Unit 13: Ecology

Organism

single member of a specific species

Species

group of organisms able to successfully interbreed & create fertile offspring

Population

all members of a species within a specific location

Community

all populations interacting within a specific location

Ecosystem

a specific location in which both biotic & abiotic factors interact

Biome

large geographic area characterized by specific kinds of plants, animals, & climate

Competition

struggle for limited resources

Interspecific

between members of different species

Intraspecific

between members of same species

Predator/Prey

animals may exist in a relationship where one hunts & kills while the other hides & avoids

• evolution/adaptation occurs between the two

• population of each species is interdependent

Symbiosis

close interaction between 2 organisms in which at least one benefits (3 types)

Mutualism

both organisms benefit in the relationship

Commensalism

one organism benefits, the other is unharmed

Parasitism

one organism benefits & the other loses energy/is harmed

Abiotic factors

non-living parts of the ecosystem

Tolerance curve

graph that represents the success of a species vs. a specific abiotic factor

Optimal range

the variation in a factor that allows for population growth

Zone of intolerance

the extreme range of a factor that prevents population growth; population will go extinct

Zone of stress

the range of a factor where population growth =s death; population is at risk of eradication

Coping mechanisms

strategies used by organisms to overcome abiotic factors (increase their optimal range)

Dormancy

state of reduced activity during periods of unfavorable environmental conditions

Migration

move temporarily to a more favorable environment

Acclimation

ability to adjust to abiotic factors over time

Metabolic strategies

organisms utilize 2 basic strategies when interacting with the nonliving environment, esp. temperature

Conformers

organisms that do not regulate their interior environment (change as their external environment changes)

Regulators

use energy to control internal conditions (maintain homeostasis despite changes in environment)

Population size

number of individual members of a species found in an ecosystem

Population density

measure of how crowded a population is; number of individuals per square unit of area

Population dispersion

spatial distribution of individuals in a population

Uniform dispersion

commonly seen in agriculture

Random dispersion

commonly seen in animals

Clumped dispersion

commonly seen in plants due to light/soil requirements; also seen in migrating herds of animals

Inflection point

point of greatest slope; population is growing fastest

Carrying capacity

total number of members of a species that can be supported by an ecosystem

Limiting factors

environmental factors that control the size of a population

Density dependent factors

shortage of food/space

Density independent factors

weather, floods, fire

Exponential growth is experienced by

bacteria

Niche

role of an organism within an ecosystem determined by its environment

Habitat

location where an organism lives

Generalists

species who can occupy a very broad niche; tolerates a wide range of conditions and uses a variety of resources

Specialists

species who occupy a very narrow niche

Producers

autotrophs (manufacture their own food via photosynthesis)

Consumers

heterotrophs (cannot manufacture their own food, must ingest other organisms)

Primary consumer (herbivore)

organisms that eat only producers

Secondary consumers

organisms that eat other consumers

Carnivore

eats only other consumers

Omnivore

will eat both producers & consumers

Scavenger

will eat organisms that have recently died

Tertiary consumer

must be a carnivore

Decomposers

organisms that break down dead organic tissues & organic matter

Food chain

sequence of energy transfer within an ecosystem beginning with a producer (single pathway of energy flow)

Food web

interlinked food chains; complex energy pathway

Trophic level

position of an organism within a food web (only 10% of energy is passed onto the next trophic level)

Ecological pyramid

diagram showing the changes in available energy, # of organisms, or biomass in an ecosystem

Biogeochemical cycles

movement of inorganic substances & elements through Earth’s air, water, and soil & through organisms

• water cycle

• carbon-oxygen cycle

• nitrogen cycle

Water cycle

• precipitation (to land)

• evaporation (from land)

• surface runoff

• transpiration (from vegetation)

• ground infiltration

Carbon-oxygen cycle

carbon fixation, photosynthesis

cellular respiration, combustion

decomposition, fossil fuels

(coal, oil, natural gas)

Nitrogen cycle (think bacteria!)

nitrogen fixation, denitrification

ammonification, assimilation

nitrifying bacteria, denitrifying bacteria

nitrification, nitrate

ammonia