Ecology Lecture 11
What happens with migration (i.e., open populations)?
(Open) Population Growth
Population growth rates (dN/dt) determined by:
R = b – d + i – e
Migration occurs via dispersal. Dispersal to an unoccupied habitat patch is referred to as
Circled population – good indication of immigration because when the subpopulation
size gets to zero (goes extinct/extirpated), recruitment occurs via immigration (this
subpopulation was rescued by another subpopulation)
- A collection of spatially distinct subpopulations (or patches) of the same species that are
connected to one another via dispersal. Also referred to as a “population of populations”.
- Strictly, the whole system persists over time, even though individual populations
sometimes go extinct. - Becoming more common with fragmentation – at one time very large populations, get
chipped away & become a collection of smaller populations.
- The movement of an organism from its place of birth or activity to another location. It
usually refers to the movement of individuals or propagules (larvae/seeds/spores) of
fragments away from a group of others of the same species.
- Dispersal facilitates the search of new resources (food, space, mates), reduces
competition, & allows colonization of new areas to increase a species’ range.
- Endozooic: ingested by one organism and passed through the digestive system
- Epizootic: attach to an organism & transfer with it
Biotic/Abiotic mechanisms with large dispersal or any mechanism with large
dispersal: best for a metapopulation
- Arrows indicate dispersal/movement, blobs are patches
- (patch that says occupied refers to the one below it)
Whole concept of the metapolution.
Criteria for Metapopulation
Necessary conditions for metapopulation to be applicable to a system of local
populations: 1) Suitable habitat occurs in discrete patches that may may be occupied by local breeding
2) Even the largest populations have a substantial risk of extinction (may include: core
3) Habitat patches must not be too isolated to prevent