Lecture 14: Disturbance and Abundance Flashcards
Define population
A group of individuals from the same species that occur at the same time and space.
What are some characteristics of a population?
Density: number of individuals per unit area
Distribution: size, shape, and location
Population: Define absolute density and ecological density
Absolute density: number of individuals per unit area (number of moose per hectare)
Ecological density: number of individuals per unit area of suitable habitat (number of moose per hectare of forest)
Define metapopulation
A group of subpopulations that live on spatially isolated patches which are connected by exchanging individuals
What are the characteristics for a metapopulation?
- They are a population of subpopulations
- They are connected by the movement of from one subpopulation to another
- They can go extinct and be re-colonized repeatedly at any point in time
- Extinction is greater in smaller subpopulations of smaller areas
- Presence of density-dependent and density-independent population dynamics
What influences population distribution and abundance?
Habitat suitability - abiotic and biotic factors, historical factors, and dispersal limitation.
Define dispersal limitation and give an example
When a species is unable to reach its suitable habitat due to limited capacity.
Example: A polar bear is unable to live in Antartica since it has to disperse through tropical regions. As well as Antarctic species are not adapted to coexist with polar bears.
Define dispersal
The permanent movement of individuals from one population to another.
Define migration
The seasonal movement of individuals from one location to another.
Why is dispersal important?
Dispersal prevents inbreeding when juveniles undergo natal dispersal.
What are some sex-based patterns of natal dispersal?
Female birds are more likely to undergo natal dispersal because males are territorial and will protect their territories for years.
Male mammals are more likely to undergo natal dispersal to avoid breeding with related females since they’re a polygynous species.
What are some methods of seed dispersal?
Other animals, water, gravity, explosion, and wind.
What are the two major categories of dispersal?
Immigration: movement into a population
Emigration: movement out of a population
What responses do predators show in variation to prey density?
Functional response: changes in feeding rate
Numerical response: changes in density of both populations
What drives numerical responses? And how does that affect predator and prey populations?
Reproduction: peak of prey and predator populations are not synchronized with a time-lag due to predators needing more time to reproduce.
Dispersal: peak of prey and predator populations are synchronized with no time-lag due to high mobility and tracking.
