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3.1: Population Ecology

  • Page ID
    175751
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    Population Ecology

    Populations are interacting and potentially interbreeding groups of individuals from the same species living in a common area. The study of population ecology focuses on population size and the factors that regulate population growth.

    Wildlife Corridors

     

    Roadkill is a familiar reminder of one of the unintended consequences of our extensive road networks. Roads, especially freeways and highways, not only increase wildlife mortality but also divide habitats into smaller, isolated patches. This habitat fragmentation can make it more difficult for animals to find food, shelter, and mates. Over time, fragmented habitats can reduce biodiversity, limit gene flow between populations, and increase the risk of local extinctions.

     

    To address this problem, ecologists and conservation planners have developed wildlife crossings, such as overpasses and underpasses, and wildlife corridors, which help reconnect fragmented habitats and allow animals to move more safely across landscapes.

    Wildlife overpass over Singapore highway
    Figure \(\PageIndex{a}\): A newly constructed wildlife overpass over a Singapore highway. Image by Benjamin P. Y-H. Lee(opens in new window) (licensed under CC-BY-4.0(opens in new window))

     

     

    • 3.1.1: Ecological Hierarchy
      This page is a summary of the hierarchy in nature.
    • 3.1.2: Population Distribution
      This page discusses the distribution patterns of populations, which include clumped, random, and uniform arrangements. Clumped distribution arises from uneven resource availability or social behaviors (e.g., elephants), random distribution lacks a specific pattern (e.g., dandelions), and uniform distribution occurs with even spacing due to resource scarcity or competition (e.g., saguaro cacti, penguins). These patterns enhance understanding of population interactions beyond just density.
    • 3.1.3: Population Size
      This page discusses the dynamics of populations influenced by factors such as environmental changes and resource competition. It highlights key characteristics like size and density, which affect genetic variation, adaptation, and interactions. The page also covers population size estimation methods, including quadrats for immobile organisms and mark-and-recapture for mobile species, noting that while these techniques yield estimates, actual numbers may be subject to errors and biases.
    • 3.1.4: Population Growth and Regulation
      This page covers population dynamics through models like exponential and logistic growth. Exponential growth is unrestricted (J-shaped curve), while logistic growth considers resource limits (S-shaped curve). It explains that population growth rates (r) hinge on birth and death rates. Additionally, the page discusses factors regulating growth, distinguishing between density-dependent (e.g., predation) and density-independent (e.g., natural disasters) influences.
    • 3.1.5: Life History
      This page explores life tables, which illustrate life expectancy and mortality rates by dividing populations into age groups. It highlights examples, like Dall mountain sheep, to show varying death rates at different ages and categorizes survivorship curves into Types I, II, and III. Furthermore, it contrasts r-selected species, which produce many offspring with minimal care, with K-selected species, which have fewer offspring but provide significant parental investment.

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    Attribution

    This page was heavily revised and rewritten by Erin Rempala and contains adapted content originally authored by Melissa Ha and Rachel Schleiger is licensed CC BY-NC-SA 4.0.

    Rachel Schleiger and Melissa Ha (CC-BY-NC(opens in new window))


    This page titled 3.1: Population Ecology is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Melissa Ha and Rachel Schleiger (ASCCC Open Educational Resources Initiative) .

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