52 Community Ecology Flashcards
What are the four most common types of interactions among species?
Commensalism, competition, consumption, mutualism
Commensalism
species relationship where one organism (the commensal) benefits and the other (the host) is unaffected
Competition
interaction of 2 species or 2 individuals trying to use the same limited resource (e.g. water, food, living space), resulting in lower fitness for both; may occur between individuals of the same species (intraspecific) or different species (interspecific)
Consumption
interaction between species where one organism eats or absorbs nutrients from another (e.g. predation, herbivory, parasitism), increasing the consumer’s fitness but decreasing the victim’s fitness
Mutualism
species relationship between 2 organisms (mutualists) that benefits both
3 key themes of species interactions
(1) Species interactions can affect the distribution and abundance of a particular species (2) Species act as agents of natural selection when they interact (3) The outcome of interactions among species is dynamic and conditional
Coevolution
A pattern of evolution in which 2 interacting species reciprocally influence each other’s adaptations over time
Intraspecific competition
competition between members of the same species for the same limited resource; intensifies as population density increases
Interspecific competition
competition between members of different species for the same limited resource
Niche
the range of resources that a species can use and the range of conditions that it can tolerate; the role a species plays in its ecosystem
Symmetric competition
ecological competition between 2 species in which both suffer similar declines in fitness; when the niches of 2 species overlap
Asymmetric competition
ecological competition between two species in which one species suffers a greater fitness decline than the other depending on the amount of overlap in their niches
Competitive exclusion principle
two species cannot coexist in the same ecological niche in the same area because one species will outcompete the other
Fundamental niche
total theoretical range of environmental conditions that a species can tolerate
Realized niche
portion of the fundamental niche that a species actually occupies given limiting factors such as competition with other species
Niche differentiation or resource partitioning
evolutionary change in resource use by competing species that occurs as the result of character displacement
Character displacement
evolutionary tendency for the traits of similar species that occupy overlapping ranges to change in a way that reduces interspecific competition
Community
all of the populations that interact with one another in a given area
Ecological disturbance
any event that removes significant biomass from a community; impact depends on 3 factors: type, frequency, severity
Ecological succession
development of a community after a disturbance
Primary succession
occurs after a disturbance removes all the biomass and all the soil from an area e.g. volcanic eruptions, glaciers, floods, landslides
Secondary succession
occurs after a disturbance removes some or all biomass from an area, but leaves the soil intact e.g. forest fires, logging, construction, farming
Pioneer species
high dispersal, weedy/fast growing, short generations, tolerant of harsh conditions; likely to exponential growth but may never reach its carrying capacity
Climax species
low dispersal, good competitors, long-lived, require favourable conditions; likely to exhibit logistic growth
