Niches

Question 1

The Ecological Niche

Answer 1

• The niche of an organism is defined by its needs and tolerances
• Describes the ways in which tolerances and requirements interact to define conditions and resources needed by an individual.
  e.g. nest site, foraging time, food resources, temperature, nutrients, humidity

Question 2

Types of niches

Answer 2

• Fundamental: all the potential resources that a species can use in its environment.
• Requires the absence of competition
• Realized niche – some habitats and resources are not available because competitors occupy them.
• This is what the species actually uses

Question 3

Conditional Differentiation

Answer 3

• Also called temporal niche partitioning
• Species differ in their competitive abilities based on varying environmental conditions
  e.g. thermal niches in ants mean different species forge at different times of the day

Question 4

Niche differentiation and character displacement

Answer 4

• Character displacement is when similar species’ habits overlap and they are in direct competition for food and other vital resources
• Leads to a change in species traits due to niche differentiation or resource partitioning

Question 5

Evolution of character displacement

Answer 5

• 2 sympatric species differ more than 2 allopatric species
  1. sympatric = ranges overlap
  2. allopatric = ranges do not overlap

Question 6

Development of niche differentiation

Answer 6

• Overtime two competing species either co-exist through niche differentiation or compete until one species becomes locally extinct
• Theories for how niche differentiation arises:
  1. Current competition - two co-existing species do not compete bc past competitive interactions lead to niche differentiation and reduce competitive pressure
  2. Past Extinctions - species in the final community are not out-competing each other so the presence if niche differentiation is impossible to detect