Ch 54 Community Ecology Flashcards
community
group of populations of different species living in close enough proximity to interact
ecological niche
the specific set of biotic and abiotic resources that
an organism uses in its environment
species richness
the number of species in a community
species abundance
the number of individuals per species
species diversity
the number and relative abundance of species found in a given biological organisation
diversity index
a quantitative measure that reflects the number of different species and how evenly the individuals are distributed among those species
Shannon diversity index
equation that tells you how diverse the species in a given community are
Diversity often varies with
Environmental conditions
What influences species abundance and diversity?
Species interactions
Competition
a -/- interaction that occurs when individuals of different species compete for a resource that limits
the survival and reproduction of each species
Competitive exclusion
the inevitable elimination from a habitat of one of two different species with identical needs for resources
Species can coexist if:
They use different resources
Fundamental niche
the set of conditions within which a species can live in the absence of competitors
Realized niche
the set of conditions actually used by given animal (pop, species), after interactions with other species (predation and especially competition) have been taken into account.
Potential impacts of competition - 2 things
- Reduced local diversity
2. Non-native species suppresses native species
Herbivory
an exploitative (+/-) interaction in which an organism—an herbivore—eats parts of a plant or alga, thereby harming it
Predation
a +/- interaction between species in which one species, the predator, kills and eats the other, the prey
Parasitism
a +/- exploitative interaction in which one
organism, the parasite, derives its nourishment from
another organism, its host, which is harmed in the process
ectoparasite
a parasite, such as a flea, that lives on the outside of its host.
endoparasite
a parasite, such as a tapeworm, that lives inside its host.
Mutualism
an interspecific interaction that benefits both species (+/+)
Commensalism
An interaction between species that benefits one of the species but neither harms nor helps the other (+/0)
trophic structure
the feeding relationships between organisms
Food chain
The transfer of food energy upward from its source
Food web
a group of food chains are linked together
Facilitators
have positive effects on survival & reproduction of other species
Facilitation
describes species interactions that benefit at least one of the participants and cause harm to neither
Succession
The disturbed area may be colonized by a variety of species, which are gradually replaced by other species, which are in turn replaced by still other species
Plant succession
changes in abiotic & biotic conditions induced by the vegetation
Primary succession example
Glacier retreating
Process of plant succession - 3 steps
- conditions shift from low nutrient/high light high nutrient/low light
- species colonize & change conditions
- early-arriving species influence later-arriving species
Secondary succession
occurs when an existing community has been cleared by a disturbance that leaves the soil intact, as in Yellowstone following the 1988 fires
