COMMUNITY ECOLOGY Flashcards
What is community ecology?
Community ecology studies the interactions between populations and how community structure is affected by different factors (e.g. disease, predation)
What is a niche?
A niche is the tole of an organism in their environment, or the total of a species’ use of biotic and abiotic resources
What are interspecific interactions?
Interspecific interactions are the relationships between species in a community
What are examples of interspecific interactions?
- Competition
- Predation
- Herbivory
- Symbiosis (parasitism, mutualism, commensalism)
What is competition?
Competition (-/-) is when 2+ species compete for a resource that is in short supply
What is competetive exclusion?
Competetive exclusion is the local elimination of a competing species, where 2 species competing for the same limiting resource cannot coexist in the same niche
Under what conditions can ecologically similar species coexist in a community?
Where there is 1+ significant differences in their niches
What is a realized niche?
A realized niche is the niche an organism can only inhabit due to competition
What is a fundamental niche?
A fundamental niche is the niche an organism can typically inhabit when a competitor isn’t present
What is resource partitioning?
Resource partitioning is an alternative outcome to competition in which the niche of what would otherwide be competing species are differentiated in a way that direct competition is avoided (e.g. temporal, spacial), enabling 2 similar species to coexist in a communtiy
What is predation?
Predation (+/-) is when 1 species, the predator, kills and each the other, the prey
What is aposematic coloration?
Aposematic coloration warns predators to stay away
What is herbivory?
Herbivory (+/-) is when an herbivore eats part of a plant or algae
What is symbiosis?
Symbiosis occurs when individuals of 2+ species live in close contact with one another
What is parasitism?
Parasitism (+/-) is a type of symbiosis where the parasite derives its nourishment from a secondary organism, its host, which is harmed
What is mutualism?
Mutualism (+/+) is a type of symbiosis in which both species benefit
What is commensalism?
Commensalism (+/0) is a type of symbiosis in which 1 species benefits while the other is unaffected
What is Batesian mimicry?
Batesian mimicry is when a palatable or harmless species mimics an unpalatable or harmful model
What is Mullerian mimicry?
Mullerian mimicry is when an unpalatable or harmful species resemble one another so neither is preyed upon
What determines trophic structure?
Feeding relations between organisms
What are primary producers?
Photosynthetic species
What are primary consumers?
Herbivores
What are secondary consumers?
Carnivores
What are tertiary consumers?
Carnivores which eat other carnivores
Why are food chains limited to 4 or 5 trophic levels?
Because of the energy loss between levels
What is the percent of production transferred from 1 trophic level to the next?
10%
What is a food web?
A food web is food chains hooked together, where species can operate on more than 1 trophic level
What is a dominant species?
Dominant species are those in a comunity that have the highest abundance or highest biomass (the sum weight of all individuals in a populations)
What happens when we remove a dominant species from a community?
The entire community structure changes
What is a keystone species?
Key stone species may not be dominant in number, but can affect structure because of their role (niche)
What happens when we remove a keystone species is removed from a community?
Community structure is greatly changes
What is species diversity?
Species diversity is the variety of organisms which make up a community?
What is species richness?
Species richness is the total number of species in the community
What is relative abundance?
Relative abundance is the abundance of different species
What are the 2 components of biodiversity?
- Species richness
- Relative abundance
Can 2 species have the same richness?
Yes, but they have to have a different relative abundance
Explain the latitudinal gradient for diversity:
Species richness generally declines along an equatorial-polar gradient
What other factors affect a community’s biodiversity?
- Size and biogeography
- The bigger the area the greater the species number
- Evolutionary history
- “Older” communities are generally more diverse
What type of habitat supports the most species?
Tropical habitats
What is ecological sucession?
Ecological succession is the sequence of community and ecosystem changes after a disturbance
What is primary succession?
Primary succession occurs where no soil exists when succession begins
What is secondary succession?
Secondary succession begins in an area where soil remains after a disturbance
What are the effects of early-arriving species?
- Facilitate appearance of later species by making the environment more favorable
- May inhibit extablishment of later species
- May tolerate species but have no impact of their establishment
What influences species diversity and composition?
Disturbance
What is disturbance?
Disturbance is an event that changes a community, removes organisms from it, and alters resource availability
What is the nonequilibrium model?
The nonequilibrium model describes communities as constantly changing after a disturbance
How is disturbance characterized?
By frequency and intensity (both have to vary together)
What is the intermediate disturbance hypothesis?
The intermediate disturbance hypothesis states that moderate levels of disturbance can foster greater diversity
What do high levels of disturbance do to species?
High levels of disturbance may excluse many slow-growing species
What do low levels of disturbance do to species?
Low levels of disturbance allow dominant species to exclude less competetive species
