Unit II: Community Ecology Flashcards
There is a general ______ correlation between niche overlap and competition intensity
positive (*on a graph, it is a positive slope)
What is Niche?
range of resources used and conditions tolerated
What is Fundamental Niche?
theoretical range of environment conditions that a species can tolerate (max & min)
What is Realized Niche?
portion of the fundamental niche that is actually occupied/the resources actually used in nature (given limiting factors)
Can the Realized Niche be bigger than the Fundamental Niche?
No, the realized niche is small because it’s in competition with other species in nature
What happens when two species in a community have overlapping niches?
This will only happen if species are equal.
1. Competitive Exclusion Principle
2. Niche Differentiation
3. Resource Partitioning
What is Competitive Exclusion Principle?
no 2 species within a habitat can coexist when they compete for the same resources at the same place and time
- one species outcompetes the other (asymmetric competition)
- local extinction of weaker competitor
In competition exclusion, the fitness is ____ where the two species’s fundamental niche overlap
low, only the superior species can get the niche overlapping in fundamental niche because natural selection selects against individuals that compete
What is Resources Partitioning?
change in resource use caused by competition over generations
What is Niche Differentiation?
when 2 species separate out of the niche space in which they overlap
What is Character Displacement?
evolutionary changes in traits that make niche differentiation possible (e.g. change in body size)
When does character displacement occur?
happens when species are sympatric with a competitor, therefore the species will have different body types because they’re in competition
What is Sympatric?
overlapping in an area
What is Allopatric?
in separate areas (geographically)
When species are allopatric, this means they are not in ________, and the species will have very similar body sizes.
competition
What is Mimicry?
when one species resembles another
What is Bayesian Mimicry?
when a harmless/patable species mimics a dangerous/unpalatable species
Who is the Bayesian Mimicry names after?
Henry Walter Bates (Wallace’s companion in Brazil)
What is Müllerian Mimicry?
2 or more harmful species mimic each other
Who discovered müllerian mimicry?
Fritz Müller
What is Emsleyan (Mertensian) Mimicry?
type of mimicry where a harmful (deadly) species resembles a less harmful one
How do predators protect the Emsleyan/Mertensian Mimicry?
predators develop learned avoidance of the less harmful model, in order to protect the deadly mimic
What is Aggressive Mimicry?
when a predator mimics a desirable species (e.g. venus fly trap-pretty flower)
What is a Foundation Species?
species which often forms the major structural portion of the habitat; usually the primary producers (e.g. coral reefs)
What is Succession?
sequence of changes in communities occupying an area after an environmental disturbance or the creation of a new substrate
At what stage of succession, do species alter the environment?
each stage, in which a new species in introduced or changes (e.g. as a new tree grows in, less sunlight becomes available)
Succession is impossible to predict. True of False?
False, the changes of succession are often predictable
What are the 3 ways an existing species may affect the species which follows them in introduction?
- Facilitation: conditions become favorable
- Tolerance: no effect
- Inhibitation: hinders establishment
What is Climax Community?
the final stage of succession, where a stable community is formed by a characteristic assortment of plant and animal species; species are tolerant of competition with each other
What are the 2 types of Succession?
- Primary Succession
- Secondary Succession
What is Primary Succession?
succession on land that previously had no life
What is Secondary Succession?
succession in response to environmental disturbances that move a community away from its equilibrium
What is a Pioneer Species?
1st species to appear in primary and secondary succession
What are characteristic of a pioneer species?
- “weedy”
- high rmax
- devote more energy to reproduction than competitive ability
