Niche Theory Flashcards
What affects species distribution?
Abiotic factors, resource requirements and interspecific interactions.
Define conditions.
Abiotic environmental factors that influence the functioning of living organisms.
What is the long term persistence threshold?
The intrinsic rate of increase (r) must be equal to or exceed 0.
What does an r value equal to or less than 0 indicate?
The conditions only allow for survival or growth and not reproduction.
What are resources and why are they important?
They are something consumed by an organism (eg space or food) and provide the basis for most competition.
What can be said of the niches of 2 species in an area?
The niches cannot be identical.
Niche I theory.
Placed emphasis on conditions - study focussed on the climate of the area (Grinell 1917).
Niche II theory.
Placed emphasis on resources and interactions between species (Elton 1927).
Niche III theory.
Considers both conditions and resources - AKA tolerances and requirements (Hutchinson 1957).
Which concepts were introduced by Hutchinson in 1957?
Fundamental vs realised niche and n-dimensional hypervolume.
What are n-dimensional hypervolumes?
Multiple resources and conditions that limit distribution. Organisms die outside of them.
How does the fundamental niche link to hypervolumes?
It is the complete hypervolume - the full range of conditions/resources in which r exceeds 0.
How does the realised niche link to hypervolumes?
It is the occupied hypervolume in the presence of competitors and predators.
What are the 3 responses to climate change? 1 is not recommended.
Tracking the niche through space (moving).
Adaptation.
Extinction.
What problems are there with species distribution models?
You need to decide which niche to model eg fundamental or realised.
The niche may change over time.
