Chapter 9 - Population Distribution and Regulation Flashcards
Case study: Explain why some islands have kelp forests, and others have urchin barrens?
Urchins, otters, and potentially killer whales set in motion a chain of events influencing marine ecosystems.
- Grazing by sea urchins may prevent the formation of kelp forests.
- Sea Otters as Urchin Predators
- Killer Whales decrease Sea Otter Population
Dominant kelp species in kelp forests
Laminaria and Nereocystis
the geographic area where individuals of the species are present
Distribution
the number of individuals of a species that are found in a given area
Abundance
Trait of populations that state distributions and abundances can change greatly over time and space
Dynamic
A group of individuals of the same species that live within a particular area and interact with one another.
Population
In species that reproduce sexually, a population might be defined as
the group of individuals that interact by interbreeding
In species that reproduce asexually, a population must be defined by
Interactions aside from interbreeding (i.e. competition for food, etc.)
Number of individuals in a population
Population Size
Number of individuals per unit area
Population Density
Abundances change over time and space, why/how
Why: Because the number of individuals in population changes over time
How: Some can migrate to other populations or because of death, birth, etc.
Movement of organisms from one place to another
Dispersal
Significance of Dispersal
- Connects different populations
- Maintains interactions and biodiversity
- Spatial extent of populations vary significantly
Influences the distribution, interaction, and diversity of animal populations.
Essential for spread and survival of plant species
Movement
Results from both abiotic environmental factors and human activities
Patchy Population
- The product of a single fertilization event
- A genetic individual resulting from a single fertilization event
- In organisms that can reproduce asexually, it may consist of multiple, genetically identical parts, each of which has the potential to function independently
Genet
An actually or potentially physiologically independent member of a genet that may compete with other members for
resources.
Ramet
Groups of genetically identical individuals identified by the detachment of clonal offspring from the parent.
Budding
Identification involves recognizing clonal offspring produced from unfertilized eggs or parthenogenesis.
Apomixis
Groups recognized as clonal offspring are produced as the organism grows horizontally
Horizontal spread
Genet and Ramet are appropriate for studying what respectively?
Evolutionary change and Competition among independent organisms
The distribution and abundances of a species are limited by these three factors
Habitat suitability
Historical Factors
Dispersal
Refers to the degree to which an environment provides conditions necessary for a species to thrive.
Habitat Suitability
Key Abiotic factors of the environment with regards to habitat suitability
Climate
Soil pH
Salt concentration
Available nutrients
Key Biotic Features of the Environment with regards to habitat suitability
Dependency on Other Species
Exclusion by Biotic Interactions
Biological Control Considerations
Interactions Between Abiotic and Biotic Features
Temperature Limits
Geographic distribution
Competition
An abiotic event that kills or damages some individuals in an ecosystem creating opportunities for other individuals to grow and reproduce
Disturbance
T/F Earth’s Evolutionary and Geologic History significantly influences current distribution of organisms.
True
Occurs when a species’ limited capacity for dispersal prevents it from reaching suitable habitats
Dispersal Limitation
T/F Dispersal is not influenced by population density.
False, it is
Entire geographic region over which a species is found.
Includes the areas it occupies during all of its life stages.
Geographic Range
Spatial arrangement, of individuals within a population
Dispersion
3 Basic Patterns of Dispersion
- Regular
- Random
- Clumped
Dispersion where individuals are relatively evenly spaced through their habitat
Regular dispersion
Dispersion individuals were positioned at locations selected at random
Random dispersion
Most common distribution, Individuals of a species are unevenly distributed throughout their habitat occurring in clustered group or patches
Clumped Dispersion
The most direct way to determine how many individuals live in a population
Count all of them
Actual abundance
Absolute population size
Number of individuals in one time interval or place relative to the number in another
Relative Population Size
To estimate the population sizes of immobile organisms
Organisms are counted in a series of sample plots, or quadrats, and the resulting numbers are used to estimate the total population size.
Area-Based Counts
Estimates of abundance based on various measurements of distance from a point or line.
Each individual that the observer can see from the line is counted, and its perpendicular distance from the line is recorded.
Distance methods
must be used to convert such distance measurements into an estimate of the absolute population size.
Detection Function
Relies on releasing marked individuals and then recapturing them at a later time to see what fraction of the population is marked.
Mark-Recapture studies
A tool that predicts a species’ geographic distribution based on the environmental conditions at locations the species is known to occupy.
Niche model
