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The flashcards below were created by user
ashk6510
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Communities
- group of interacting species at same place and time
- synergistics: interactions make communities into something more than the sum of parts
- considered to be fundamental unit of landscape
- often classified by physical or biological characteristics
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Subset of species used to define communities
- Taxonomic affinity: "birds"
- Guild: group of species using same resources "birds, bees, and bats are all pollen-eating animals"
- Functional Group: includes species that function in a particular way but do not necessarily use the same resources misquetos and aphids
- Food Web: based on trophic, energentic, interactions
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Food Web
- organzed by tropic levels- group of species that have similar wayto obtain energy
- primary producer: autotrophs
- primary consumers: herbivores
- secondary consumers: carnivores
- tertiary consumers: carnivores
- does not tell about strength of interaction
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Interaction Web
- used to describe both trophic and non-trophic interactions among species
- omnivores: feed on more than one trophic level
- horitontal interactions: competition and positive interactions
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Community Structure
- set of characteristics that shape a community
- include species diversity and species composition
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Species Diversity
- a measure that combines relative number of species to relative abundance
- Shannon Index: calculated number showing diversity lowest 0 can go to infinity, the higher the value the more diversity
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Species richness
number of species
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Species eveness
tells commonness or rarity of species
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Biodiversity
describe the diversity of important ecological entities that span multiple spatial scales, genes to species to communities
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Rank abundance curve
plots proportional abundance of each species to the others in rank order from most to least abundant
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Species Accumulation Curve
- calculated by plotting species richness as a function of the sampling effort
- theoretically the more sampling done the line levels off revealing fewer or no new species
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Species Composition
identity of the species present in the community
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Direct Interactions
occur between 2 species and include trophic and non-trophic interactions
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Indirect Interactions
relationship between 2 species is mediated by a 3rd or more species
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Trophic Cascade
- rate of consumption at one level results in a change in species abundance or composition at lower trophic levels
- kelp forest, urchins and otters
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Tropic Facilitation
- consumer is indirectly facilitated by a positive interaction between its prey and another species,
- juncus helped iva plant grow in turn helping aphid population
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Competitive Networks
- competitive interactions among multiple species in which every species negatively interacts with every other species
- circular web rather than linear
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Interaction Strength
- effect of one species on the abundance of another
- can be measured experimentally by removing one species(interactor species) from the community and looking at the effect on the other species(target species)
- if removal of interactor resluts in large decrease in target species, interaction is strong and positive
- if the abundance of the target increase the interactor species has srong negative effect
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Dominant Species
- aka foundation species
- large or abundant species or biomass in community, usually trees, provide habitat or food for other species
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Ecosystem Engineer
are able to create. modify, or maintain physical habitat for themselves and other species
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Keystone Species
- large effect on community not because of thier abundance but because of the roles they play
- influence community structure indirectly , by trophic means
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Interactions are context-dependant
changeable under different enviromental conditions
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