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scientific study of interactions among organisms and between organisms and their environment


a group of organisms so similar to one another that they can breed and produce fertile offspring

Sterile hybrid

mules, ligers, tigons are what kind of species?


a group of organisms of the same species populating a given area


Groups of organisms inhabiting the same region and interacting with each other

Population Density

number of individuals per unit area

Clumped dispersion

most common-- individuals stay in patches or groups

Uniform dispersion

Evenly spaced--happens from territoriality, species become competitive, uncommon.

Random dispersion

When individuals are attracted to a certain key factor and is when individuals are independent of everyone else, uncommon.

exponential growth

growth pattern in which the individuals in a population reproduce at a constant rate, ex: humans. Curve is J shaped. There are unlimited resources.

Logistic Growth

growth pattern in which a population's growth rate slows or stops following a period of exponential growth. S shaped curve.

Carrying Capacity

Largest amount of a population that can be supported by an area. Represented by variable K.

R Selected Population

high death rate, reproduce quickly, unlimited resources, short life span, numerous offspring, no parental care. Exponential. Density Independent

K Selected Population

low death rate, few vital offspring survive, maximum population size, long life span, off spring are large, compete for resources, density dependent


a group people having approximately the same age

Type I Survivorship

Humans, they have few offspring, good parental care, and live between 0-60 years. K Selected.

Type II Survivorship

Squirrels and song birds, they have medium "litter" offspring, short span parental care, constant death rate. Neither K selected or R selected.

Type III Survivorship

Oysters, they have large offspring, no parental care, and they die after birth, R selected.


big-bang reproduction-- produce a lot of offsprings all at once and hope they survive. Ex: agaves century plants and oysters


repeated reproduction, repeat annually for or every few years.

trade off

An organism's allocation of its limited energy or other resources to one structure or function at the expense of another.

density dependent

factor that impacts populatios more when density is high. controls include: disease, parasitism, competition for resources, territoriality, toxic metabolic wastes, and predation.

density independent

factors that limit populations but are unrelated to population density , ie hurricane, flood, fires, pesticides

Prey and Predator relationship

If the prey population increases, the predator population increases as well since it depends on it for food.


Rapid growth population with many offspring

United States

slow growth from baby booming


decline in population.

Community ecology

A group of populations that inhibit a particular area. The study of a whole array of interacting species.


Physical location that an organism lives


how they make a living, biological role


biotic components interacting with Abiotic components (soil, climate, water)


Living together, the relation between two different species of organisms that are interdependent


one species benefits and the other is neither harmed nor benefitted (+/0) ex: barnacles on a whale.


When both organisms benefit. (+/+) Bees pollinating flowers


host is harmed but parasite benefits (+/-)


One organism kills the other. This keeps the prey population from exceeding the carrying capacity.


Two or more individual organisms of a single species (intraspecific competition) or two or more individuals of different species (interspecific competition) attempting to use the same scarce resources in the same ecosystem. (-/-)


organisms that can blend in their environment

warning coloration

Conspicuous patterns and colors that predators learn to recognize as: "Avoid me!"

batesian mimicry

A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators.

mullerian mimicry

when two or more poisonous species resemble each other and gain an advantage from their combined numbers

moment of truth defense

Last minute, last chance trick prey use.

resource partitioning

2 species evolve different behaviors or morphological traits that allow them to use a resource in different ways-->less competition, divide their niche

community stability

species with similar niches can coexist without interspecific competition as long as they differ in
1) horizontal or vertical position (habitat)
2)temporal relations (time they are up, noct/diurnal)
3)stage of development

keystone species

species whose role in an ecosystem in an ecosystem is more important than others, such as a sea otter, sea stars, grizzly bear, prairie dogs. (Sea stars keep mussels under control. The removal of it decreases diversity.)

island biogeography

theory that, as species richness increases in an isolated habitat, immigration decreases and extinction increases to maintain equilibrium of species

Food chain

simple model that shows how matter and energy move through an ecosystem (example: plankton -->minnow -->fish --> shark)

Trophic level

A level in the food chain based on source of food.

1st level

autotrophs/primary producers

food webs

more complex, interrelationships among various organisms at each trophic level. ex. bears eat berries (pp) and mammals(con).

Energy pyramid

a diagram that shows the amount of energy that moves from one feeding level to another in a food web

Energy line up

primary producer (100%), Primary consumer (10%), Secondary Consumer (1%), Tertiary Consumer (.1%), Quaternary (.001%) energy.


total dry mass, a given type in a given area (g/m2)


phytoplankton are consumed too quickly

Numbers pyramid

shows number of individuals, predators at stake of extinction.

gross primary production

the amount of photosynthesis per unit time

Net primary production

the amount of vegetation added to ecosystem, Biomass per unity area per unit time (NPP-R)

primary productivity

rate at which producers in an ecosystem build biomass

Dissolved Oxygen

oxygen released into the water by photosynthesis. Sources: Diffusion and Photosynthesis. Sink: Cellular respiration. Solubility: Temperature (Cold>Hot), Salinity (Fresh>Salt), Altitude (Sea>High), Depth (Shallow>Deep)

Water Cycle

Evaporation of liquid water by solar energy, condensation of water vapor into clouds, and precipitation. Transpiration by plants. Runoff +Groundwater return water to ocean (resettle)

Carbon Cycle

CO2 reservoir is from fossil fuels. CO2 goes into atmosphere, reduced by photosynthesis, decomposed detritus and C-compounds in water & cellular respiration return it to atmosphere

Nitrogen Cycle

the continuous sequence of events by which atmospheric nitrogen and nitrogenous compounds in the soil are converted, as by nitrification and nitrogen fixation, into substances that can be utilized by green plants, the substances returning to the air and soil as a result of the decay of the plants and denitrification.

Phosphorus cycle

the movement of Phosphates in the atmosphere; where phosphate runs off rocks and is absorbed in soil. Plants then dissolve this and herbivores obtain Phosphorus by eating the plants, and the carnivores by eating the herbivores. Phosphorus is excreted as feces and urine from animals and returns in decomposition of animals.

energy transfer

sun, producer, consumer, decomposer


over-enrichment of a body of water as a result of excessive nutrient loading, often resulting in the depletion of dissolved oxygen and detrimental to living organisms.

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