Ch 41 - species interactions

interspecific interactions

relationships between species in a community. for example:

• predation

• commensalism

• competition

• etc

interspecific competition (-/-)

when species compete for a resource that limits their growth or survival

competitive exclusion

local elimination of a competing species

ecological niche

the specific set of biotic and abiotic resources used by an organism

resource partitioning

similar species can coexists if there are significant differences in niches

character displacement

a tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species

exploitation (+/ -)

one species benefits, while the other is harmed. like parasitism and predation

cryptic coloration

camouflage, makes prey difficult to spot

aposematic coloartion

warning colors on organisms

batesian mimicry

harmless species mimics a harmful one

endoparasites

inside the body of the host

ectoparasites

on the outside of the host

positive interactions

any interactions in which one species benefits and neither is harmed

species diversity

how many species are in a community

species richness

number of different species

relative abundance

the proportion each species represents of all individuals in the community

trophic structure

feeding relationships between organisms

food chains

link the trophic levels

food web

branching food chain (more complex than food chain)

dominant species

those that are most abundant/ have the highest biomass

keystone species

have a strong control on their community due to their niches

ecosystem engineers

cause physical changes in an environment ( like beavers )

biomass

total mass of all organisms in a habitat

bottom-up model

undirect influence lower to higher trophic levels

top-down model

proposes that predation controls the organization

biomanipulation

application of top-down model used to improve polluted lakes

disturbance

an event that changes a community by removing organisms or altering resource availability

nonequilibrium model

describes communities as constantly changing after disturbances

ecological succesion

the sequence of change in community composition after a disturbances

the two types of ecological sucession

• primary succession - occurs in lifeless area where there’s no soil

• secondary succession - begins in an area where soil remains after a disturbance