Characteristics of Populations in Ecology
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Questions and Answers

What is the primary defining characteristic of a population?

  • Individuals of one species living in a particular area (correct)
  • A group of individuals that have the potential to reproduce
  • A group of individuals from different species
  • A group of individuals from the same species that interact with each other

    • What is the term for the entire area occupied by a species?

  • Geographic distribution
  • Area of occurrence
  • Dispersal range
  • Geographic range (correct)

    • What is the term for species that live in a single, often isolated, location?

  • Fragmented
  • Endemic (correct)
  • Disjunct
  • Cosmopolitan

    • How is the area of occurrence mapped?

    <p>By defining a relevant grid size and mapping only suitable areas</p> Signup and view all the answers

    What determines the geographic distribution of a population?

    <p>Ecological suitability, geographic barriers, and human impacts and introductions</p> Signup and view all the answers

    What is the fundamental niche of a species?

    <p>The range of abiotic conditions under which a population/species can persist</p> Signup and view all the answers

    What is an example of a species with a limited geographic distribution?

    <p>Kangaroo Island dunnart</p> Signup and view all the answers

    What is the term for species with very large geographic ranges that can span several continents?

    <p>Cosmopolitan</p> Signup and view all the answers

    What happens when a population's geographic distribution changes from continuous to fragmented?

    <p>The population's range decreases</p> Signup and view all the answers

    What is the term for the process of individuals moving from one area to another?

    <p>Dispersal</p> Signup and view all the answers

    What is the realised niche of a species?

    <p>The range of abiotic conditions under which a population of a species actually occurs</p> Signup and view all the answers

    What is the primary difference between the fundamental niche and the realised niche?

    <p>The fundamental niche is larger than the realised niche</p> Signup and view all the answers

    What is the primary purpose of ecological niche modelling?

    <p>To identify/predict suitable habitat conditions for a species</p> Signup and view all the answers

    What is abundance in ecology?

    <p>The total number of individuals in a population that exist within a defined area</p> Signup and view all the answers

    What is the primary reason for studying dispersal in ecology?

    <p>To understand the ecological importance of dispersal in colonising new areas</p> Signup and view all the answers

    What is the primary benefit of dispersal in ecology?

    <p>Colonisation of new areas and avoidance of crowding</p> Signup and view all the answers

    What type of dispersal occurs when an individual moves from its place of origin to a new location as an adult?

    <p>Adult dispersal</p> Signup and view all the answers

    What is the primary cost of dispersal in ecology?

    <p>Increased exposure to novel conditions and pathogens</p> Signup and view all the answers

    What is density in ecology?

    <p>The number of individuals per unit of space</p> Signup and view all the answers

    What is the primary reason for studying density in ecology?

    <p>To understand the ecological importance of density in population growth</p> Signup and view all the answers

    What is the primary factor that determines the realised niche of a species?

    <p>Interactions with other species</p> Signup and view all the answers

    Which of the following is a characteristic of ecological niches?

    <p>They are dynamic and can change over time</p> Signup and view all the answers

    What is the primary difference between a population's geographic distribution and its geographic range?

    <p>Geographic distribution refers to the area occupied by a population, while geographic range refers to the entire species</p> Signup and view all the answers

    What is the primary purpose of measuring the density of a population?

    <p>To understand how the population may change in the future</p> Signup and view all the answers

    What is the main reason why the area of occurrence may include unsuitable areas?

    <p>To include areas that are not suitable for the species but are part of the overall range</p> Signup and view all the answers

    What is the primary role of ecological suitability in determining the geographic distribution of a population?

    <p>It defines the range of abiotic conditions under which a population can persist</p> Signup and view all the answers

    What is the primary benefit of natal dispersal?

    <p>All of the above</p> Signup and view all the answers

    What is the primary consequence of human impacts and introductions on the geographic distribution of a population?

    <p>It results in the fragmentation of the population's geographic distribution</p> Signup and view all the answers

    Which of the following is a cost of dispersal?

    <p>Exposure to novel pathogens and predators</p> Signup and view all the answers

    What is the primary difference between a continuous distribution and a fragmented distribution?

    <p>A continuous distribution is characterized by a single, unbroken area of occurrence, while a fragmented distribution is characterized by multiple, isolated areas of occurrence</p> Signup and view all the answers

    What is the primary difference between active and passive dispersal?

    <p>The decision-making process of the organism</p> Signup and view all the answers

    What is the primary reason for studying ecological niche modelling?

    <p>To predict the distribution of a species under future climate scenarios</p> Signup and view all the answers

    What is the primary reason why the geographic distribution of a species may be limited to a single, isolated location?

    <p>The species is found in a location with a unique set of abiotic conditions</p> Signup and view all the answers

    What is the primary role of geographic barriers in determining the geographic distribution of a population?

    <p>They provide a physical barrier to the population's expansion</p> Signup and view all the answers

    Which of the following is a characteristic of human-originated populations?

    <p>They are often evenly spaced</p> Signup and view all the answers

    What is the primary reason for studying abundance in ecology?

    <p>To identify potential problems, such as declines or increases</p> Signup and view all the answers

    What is the primary reason why a population's geographic distribution may change over time?

    <p>The population is experiencing human impacts and introductions</p> Signup and view all the answers

    What is the primary factor that determines the density of a population?

    <p>All of the above</p> Signup and view all the answers

    What is the primary benefit of mapping a population's geographic distribution?

    <p>It allows for the identification of areas with high conservation value</p> Signup and view all the answers

    What is the primary challenge in defining a population's geographic distribution?

    <p>Defining the boundaries of the population's range</p> Signup and view all the answers

    Study Notes

    Populations

    • A population consists of individuals of one species living in a particular area, ideally defined by the area occupied by individuals that can reproduce and interact with each other.
    • The area can also be defined by the researcher or project.

    Characteristics of Populations

    • Geographic distribution: the area occupied by the population.
    • Abundance: the total number of individuals in a population within a defined area.
    • Density: the number of individuals per space unit.
    • Dispersion: the spacing of individuals with respect to one another within the distribution.
    • Dispersal: the movement of individuals from one area to another without unlikely return.

    Geographic Distribution

    • Geographic range is commonly applied to the entire species.
    • Endemic species live in a single, often isolated, location.
    • Cosmopolitan species have very large geographic ranges that can span several continents.
    • Distributions can be continuous or fragmented.

    Mapping a Distribution

    • Collect locality data: sites where the population/species occurs.
    • Map extent of occurrence: a polygon encompassing all known localities.
    • Map area of occurrence: define a relevant grid size and map only suitable areas.

    Determinants of Geographic Distribution

    • Ecological suitability: environmental conditions like climate, soil, species interactions.
    • Geographic barriers.
    • Human impacts and introductions.

    Ecological Niche

    • Fundamental niche: the range of abiotic conditions under which a population/species can persist.
    • Realised niche: the range of abiotic conditions under which populations of a species actually occur.
    • Fundamental niche >= realised niche.

    Defining and Measuring Niche

    • Realised niche: measure abiotic conditions of known localities.
    • Fundamental niche: generally unknown, and dynamic due to evolution and adaptation over time.

    Ecological Niche Modelling

    • Statistical methods to identify/predict suitable habitat conditions.
    • Data needed: known locations of the species/population, abiotic characteristics for those locations.
    • Models can predict where the species may be: future climate scenarios, invasive species expansion.

    Abundance

    • The total number of individuals in a population within a defined area.
    • Changes in abundance indicate potential problems: declines may lead to extinction, loss of ecological function, increases may lead to out-competition, range expansion.

    Density

    • The number of individuals per space unit.
    • Higher densities are found in the most ecologically suitable habitats.
    • Densities vary greatly among organisms.

    Dispersion

    • The spacing of individuals with respect to one another within the distribution: clustered, even, uniform or regular, random.
    • Human-originated populations can be very evenly spaced.

    Dispersal

    • The movement of individuals from one area to another without unlikely return.
    • Types: active, passive, natal, adult.
    • Dispersal benefits: colonise new areas, avoid crowding, avoid inbreeding.
    • Dispersal costs: exposure to novel conditions, mortality, energy investment.

    Populations

    • A population consists of individuals of one species living in a particular area, ideally defined by the area occupied by individuals that can reproduce and interact with each other.
    • The area can also be defined by the researcher or project.

    Characteristics of Populations

    • Geographic distribution: the area occupied by the population.
    • Abundance: the total number of individuals in a population within a defined area.
    • Density: the number of individuals per space unit.
    • Dispersion: the spacing of individuals with respect to one another within the distribution.
    • Dispersal: the movement of individuals from one area to another without unlikely return.

    Geographic Distribution

    • Geographic range is commonly applied to the entire species.
    • Endemic species live in a single, often isolated, location.
    • Cosmopolitan species have very large geographic ranges that can span several continents.
    • Distributions can be continuous or fragmented.

    Mapping a Distribution

    • Collect locality data: sites where the population/species occurs.
    • Map extent of occurrence: a polygon encompassing all known localities.
    • Map area of occurrence: define a relevant grid size and map only suitable areas.

    Determinants of Geographic Distribution

    • Ecological suitability: environmental conditions like climate, soil, species interactions.
    • Geographic barriers.
    • Human impacts and introductions.

    Ecological Niche

    • Fundamental niche: the range of abiotic conditions under which a population/species can persist.
    • Realised niche: the range of abiotic conditions under which populations of a species actually occur.
    • Fundamental niche >= realised niche.

    Defining and Measuring Niche

    • Realised niche: measure abiotic conditions of known localities.
    • Fundamental niche: generally unknown, and dynamic due to evolution and adaptation over time.

    Ecological Niche Modelling

    • Statistical methods to identify/predict suitable habitat conditions.
    • Data needed: known locations of the species/population, abiotic characteristics for those locations.
    • Models can predict where the species may be: future climate scenarios, invasive species expansion.

    Abundance

    • The total number of individuals in a population within a defined area.
    • Changes in abundance indicate potential problems: declines may lead to extinction, loss of ecological function, increases may lead to out-competition, range expansion.

    Density

    • The number of individuals per space unit.
    • Higher densities are found in the most ecologically suitable habitats.
    • Densities vary greatly among organisms.

    Dispersion

    • The spacing of individuals with respect to one another within the distribution: clustered, even, uniform or regular, random.
    • Human-originated populations can be very evenly spaced.

    Dispersal

    • The movement of individuals from one area to another without unlikely return.
    • Types: active, passive, natal, adult.
    • Dispersal benefits: colonise new areas, avoid crowding, avoid inbreeding.
    • Dispersal costs: exposure to novel conditions, mortality, energy investment.

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    Description

    Learn about the key characteristics of populations in ecology, including geographic distribution, abundance, density, and more. Understand how these factors define and affect population dynamics.

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