Habitat Selection Flashcards
(14 cards)
What is a habitat?
An environmental or ecological area inhabited by a particular species.
What makes an area a habitat?
1) Resources
2) Abiotic factors (appropriate temperature and moisture levels)
3) Levels of predation, parasitism, disease, and competition
4) Appropriate ultimate level factors
Why is average fitness (average reproductive fitness) relatively equal for individuals living in low and high-quality habitats?
This is because of density! After migration, there will be enough individuals who will choose the high-quality habitat, but an individual may choose the low-quality habitat because they will be “better off” than to compete with the individuals in the high-quality habitat.
What is the Ideal Free Distribution Model?
Animals will distribute themselves spatially in ways that maximize reproductive success.
What does the Ideal Free Distribution assume?
1) Habitat locations differ in resources
2) Individuals attempt to maximize fitness (ideal)
3) Individuals are free to move at no cost
4) Animals can accurately assess habitat quality
5) Fitness is negatively density-dependent
6) Individuals are equal competitors
In general, where do animals settle?
Animals are going to settle in the habitat that’s going to give them a higher (maximize) their fitness.
What are the Ideal Free Distribution predictions at equilibrium?
1) Density in each habitat is proportional to habitat quality
2) Individual fitness does not differ between habitats.
Are the assumptions of the IFD model reasonable?
1) Pretty reasonable
2) Pretty reasonable
3) Iffy!
4) Reasonable
5) Iffy!
6) Iffy!
Why is the assumption “Individuals are free to move at no cost” considered iffy in the IFD model?
Any type of movement is going to have a cost (require energy).
In some situations, individuals are NOT free to move. EX: increased predation risk and/or inaccessible.
How do animals assess habitat quality?
- May use environmental cues
- May use conspecific cueing to identify good-quality habitats
What does “conspecific cueing” mean?
If older individuals of your species are in that environment, that’s a signal of a good environment.
Why is the assumption “Fitness is negatively density-dependent” considered iffy in the IFD model?
There are some situations where this doesn’t “hold up.” EX: Allee effect
What is the Allee Effect?
When a population size is low, individual fitness may increase with density (getting benefits by being around their conspecifics).
Why is the assumption “Individuals are equal competitors” considered iffy in the IFD model?
Individuals may exclude others from superior sites!
