L9 - Dispersal Flashcards
What is odd about lemmings migration?
Mass suicide
What controls lemming populations?
Predator aggregation (all predators switch focus to hunting lemmings)
What is dispersal?
When an animal/ group of animals move to a new location and do not return - permanent change of place
What is carrying capacity?
The number of people, animals, or crops which a region can support without environmental degradation
What are the costs of dispersal?
- Energetic costs
- Investment in dispersal physiology
- Predation
- Failure to find new habitat
What is demographic stochasticity?
The random fluctuations in population size that occur because of randomness in the population
How can temporal variability favour dispersal?
If there are small populations in different places and one of the populations goes extinct, there is now a new habitat for some of other populations to go to
Give an example of when a new invasion selects for dispersal
The introduction of the cane toad in Australia
Which part of cane toad anatomy changed during their invasion of Australia?
The legs got longer
Give an example of when dispersal can be favoured if animals can anticipate their environments
Spodoptera frugiperda (fall armyworm/ moth):
- If worm eat their siblings they grow in to smaller moths with the same size wings, leads to being better dispersers
What is the main factor that favours dispersal?
Environment inconstancy
What is inbreeding depression?
The reduced biological fitness that has the potential to result from inbreeding
What is anisogamy?
A form of sexual reproduction that involves the union or fusion of two gametes that differ in size and/or form
How can anisogamy favour sex-dependent dispersal?
For males it is advantageous to disperse as will find new unrelated mates
For females it is not advantageous as will have to raise young in unfamiliar environment and innately already able to pick unrelated mates
How can inbreeding depression favour dispersal?
To find new unrelated mates
