AP Bio Ecology

population

group of individuals of one species living @ same place & same time

community

group of popul. living @ same place & same time

ecosystem

all of living & nonliving factors that affect an organism in specific area

biosphere

portion of earth that supports life

niche

organism’s role in ecosystem

population ecology

study of growth, abundance, & distribution of popul.

size (N)

total # of individuals

density

amount of organisms in specific area

dispersion

how popul. are grouped

clumped dispersion

indiv. spaced close together (ex: school of fish)

uniform dispersion

indiv. evenly spaced (ex: apple orchard)

random dispersion

no pattern for dispersion

pyramid shape (age structure)

suggests rapid growth

tiers (age structure)

suggests slow growth; smaller @ top, larger @ bottom

equal sizes/width (age structure)

suggests zero growth (equal @ top & bottom)

type I survivorship curve

most likely to die when old (ex: humans)

type II survivorship curve

equal chance of death @ any age (ex: squirrels)

type III survivorship curve

most likely to die when young (ex: oysters)

broadcast spawning

oyster can’t move → can’t reproduce asexually → produce & directly release gametes into water → eaten by other organisms

biotic potential

max growth rate of popul. under ideal conditions

carrying capacity

max # of indiv. that can be sustained by a particular habitat

density dependent limiting factors

agents whose limiting effects become more intense as popul. becomes larger

* affects larger rather than smaller popul.
* ex: disease, competition for food

density independent limiting factors

occur regardless of popul. size but still effects popul.

* ex: fire, volcanic eruptions, hurricanes

reproductive rate equation

r = (births - deaths)/N

* N = popul. size

intrinsic rate

reproductive rate = max; affects indiv.

* ex: bacteria

zero popul. growth

births - deaths = 0

exponential growth

as popul. grows, grows faster but eventually crashes due to density dependent factors (boom & bust cycles)

logistic growth

starts as exponential → stops @ carrying capacity due to density dependent factors

R-selected species

* exhibits rapid growth
* J-shaped curve (exponential)
* opportunist & pioneer species
* short-lived, lots of offspring, little parental care
* ex: mosquitos, mice

K-selected species

* relatively constant @ carrying capacity
* S-shaped curve (logistic)
* long-lived, few offspring, lots of parental care
* ex: elephants, humans

competitive exclusion principle

states no two species can sustain coexistence if they occupy same niche in ecosystem

* leads to either extinction or resource partitioning

resource partitioning

two species do a more narrow niche to avoid competition in ecosystem

fundamental niche

niche an organism occupies in absence of competing species (extinct)

realized niches

niche competition organisms occupy; prevents competition; occurs after resource partitioning

do niches overlap?

no overlap

symbiosis

relationship btwn two or more species

mutualism

type of symbiosis where both species benefit

commensalism

type of symbiosis where only one species benefits & other isn’t benefitted or harmed

parasitition

type of symbiosis where one species benefits & other is harmed

true predator (heterotroph)

kills & eats animals (ex: parasite)

parasite

organism that lives on another & feeds on its tissues

parasitoids

insects that lay eggs inside of host → larvae devour host until fully developed (ex: wasp & catapillar)

herbivore (plant predator)

feed on plant matter

* granivore - grains
* frugivore - fruits
* grazer - grass
* browser - leaves

ecological succession

series of changes in community structure → ultimately results in stable community

primary succession

occurs in an area that hasn’t been lived in yet (brand new habitat)

* involves pioneer species (good at colonizing)
* area has all rock, no soil

climax community

end result of succession; stable; same types of popul.

pioneer species

first species in new habitat

* can live in marginal habitat (barely supports life)
* bad at competition
* ex: lichen = composite species (more than one species)
* made up of algae, yeast, & fungi → mutualistic relationship
* lives on bare rock & breaks it down into soil

secondary succession

there has been life where it occurs

* when climax community was disturbed by natural disaster or human activity
* faster than primary b/c has soil already

succession is…

less predictable than once thought

energy pyramid

shows amount of energy @ each trophic level

trophic level

feeding level in food chain

primary consumer

aka first order heterotroph

secondary consumer

aka second order heterotroph

tertiary consumer

aka third order heterotroph

primary producer

aka autotroph

* does photosynthesis, makes its own energy

bar

all species of trophic level in ecosystem

arrows

shows flow of energy in food chain

as you move up in trophic level…

10% of energy moves up

biomass

amount of matter in living thing

biomass pyramid

shows amount of biomass @ each trophic level

why does biomass pyramid mirror energy pyramid

b/c energy makes up biomass

biome

group of similar organisms

abiotic factors that determine where each biome is

temp & precipitation

tropical rainforest

year round high temp & high precipitation

desert

winter: low temp, low precip

summer: high temp, low precip

taiga

winter: low temp, moderate precip

summer: moderate temp, moderate precip

* mostly conifers

deciduous forest

winter: low temp, moderate precip

summer: high temp, moderate precip

chaparral

winter: low temp, moderate precip

summer: high temp, moderate precip