lecture 21- community ecology Flashcards
what is a community
all the populations of different species that live and interact in the same place at the same time
what is interspecific competition
when different species compete for a particular resource that is in short supply
what is competitive exclusion
local elimination of one of the two competing species
one is better/stronger than the other
what is an ecological niche
all of the organism’s use of the biotic and abiotic resources in its environment
optimal conditions that are characteristic of a species
what is the competitive exclusion principle
two species cant coexist in a community of their niches are identical, too much competition
two species can coexist if their niches are different
what is a fundamental niche
potential ecological niche for an organism if it had no competition
what is a realized niche
the niche the organism actually occupies in the presence of competition
can ecologically similar species coexist
yes if theres one or more significant difference in their niche
what is resource partitioning
differentiation of niches
sharing of resources but the areas dont overlap
what is character displacement
tendency of characteristics to be more divergent in sympatric populations compared to allopatric populations
competing species evolve different niches to avoid competition
will species that live together have greater differences than species that apart
yes there is less niche overlap
how does natural selection affect predation
it shapes the body forms and behaviours of both predator and prey
what are the prey strategies
coloration
mimicry
what is aposematic coloration
warning coloration
bright colors signify chemical defences
what is cryptic coloration
camouflage
what is batesian mimicry
harmless species imitating a harmful species
what is mullerian mimicry
when two harmful species resemble eachother
what do plants do to prevent being eaten
evolution of spines and tough leaves
chemical defenses
what is commensalism
one species benefits while the other is not harmed
what is coevolution
the evolution of two species where they both depend on the other one evolving to evolve
what is a dominant species
species that is the most abundant or has the most biomass
what is a keystone species
not most abundant but have important ecological roles
what is a food web
movement of energy from one species to another in the community
move complex and accurate than food chain
what is ecological succession
transition in species composition in disturbed area over time
what are the steps of primary succession
primary succession begins in lifeless area where there is no soil
only autotrophic prokaryotes are present
mosses and lichen colonize and create soil
then growth of grass, shrubs and trees
what are the steps of secondary succession
the soil is left intact after disturbance
herbaceous species grow first
woody shrubs replace herbs
trees replace shrubs
what is it called when the community is stable
climax community
what is a biome
climax community that has remained stable for a long time
are disturbances good for the ecosystem
yes, they allow a large variability in species composition
why are human disturbances bad
they usually reduce species diversity greatly
types of human disturbances
agriculture
forest clearing
ocean trawling
what is eutrophication and steps
excess algal growth (from increased nitrates and phosphates from chemicals) that prevents sunlight from passing through and reaching bottom of lake
bacteria will break down the dead algae and use up all the oxygen
oxygen poor environment: organisms cant live there
