Chapter 54: Community Ecology Flashcards
Community
A group of populations of different species living close enough to interact
Interspecific Interactions
A relationship between individuals of two or more species in a community
Interspecific Competition
- -/- interaction
- Individuals of different species compete for a resource that limits their growth and survival
Competitive Exclusion
- 2 species competing for the same limiting resources cannot coexist permanently in the same place
- Slight reproductive advantage will eventually lead to local elimination of the inferior competition
Ecological Niche
Sum of a species’ use of biotic and abiotic resources in its environment
Resource Partitioning
The differentiation of niches that enables similar species to coexist in a community
Character Displacement
Tendency for characteristics to diverge more in sympatric than in allopatric populations of two species
Predation
- +/- interaction
- One species (predator) kills and eats the other (prey)
Aposematic Coloration
- Bright warning coloration
- Adaptive (predators often avoid)
- Animals with effective chemical defenses will exhibit this
Cryptic Coloration
- Camouflage
- Makes prey difficult to see
Batesian Mimicry
Palatable / harmless species mimics an unpalatable / harmful one
Müllerian Mimicry
Two or more unpalatable species resemble each other
Herbivory
- / -
- Organism eats part of a plant / agla
Symbiosis
Relationship between individuals of two or more species that live in direct and intimate contact with each other
Parasitism
- +/-
- One organism (parasite) derives its nourishment from another organism (host)
Parasite
- An organism that feeds on the cell contents, tissues, or body fluids of another species while in or on the host organism
- Harm but usually do not kill the host
Host
- The larger participant in a symbiotic relationship
- Often provides a home and food for the smaller symbiont
Endoparasites
Parasites that feed on the external surface of a host
Mutualism
- Interspecific reaction that benefits both species
- +/+
Commensalism
- Interaction between species that benefits one species but neither harms nor helps the other
- +/0
Facilitation
- Interaction where species can have positive effects on survival / reproduction of other species
- / +
- Not necessarily living in the direct and intimate contact of a symbiosis
Species Diversity
- Variety of different kinds of organisms that make up a community
- 2 components:
- Species richness
- Relative abundance
Species Richness
Number of different species in the community
Relative Abundance
Proportion each species represents of all individuals in the community
Shannon Diversity (H)
Widely used index to compare diversity based on species richness and relative abundance
Biomass
Total mass of all organisms in a habitat
Invasive Species
Organisms that become established outside their native range
Trophic Structure
- The different feeding relationships in an ecosystem
- Determine the route of energy flow and the pattern of chemical cycling
Food Chain
The pathway along which food energy is transferred from one trophic level to trophic level, beginning with producers
Food Web
Food chains linked together
Energetic Hypothesis
- Suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain
- 10% is stored in the organic matter of each trophic level
Dominant Species
Species in a community that are the most abundant or that collectively have the highest biomass
Keystone Species
A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche
Ecosystem Engineers
- Foundation species
- Species that dramatically alter their environment
Bottom-Up Model
- V–>H
- Postulates an unidirectional influence from lower to higher trophic levels
- N –> V –> H –> P
Top-Down Model
- Predation mainly controls community organization
- P to H to V to N
Biomanipulation
An approach that applies the top-down model of community organization to alter ecosystem characteristics
Disturbance
An event (i.e. storm, human activity) that changes a community by removing organisms from it or altering resource availability
Nonequilibrium Model
Describes most communities as constantly changing after a disturbance
Intermediate Disturbance Hypothesis
States that moderate levels of disturbance foster greater species diversity than do high or low levels of disturbance
Ecological Succession
- Transition in the species composition of a community following disturbance
- Establishment of a community in an area virtually barren of life
Primary Succession
Ecological succession beginning in a virtually lifeless area where soil has not yet formed
Secondary Succession
Occurs when an existing community has been cleared by some disturbance that leaves the soil intact
Evapotranspiration
- The evaporation of water from soil and plants
- A function of solar radiation, temperature, and water availability
Species-Area Curve
All other factors being equal, the larger the geographic area of a community, the more species it has
Pathogens
Disease-causing microorganisms, viruses, viroids, or prions
Zoonotic Pathogens
Pathogens transferred to humans from other animals, either through direct contact with an infected animal or by means of an intermediate species
Vector
- Intermediate species that spreads a zoonotic pathogen
- Often parasites
