APES Ch. 4

competition

both species are harmed

exploitative

one species benefits and the other is harmed
- predetation, paratism, herbivory

mutualism

both (or more) species benefit

competition

multiple organisms seek the same limited resources
- food, space, water, shelter, mates, sunlight

intraspecific competition

between members of the same species
- high population density = increased competition
- growth limiting factor

interspecific competition

between members of two or more species
- strongly affects community composition
- leads to competitive exclusion or species coexistance

competitive exclution

one species completely excludes another from using the resource
(zebra mussels displaced native mussels)

species coexistance

neither species fully excludes the other from resources, so both live side by side (still a struggle)
- produces stable point of equilibrium with stable population sizes
- species minimize competition by using only a part of the available resource (niche)

fundamental (idealized) niche

the full niche of a species
- fulfills all roles or uses all resources it can

realized niche

the portion of the fundamental niche that is actually filled
- due to competition or other species interactions

resource partitioning

species use different resources or they use shared resources in different ways
(Ex: one species active in day, one at night)

character displacement

competing species diverge in their physical characteristics
- due to evolution of traits best suited to the resources they use
- results from resource partitioning

competition is reduced when...

two species become more different

exploitation

one member exploits another for its own gain (+/- interaction)

predation

process by which individuals of one species (predator) capture, kill, and consume individuals of another species (prey)
- structures food webs
- number of predator prey influences community competition

increased prey population increases predator population then ...

predators survive and reproduce and prey population decreases and predators starve (cyclical)

predation has evolutionary ramifications

- natural selection leads to evolution of adaptations that make predators better hunters
- individuals that are better at catching prey live longer, healthier lives and take better care of offspring

prey face strong selection pressures

at risk of immediate death
- develop elaborate defenses against being eaten

defenses against being eaten

- cryptic coloration (camouflage)
- warning coloration: bright colors mean it won't taste good or species is really good at mimicry
- mimicry: look like something else that isn't prey (poisionous)

paratism

a relationship in which one organism (parasite) depends on another (host) (+/-)
- for nourishment or some other benefit
- the parasite harms, but doesn't kill the host
- some are free living so infrequent contact with host (ticks, sea lamprey)
- some live within the host (disease, tapeworms)

coevolution

hosts and parasites become locked in a duel of escalating adaptations (2+ organisms)
- called evolutionary arms race
- each evolves new response to the other
- any species that evolves with other species (dogs and horses)

herbivory

animals feed on the tissues of plants
- widely seen in insects
- may not kill the plant but affects growth and survival

defenses against herbivory

- chemicals: toxic or distasteful
- thorns, spines, or irritating hairs
- other animals: protect the plant

mutualism

two or more species benefit from their interactions (+/+)

symbiosis

mutualism in which the organisms live in close physical contact (isn't being done for the other species or parasitism)
- each partner provides a service that the other needs (food, protection, housing, etc.)
- microbes within digestive tracts, coral and algae

pollination

bees, bats, birds, and others transfer pollen from one flower to another, fertilizing its eggs
- pollinate in exchange for nectar
- bees pollinate 73% of crops

amensalism

a relationship in which one organism is harmed while the other is unaffected (-/0)
- difficult to confirm, because usually one organism benefits from harming another

allelopathy

certain plants release harmful chemicals (ex: black walnut trees and tomatoes)

commensalism

a relationship in which one organism benefits while the other remains unaffected (+/0) (ex: clownfish)

community

an assemblage of populations of organisms living in the same place at the same time
- members interact with each other
- interactions determine structure, function, and species composition of the community

Energy passes through _____

trophic levels

trophic levels

rank in the feeding hierarchy
- producers (autotrophs)
- consumers (herbivores, carnivores, omnivores)
- detritavores (eat already dead stuff) and decomposers (more passive)

less and less energy is available in each successive trophic level

each level contains only 10% of the energy of the previous trophic level below it
- also fewer organisms and biomass at higher trophic levels

food chain

a series of feeding relationships

food web

a visual map of feeding relationships and energy flow
- greatly simplified
- are about energy transfers

trophic levels organization

1. teritary consumers (ex. hawks)
2. secondary consumers (fish, rodents)
3. primary consumers ( detritavores)
4. producers (plants)

keystone species

has a strong or wide reaching impact (often least abundant, at the top, large bodied)
- far out of proportion to its abundance
- removal of keystone species has substantial ripple effects that alter the food chain

trophic cascade

predators at high trophic levels indirectly affect populations at low trophic levels
- by keeping species at intermediate tropic levels in check

ecosystem engineers

physically modify the environment
- beavers, prairie dogs, ants, zebra mussels

communities experience many types of disturbances

- removal of keystone species, spread of invasive species, natural disturbances
- human impacts lead to major community changes

resistance

community of organisms resits change and remains stable despite the disturbance

resiliance

a community changes in response to a disturbance but later returns to its original state
- a disturbed community may never return to its original state

succession

the predictable series of changes in a community following a disturbance

primary succession

disturbance removes all vegetation and or soil life
- glaciers, drying lakes, volcanic lava

pioneer species

the first species to arrive in a primary succession area
- lichens

secondary succession

a disturbance dramatically alters, but does not destroy, all local organisms
- fires, hurricanes, farming, logging
- remaining organisms form "building blocks" which help shape process of succession

climax community

remains in place with few changes until other disturbance restarts succession

communities may undergo shifts

- community dynamics are more variable and less predictable than thought
- conditions, competition, change may affect change to another state

phase (regime) shift

the overall character of the community fundamentally changes
- some crucial threshold is passed, a keystone species lost or exotic species invades

invasive species

non-native organisms that spread widely and become dominant in a community
- growth limiting factors are removed or absent
- major ecological effects
- not all invasive species are bad: European honey bee

techniques to control invasive species

- remove them manually
- applying toxic chemicals
- drying them out
- depriving them of oxygen
- stressing them with heat, sound, electricity, carbon dioxide, or ultraviolet light
control and eradication are hard and expensive; prevention is the best policy

ecological restoration

efforts to restore communities
- human changed ecosystems can be restored by humans
- restoration informed by restoration ecology (the science of restoring an area to earlier condition)
- difficult, time consuming, expensive
best to protect instead of degredation

biome

major regional complex of similar communities recognized by
- plant type and vegetation structure
- temperature and precipitation, soil type and atmospheric circulation

climatographs

a climate diagram showing
- mean monthly temp and precipitation of an area
- similar biomes occupy similar latitudes

altitudes create ______

latitudinal patterns (climate and vegetative communities change with altitude)

rainshadow effect

air going over a mountain releases moisture
- creating an arid region on the other side