Week 4-5 Flashcards
What is a metapopulation
Many populations of a single species in a region linked by immigrations and emigrations
What is the model for geometric growth for an open population
Nt+1= Nt+ B – D + I - E
What are the dynamics of a metapopulation determined by
by the
rate of colonization of empty patches and extinction of
individual subpopulations
What are the 3 stages of dispersal
emmigration, transfer and immigration
Define dispersal
The movement of individuals away from others
Define migration
the mass directional movement of large numbers of individuals of a species from one location to another
What is natal dispersal
the movement between the location where individuals are born and where it reproduces
What is breeding dispersal
movement between two successive breeding areas
What are the 4 dispersal mechanisms
passive dispersal
passive dispersal by mutualistic agent
active dispersal
clonal dispersal
What is passive dispersal
Non-exploratory, destination is a matter of chance, like dandelion seeds
What is passive dispersal by a mutualistic agent:
animals eating fruit and defecating the seed away from the original tree
what is active dispersal
dispersal controlled by the individual
What is a clonal dispersal
common on modular organisms, an individual branch spreads its parts around as it grows
What is random disperson
when an organism has the tendency to avoid other organisms or when organisms
What is aggregated dispersion
when individuals are attracted to parts of the
environment or by other individuals
Types of seed dispersal
- gravity,
- wind,
- ballistic,
- water and
- by animals
What is density dependent dispersal
Dispersal depends on local population size, availability of resources, habitat quality and habitat size
Example of density dependent dispersal
Large aphid populations have a lower growth rate than small ones as more aphids are dispersing
Example of inverse density dependent dispersal
Grey-tailed voles were found to disperse less when part of a large population than at as small due to males wanting to overlap several female territories
What species use density independent dispersal
All species that use
passive dispersal by wind, gravity or currents (plants,
spiders, some insects, fish)
What are the 3 main evolutionary consequences of dispersal
Inbreeding avoidance
Competition avoidance
Philopatry
Why is inbreeding avoidance important
Because when close related individuals breed they are likely to suffer from inbreeding depression in fitness -favours dispersal
What is philopatry
tendency of an organism to stay in or habitually return to a particular area`
Why is outbreeding depression a force against dispersal
long distance dispersal may bring together genotypes that are adapted to different environments and the resulting offspring may not be adapted to either environment