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Biology LibreTexts

45.1A: Population Demography

  • Page ID
    14183
  • Demography is the study of population dynamics, using statistical and mathematical tools.

    Learning Objectives

    • Explain the importance and function of population demography

    Key Points

    • Demographic studies help scientists understand the population dynamics of species, such as invasive species like the Asian carp.
    • Population fluctuations depend on the weather, food availability, natural disasters such as forest fires or volcanic eruptions, predation, and biological competition.
    • Researchers originally designed demographic tools to study human populations, but demographic approaches can be applied to all living populations.

    Key Terms

    • demography: the study of populations and how they change
    • population dynamics: the variation of populations due to birth and death rates, by immigration and emigration, and concerning topics such as aging populations or population decline
    • statistics: a systematic collection of data on measurements or observations, often related to demographic information such as population counts, incomes, population counts at different ages, etc.

    Introduction

    Imagine someone sailing down a river in a small motorboat on a warm day. She is enjoying the warm sunshine and cool breeze when suddenly a 20-pound silver carp hits her in the head. The presence of Asian carp in U.S. waterways make this risk very real on rivers and canal systems, particularly in Illinois and Missouri.

    image

    Asian carp jump out of the water in response to electrofishing: The Asian carp in the inset photograph were harvested from the Little Calumet River in Illinois in May, 2010, using rotenone, also used as an insecticide.

    The several types of Asian carp include the silver, black, grass, and big head carp. These have been farmed and eaten in China for over 1,000 years; it is among the top aquaculture foods worldwide. In the United States, however, Asian carp is considered to be an invasive species. It disrupts the structure and composition of native fish communities to the point of threatening native aquatic species.

    Biologists are working to understand the biology and ecology of Asian carp. The aim is to develop methods of controlling the species without damaging native fish. Understanding the population dynamics of the carp will help biologists develop and implement measures that reduce its population, allowing scientists to model the statistics of carp populations.

    Population demography

    Populations are dynamic entities, consisting of all of the species living within a specific area. They fluctuate based on a number of factors: seasonal and yearly changes in the environment, natural disasters such as forest fires and volcanic eruptions, and competition for resources between and within species.

    Demography, the statistical study of population dynamics, uses mathematical tools to investigate how populations respond to changes in their biotic and abiotic environments. Researchers originally designed demographic tools, such as life tables, to study human populations. To determine insurance rates, life insurance companies developed methods to analyze life expectancies of individuals in a population. The term “demographics” is often used in discussions of human populations, but demographic approaches can be applied to all living populations.