AP Biology- Unit 8

Ecology

The scientific study of the interactions between organisms and the environment

Population ecology

Considers factors affecting population size over time

Community ecology

Considers the whole array of interacting species in a community

Ecosystems ecology

Emphasizes energy flow and chemical cycling among the various biotic and abiotic components of the environment

Global ecology

Concerned with the biosphere, or global ecosystem, which is the sum of all the planet’s ecosystems

Abiotic

Factors are the nonliving chemical and physical attributes of the environment

Biotic

Factors are the other organisms that make up the living component of the environment

Biomes

Major life zones characterized by
vegetation type or physical
environment

Climograph

Plots the annual mean temperature and precipitation in a region

Photic zone

Has sufficient light for photosynthesis

Aphotic zone

Receives little light

Pelagic zone

The photic and aphotic zones together

Benthic zone

The organic and inorganic sediment at the bottom of the pelagic zone

Benthos

The communities of organisms in the benthic zone

Littoral zone

Includes waters close to shore that are shallow enough for rooted plants

Limnetic zone

Includes waters farther from shores that are too deep to support rooted plants

Dispersal

The movement of individuals away from centers of high population density or from their area of origin

Biotic factors

Predation, herbivory, mutualism, parasitism, and competition

Abiotic factors

Temperature, water and oxygen, salinity, sunlight, and rocks and soil

Temperature

Limits the distribution of organisms
because of its effect on biological processes

Salinity

Salt concentration affects the water balance of organisms through osmosis

Sunlight

The energy source for photosynthetic organisms and, as such, can limit their distribution

Rocks and soil

Limits the distribution of organisms through their effects on the pH, mineral composition and physical structure of the substrate

Density

The number of individuals per unit area or volume

Dispersion

The pattern of spacing among individuals within the boundaries of the population

Immigration

The influx of new individuals from other areas

Emigration

The movement of individuals out of a population

Life table

An age-specific summary of the survival pattern of a population

Suvivorship curves

A graphic way of representing the data in a life table

Type I

High survivorship during early and middle life
followed by a steep drop due to increase in death rates among older age groups

Type II

Survivorship declines linearly due to a constant death rate over the organism’s life span

Type III

Low survivorship due to high death rates for
young age-groups and stable survivorship later in life
due to a lower death rate for survivors

Exponential population growth

Population increase under idealized conditions (food is abundant and all individuals reproduce at
physiological capacity)

Carrying capacity

(K) is the maximum population size the environment can support

Interspecific intereactions

Relationships between species in a community

Interspecific compeition

(−/− interaction) occurs when species compete for a resource that limits their growth or survival

Compeitive exclusion

Local elimination of a competing species

Ecological niche

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

Character displacement

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

Explotation

(+/– interaction) in which one species benefits by feeding on the other while the other species is harmed

Predatation

(+/– interaction) refers to an interaction
in which one species, the predator, kills and eats the
other, the prey

Cryptic coloration

Makes prey difficult to spot

Aposematic coloration

Animals with effective chemical defenses often
exhibit bright warning coloration

Batesian mimicry

A palatable or harmless species mimics an unpalatable or harmful model

Herbivory

(+/– interaction) refers to an interaction
in which an herbivore eats parts of a plant or alga

Parasitism

(+/– interaction) one organism, the
parasite, derives nourishment from another
organism, its host, which is harmed in the process

Positive intereactions

Any +/+ or +/0 interaction in which at least one species benefits and neither is harmed

Mutualism

(+/+ interaction) an interspecific interaction that benefits both species

Commensalism

(+/0 interaction) one species benefits and the other is neither harmed nor helped

Species diversity

The variety of organisms that make up the community

Species richness

The number of different species in the communit

Relative abudance

The proportion each species represents of all individuals in the community

Biomass

The total mass of all organisms in a habitat

Invasive species

Organisms that become established outside their native range

Trophic structure

To the feeding relationships between organisms in a community

Food chains

Link trophic levels from producers to top carnivores

Food web

Branching food chain with complex trophic interactions

Dominant species

Those that are most abundant or have the highest biomass

Keystone species

Strong control on a community by their ecological roles, or niches

Ecosystem engineers

Cause physical changes in the environment that affect community structure

Bottom-up model

Community organization proposes a unidirectional influence from lower to higher trophic levels

Top-down model

The trophic cascade model proposes that predation controls community organization

Biominupulation

An application of the top-down model used to improve water quality in 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 squence

The sequence of change in community composition after a disturbance

Primary succession

Occurs in nearly lifeless areas where there is no soil when succession begins

Secondary succession

Begins in an area where soil remains after a disturbance

Ecosystem

Consists of all the organisms living in a community, as well as the abiotic factors with which they interact

Law of conservation of mass

States that matter cannot be created or destroyed

Primary producers

Authrophs

Primary consumers

Herbivores

Secondary consumers

Carnivores

Tertiary consumers

Carnivores that feed on other carnivores

Detritivores/Decomposers

Consumers that derive their energy from detritus,
nonliving organic matter

Primary production

The amount of light energy converted to chemical
energy by autotrophs during a given time period

Gross primary production

Total primary production is known as the ecosystem’s

Limiting nutrient

The element that must be added for production to increase in an area

Eutrophication

The addition of large amounts of nutrients to lakes causes

Secondary production

The amount of chemical energy in food converted to
new biomass during a given period of time

Production efficiency

The fraction of energy stored in food that is used for secondary production

Trophic effieceny

The percentage of production transferred from one trophic level to the next is, on average, about 10%

Biogeochemical cycles

Involve both biotic and abiotic components

Bioremediation

The use of organisms to detoxify ecosystems

Biological augmentation

Uses organisms to add essential materials to a degraded ecosystem