Ch. 16: Competition Flashcards
Competition is a…
(–)/(–) interaction when individuals use the same limited resources
Resource
anything an organism consumes or uses that causes an increase in population growth rate when it becomes more available
- must be consumable
resources for animals include:
food, water, space
resources for plants include:
sunlight, water, and soil nutrients
T/F: temperature is considered a resource
FALSE
- any ecological factors that cannot be consumed are NOT considered resources
Liebig’s law of the minimum
law stating that a population increases until the supply of the most limiting resource prevents it from increasing further
- not all resources limit consumer populations.
When two species compete for a single limiting resource, the species that persists is the one that can…
drive down the abundance of that resource to the lowest level
An increase in one resource can have a much larger effect on a population when there is also an…
increase in a second resource
Intraspecific competition occurs between…
members of the SAME species
Negative density dependence is a common type of __________, where an increase in a population’s density causes a decline in the growth rate of the population.
intraspecific competition
Interspecific competition occurs between…
members of two DIFFERENT species
Interspecific competition occurs when…
the niches of two species overlap
- you can’t have 2 species occupy the same niche, they will move a little away so they don’t have to compete
habitat
place/set of environmental conditions where particular organism lives
ecological niche
- role species plays in biological community
- total set of environmental factors species can tolerate
- ex: autotroph (producers, herbivores), heterotrophs (consumers)
generalists
occupy a broad niche
specialists
occupy a narrow niche
when generalists and specialists collide _____ usually win
generalists
Species interactions may affect ___ and ___ of a particular species.
the distribution and abundance
Interspecific competition can cause the population of one species to…
decline and eventually die out
competitive exclusion principle:
it is not possible for species within the same niche to coexist
- one will “win” out and other will move or die off
Law of Competitive Exclusion:
- No 2 species will occupy the same niche and compete for exactly the same resources for an extended period of time.
- 1 will either migrate, become extinct, or partition the resource and utilize a sub-set of the same resource.
competitive exclusion occurs when…
competition is asymmetric and niches overlap completely
the consequences of competition (“niche differentiation”)
- weaker species will retreat to an area of non-overlap
Darwin suggested that competition is most intense between….
related species because they have similar traits and consume similar resources.
For related species that compete strongly, natural selection should favor…
differences in habitat use
if niches don’t overlap completely, weaker competitors use….
non-overlapping resources
Competition can also be intense among…
distantly related species that consume a common resource
Competition can also be intense among…
distantly related species that consume a common resource
Population dynamics of two competing species can be modeled by using ______
the logistic growth equation
Zero population growth isocline:
population sizes at which a population experiences zero growth
Two species may be able to coexist when…
each is better at persisting at low levels of DIFFERENT resources
- they’re all relying on multiple, slightly different resources
The outcome of competition can be altered by…
abiotic conditions, disturbances, and interactions with other species
the most competitive organisms are often the most….
susceptible to predation or herbivory
Predators can reverse…
the outcome of competition
Herbivores can alter…
the outcome of competition
Types of competition
- consumptive competition
- preemptive competition
- overgrowth competition
- chemical competition
- territorial competition
- encounter competition
- apparent competition
Consumptive competition (Exploitative competition):
- competition in which individuals consume and decrease the abundance of a resource to a point that other individuals cannot persist
consumptive (exploitative) competition is considered ____ competition because it occurs through ____.
- indirect
- a shared resource.
preemptive competition
competition for space (and access to resources)
overgrowth competition
one organism grows over another
Interference competition:
when competitors do not immediately consume resources but defend them
- direct competition
4 types of interference competition
chemical, territorial, encounter, apparent
Allelopathy (chemical interference)
type of interference competition when organisms use chemicals to harm their competitors
- effective strategy for invasive plants
territorial competition
mobile organisms protect a feeding or breeding territory
aggressive interactions are a type of..
interference competition
encounter competition
organisms interfere directly for access to specific resources
apparent competition
form of competition b/w species indirectly competing with another species (or group of organisms)
- both of them serve as prey, parasite or herbivore
apparent competition occurs when…
the first group of species increases in number
- this results in the increase in number of predators in the area
- increase in number of predators (all different types of predators trying to eat 1 type of prey)
_____ competition could be generated if one species facilitates the enemy of another species.
Apparent
organisms are able to use a combination of…
competition and competition types
Chi-square test
a statistical test that determines whether the number of observed events in different categories differs from an expected number of events, based on a particular hypothesis; useful when data are counts
