#15-Nature Of Communities Flashcards
What is a physically defined community?
Encompasses all species in an area
What is a biological,y defined community?
All species associated with a region/ general area
- emphasis importance of abundant species
3 ways to study organisms in a community
- Taxonomic affinity- all of one species (ex:birds)
- Guild- group of species that use the same resources
- Functional group- species that functions in a similar way but don’t use the resource in the same way
What is a food web?
Organizing species based on tropic or energetic interactions
What is a downfall to food webs?
Doesn’t say much about the strength of the interactions I’d their importance in the community
- some organisms can feed on multiple levels
What is an interaction web?
More accurately describes both the tropic (vertical) and non tropic (horizontal) interactions
What is a community structure?
The number of species in a community
What is species evenness?
Relative abundances compared with one another
What is species diversity?
Combines species richness and species evenness
What is the Shannon index?
Species diversity index
Sum of pi x ln(pi)
What is biodiversity
Describes diversity at multiple spatial scale from genes to species to community
What is genetic diversity?
Affects species in a community and the diversity of the species
What are rank abundance curves?
Plot the proportional abundance of each species relative to others in rank order
- can tell if one is dominant over the other
- can tell if one is having a negative effect on the other
What is species composition?
Identity of species in a community
What is species accumulation curves?
Richness is plotter as a function of the total number of individuals that have been counted
What are direct interactions?
Occur between 2 species
What are indirect interactions?
Occur when the relationship between 2 species is mediated by a 3rd species
How can we see indirect effects on s community?
When a species is removed
What is a tropic cascade?
When one level is affected and the levels below are also impacted in a negative or positive way
What is tropic facilitation?
Consumed is indirectly facilitated by a positive interaction between its prey and another species
What is a competitive network?
Competitive interactions among multiple species in which every specie negatively interacts with every other species s
What is interactions strength ?
Magnitude of the effect of one species on the abundance of another species
What is a dominant/ foundation specie ?
Have large effects on other species and thus species diversity, by virtue of their considerable abundance of biomass
What are ecosystem engineers?
They create and modify or maintain physical habitat for themselves and other species
What is a keystone species?
They have strong effects because if their roles in the community
What are communities?
Groups of interacting species that occur together at the same place and time
