Ecology: Community Eco Flashcards
Individualistic hypothesis
Communities assemble by chance of species with similar abiotic requirements
Interactive hypothesis
Communities assemble by chance of closely linked species
Tropic levels are defined by
The number of steps though which energy passes to reach organisms in it
List basic steps of trophic levels
Primary producer-autotrophsPrimary consumersSecondary consumersTertiaryQuaternary
Ecological pyramid measures
Biomass- measure of weight of tissues
Energy pyramid describes
The transfer of energy between trophic levels. Only 10% gets consumed from lv to lv
Top-down effect
Abundance of lower trophic levels depends on consumers
Bottom-up effect
Abundance of higher levels depends on lower lvs/ producers
Trophic cascade
When a level is changed (ex population) it sends a cascade of effects trough the chain (usually alternating in increasing/decreasing of other levels)
Species richness
Number of (different) species in a community
Species evenness
The relative abundance of species (to each other) in a community
Species diversity =
Sp evenness + sp richness
For any given sp richness, diversity (H) increases with
Species evenness and vice versa
Communities with very high or low disturbance have _____ species diversity than communities with moderate disturbance
Lower
Good colonizers are
R-selected
Good competitors
K-selected
Species diversity is highest here disturbance is moderate because
It allows both colonizers and competitors to coexist (K+r)
Good competitors (K) reside on the _____ side of the curve
Left side
Colonizers (r) reside alone on the ______ side of the curve
Right
Communities are adapted to a specific frequency and intensity of disturbance.
True, ex: adaptations to moderate fires
Diversity-stability hypothesis
- Disturbances in diverse communities is dampened by large # of interactions2. The effect of disturbance is less than it would be in a species community without diversity
Succession
Transition in species composition over time
Primary succession
Bare soil, no organisms
Secondary succession
Organisms present with soil
Successional pathway
Good colonizers exist earlyGood competitors exist later (near K)
Directional succession
Progressive change in species comp
Cyclical succession
Change which in the end results in the original community
Invasive species
Species that disrupt communities and suddenly become the dominant species.Changes ecosystem structure and function
Invasive species means that it is non-native
False
Environmental disturbance promotes ______ which can alter ______ and promote even ___-
Biological invasionMore invasion
