its flowers. In the second example, only the cat benefits by making a meal of the robin.

  • When two species use the same resource at the same time, the result is Competition and neither species does as well as it would in the absence of the other species. Predation is an interaction in which one species feeds on another species to that second species' detriment. Mutualism benefits both species. Research connections and examples are provided for competition, predation and mutualism in the next section.

  • Commensalism is when a species benefits by living in or on another species but has no effect on its host. Amensalism is an interaction in which one species is detrimentally affected, while the species it interacts with is not affected at all. Neutralism is where neither species is affected by their interaction.

  • An understanding of how populations interact is important for Conservation and Management because this information can be used to:

    1) Monitor changes in biological community structure.
    2) Understand how human activities that affect one species may also have indirect effects on other species.
    3) Determine the impacts of invasive or introduced species on populations.

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    6. RESEARCH LITERATURE CONNECTION Print Version


    Addicott, J.F. 1998. Regulation of mutualism between yuccas and yucca moths: population level processes. OIKOS 81: 119-129.

    Addicott, J.F., and T. Boa. 1999. Limiting the costs of mutualism: multiple modes of interaction between yuccas and yucca moths. Proceedings of the Royal Society of London, Series B 266: 197-202.

    Begon, M., Mortimer, M. and Thompson, D.J. 1996. Population Ecology: A Unified Study of Animals and Plants. 3rd ed. Blackwell Science Ltd. Oxford, U.K. 247 pp.

    Brown, J.H. 1975. Geographical ecology of desert rodents. Pp. 315-341. In Cody, M.L. and Diamond, J.M. (Ed.) Ecology and Evolution of Communities. The Belknap Press of Harvard University Press. Cambridge, MA. 545 pp.

    Faaborg, J. 1988. Ornithology: An Ecological Approach. Prentice-Hall, Inc., Eaglewood Cliffs, NJ. 470 pp.

    Heske, E.J., J.H. Brown, and S. Mistry. 1994. Long-term experimental study of a Chihuahuan desert rodent community: 13 years of competition. Ecology 75(2): 438-445.

    Krebs, C.J., R. Boonstra, S. Boutin, and A.R.E. Sinclair. 2001. What drives the 10-year cycle of snowshoe hares? Bioscience 51(1): 25-35.

    Krebs, C.J., S. Boutin, R. Boonstra, A.R.E. Sinclair, J.N.M. Smith, M.R.T. Dale, K. Martin, and R. Turkington. 1995. Impact of food and predation on the snowshoe hare cycle. Science 269(5227): 1112-1115.

    MacLulick, D.A. 1937. Fluctuation in the numbers of varying hare (Lepus americanus). University of Toronto, Department of Biology Series 43: 1-136.

    Root, R.B. 1967. The niche exploitation pattern of the blue-gray gnatcatcher. Ecological Monographs 37(4): 317-350.

    Stanton, M.L., T.M. Palmer, and T.P. Young. 2002. Competition-colonization trade-offs in a guild of African acacia-ants. Ecological Monographs 72(3): 347-363.

    Temple, S.A. 1979. The Dodo and the Tambalacoque Tree. Science 203: 1363-1364.

     
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