Chapter 54 - Community Ecology Flashcards
community
All the organisms that inhabit a particular area; an assemblage of populations of different species living close enough together for potential interaction.
interspecific interaction
A relationship between individuals of two or more species in a community.
interspecific competition
Competition for resources between individuals of two or more species when resources are in short supply.
competitive exclusion
populations of two similar species compete for same limited resources → one population will use resources more efficiently and have reproductive advantage → eventually leads to elimination of other population.
Competitive Exclusion Principle: two species cannot permanently coexist in same community if niches are IDENTICAL.
ecological niche
The sum of a species’ use of biotic and abiotic resources in its environment.
resource partitioning
The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species.
character displacement
The tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species.
predation
An interaction between species in which one species, the predator, eats the other, the prey.
cryptic coloration
Camouflage that makes a potential prey difficult to spot against its background.
aposematic coloration
The bright warning coloration of many animals with effective physical or chemical defenses.
Batesian mimicry
A type of mimicry in which a harmless species like a species that is poisonous or otherwise harmful to predators.
Müllerian mimicry
Reciprocal mimicry by two unpalatable species.
herbivory
In interaction in which an organism eats parts of a plant or alga.
symbiosis
An ecological relationship b/w orgs of two diff species that live t/g in direct and intimate contact.
parasitism
A symbiotic relationship in which one organism, the parasite, benefits at the expense of another, the host, by living either within or on the host.
parasite
An organism that feeds on the cell contents, tissues, or body fluids of another species (the host) while in or on the host organism. Parasites harm but usually do not kill their host.
host
The larger participant in a symbiotic relationship, often providing a home and food source for the smaller symbiont.
endoparasite
A parasite that lives within a host.
ectoparasite
A parasite that feeds on the external surface of a host.
mutualism
A symbiotic relationship in which both participants benefit.
commensalism
A symbiotic relationship in which one organism benefits but the other is neither helped nor harmed.
facililtation
An interaction in which one species has a positive effect on the survival and reproduction of another species without the intimate association of a symbiosis.
species diversity
The number and relative abundance of species in a biological community.
species richness
The number of species in a biological community.
relative abundance
The proportional abundance of different species in a community.
Shannon diversity (H)
An index of community diversity symbolized by H and represented by the equation H = -(pA ln pA + pB ln pB + pC ln pA + . . .), where A, B, C . . . are species, p is the relative abundance of each species, and ln is the natural logarithm.
invasive species
A species, often introduced by humans, that takes hold outside its native range.
trophic structure
Feeding relationships among orgs w/i a community → det route of energy flow and pattern of chemical cycling.
food chain
The pathway along which food energy is transferred from trophic level to trophic level, beginning with producers.
- I.e. xfr of energy upward fr autotrophs → primary consumers → secondary → tertiary…
food web
The interconnected feeding relationships in an ecosystem (w/i a community).
- I.e. branching food chain w complex trophic interactions
energetic hypothesis
The concept that the length of a food chain is limited by the inefficiency of energy transfer along the chain.
biomass
The total mass of organic matter comprising a group of organisms in a particular habitat.
dynamic stability hypothesis
The concept that long food chains are less stable than short chains.
dominant species
Species w substantially higher abundance or biomass than other species in a community.
- Exert powerful control over occurrence and distribution of other species.
- Hypothesis: competitively superior; more successful at avoiding predators and disease.
keystone species
Not necessarily most abundant/greatest biomass but exerts strong control on community structure by the nature of its ecological role or niche.
- Recall: eco niche: sum of species use of a/biotic resources.
- Often identified by removal experiments
- May keep other species in check
ecosystem engineers (foundation species) and facilitators
Ecosystem engineers and facilitators are both imp species in a community:
- Eco engineers influence community structure by causing physical changes in the environ.
- Facilitators have pos effect on survival/reprod of other species (+/+ or +/0 interspecific relations)
bottom-up model
A model of community orgz - unidirectional influence fr lower to higher trophic levels.
- I.e. mineral nutrients/abiotic factors influence community orgz by controlling plant or phytoplankton # → control herbivore # → control predator #.
top-down model
Model of community orgz - unidirectional influence fr higher to lower trophic levels.
- I.e. predation influences comm orgz by controlling herbivore # → control plant or phytoplankton # → control nutrient levels.
- Aka trophic cascade model.
biomanipulation
An approach that applies the top-down model of community organization to alter ecosystem characteristics. For example, ecologists can prevent algal blooms and eutrophication by altering the density of higher-level consumers in lakes instead of by using chemical treatments.
disturbance
A natural or human-caused event that changes a biological community and usually removes organisms from it. Disturbances, such as fires and storms, play a pivotal role in structuring many communities.
nonequilibrium model
A model that maintains that communities change constantly after being buffeted by disturbances.
intermediate disturbance hypothesis
The concept that moderate levels of disturbance can foster greater species diversity than low or high levels of disturbance.
ecological succession
Transition in the species composition of a community following a disturbance; establishment of a community in an area virtually barren of life.
primary succession
Occurs in an area where there were originally no organisms present and where soil has not yet formed.
*not covered in lecture
secondary succession
Occurs where an existing community has been cleared by some disturbance that leaves the soil or substrate intact.
*not covered in lecture
evapotranspiration
Total evaporation of water fr an eco, incl water transpired by plants and evaporated fr a landscape, typ measured in mm/yr.
*not covered in lecture
What does a species-area curve indicate?
Species richness is directly related to a community’s geo size.
- The biodiversity pattern that shows that the larger the geographic area of a community is, the more species it has.
Species richness on islands deps on island size and distance from the mainland.
- Island equilibrium model maintains that species richness on an eco island reaches an equilibrium where new immigrations are balanced by extinctions.
**NOT covered in lecture
pathogen
An organism, virus, viroid, or prion that causes disease.
*NOT covered in lecture
zoonotic pathogen
A disease-causing agent that is transmitted to humans from other animals.
*NOT covered in lecture
vector
An organism that transmits pathogens from one host to another.
What is the competitive exclusion principle?
Competitive Exclusion Principle: two species cannot permanently coexist in same community if niches are IDENTICAL.
Recall - Ecological niche: sum of species use of a/biotic resources; its “eco role” or how it fits in.
Diff b/w fundamental and realized niche.
Fundamental niche: niche potentially occupied by a species
Realized niche: portion actually occupied in a partic environ.
Name several predatory adaptations.
Predatory adaptations - help locate, identify, subdue, and capture prey.
- Speed
- Heat-sensing
- Camouflage
- Vision
- teeth
- talons
- venom
Name several prey adaptations.
Prey adaptations - defenses to avoid detection or defer predation.
- Behavioral: hiding, fleeing, schooling/grouping, active defense
- Physical: coloration, mech/chem defenses
Benefits of communities w higher diversity
Benefits of communities w higher diversity:
- More productive and more stable in productivity
- Better able to withstand and recover from environ stresses
- More resistant to invasive species (established outside native range)
autotrophs vs heterotrophs
Autotrophs - use solar (or chem) energy to build molecules themselves
- Plants
- Psynth/chemosynth bac; some protists
Heterotrophs - dep on output fr other orgs
- Fungi
- Animals
- some bac/protists (predators and parasites)
Based on indexes such as Shannon diversity, is a community of higher species richness always more diverse than a community of lower species richness? Explain.
Not necessarily if the more species-rich community is dominated by only one or a few species.