40 Questions
What is the primary defining characteristic of a population?
Individuals of one species living in a particular area
What is the term for the entire area occupied by a species?
Geographic range
What is the term for species that live in a single, often isolated, location?
Endemic
How is the area of occurrence mapped?
By defining a relevant grid size and mapping only suitable areas
What determines the geographic distribution of a population?
Ecological suitability, geographic barriers, and human impacts and introductions
What is the fundamental niche of a species?
The range of abiotic conditions under which a population/species can persist
What is an example of a species with a limited geographic distribution?
Kangaroo Island dunnart
What is the term for species with very large geographic ranges that can span several continents?
Cosmopolitan
What happens when a population's geographic distribution changes from continuous to fragmented?
The population's range decreases
What is the term for the process of individuals moving from one area to another?
Dispersal
What is the realised niche of a species?
The range of abiotic conditions under which a population of a species actually occurs
What is the primary difference between the fundamental niche and the realised niche?
The fundamental niche is larger than the realised niche
What is the primary purpose of ecological niche modelling?
To identify/predict suitable habitat conditions for a species
What is abundance in ecology?
The total number of individuals in a population that exist within a defined area
What is the primary reason for studying dispersal in ecology?
To understand the ecological importance of dispersal in colonising new areas
What is the primary benefit of dispersal in ecology?
Colonisation of new areas and avoidance of crowding
What type of dispersal occurs when an individual moves from its place of origin to a new location as an adult?
Adult dispersal
What is the primary cost of dispersal in ecology?
Increased exposure to novel conditions and pathogens
What is density in ecology?
The number of individuals per unit of space
What is the primary reason for studying density in ecology?
To understand the ecological importance of density in population growth
What is the primary factor that determines the realised niche of a species?
Interactions with other species
Which of the following is a characteristic of ecological niches?
They are dynamic and can change over time
What is the primary difference between a population's geographic distribution and its geographic range?
Geographic distribution refers to the area occupied by a population, while geographic range refers to the entire species
What is the primary purpose of measuring the density of a population?
To understand how the population may change in the future
What is the main reason why the area of occurrence may include unsuitable areas?
To include areas that are not suitable for the species but are part of the overall range
What is the primary role of ecological suitability in determining the geographic distribution of a population?
It defines the range of abiotic conditions under which a population can persist
What is the primary benefit of natal dispersal?
All of the above
What is the primary consequence of human impacts and introductions on the geographic distribution of a population?
It results in the fragmentation of the population's geographic distribution
Which of the following is a cost of dispersal?
Exposure to novel pathogens and predators
What is the primary difference between a continuous distribution and a fragmented distribution?
A continuous distribution is characterized by a single, unbroken area of occurrence, while a fragmented distribution is characterized by multiple, isolated areas of occurrence
What is the primary difference between active and passive dispersal?
The decision-making process of the organism
What is the primary reason for studying ecological niche modelling?
To predict the distribution of a species under future climate scenarios
What is the primary reason why the geographic distribution of a species may be limited to a single, isolated location?
The species is found in a location with a unique set of abiotic conditions
What is the primary role of geographic barriers in determining the geographic distribution of a population?
They provide a physical barrier to the population's expansion
Which of the following is a characteristic of human-originated populations?
They are often evenly spaced
What is the primary reason for studying abundance in ecology?
To identify potential problems, such as declines or increases
What is the primary reason why a population's geographic distribution may change over time?
The population is experiencing human impacts and introductions
What is the primary factor that determines the density of a population?
All of the above
What is the primary benefit of mapping a population's geographic distribution?
It allows for the identification of areas with high conservation value
What is the primary challenge in defining a population's geographic distribution?
Defining the boundaries of the population's range
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.
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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