Ecology Terms

Population

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.

Distribution

How individuals are distributed, or spread, throughout their habitat.

Abiotic

Non-living, referring to the physical and chemical properties of an environment.

Biotic

Living organisms withing an ecosystem.

Dispersal

The movement of individuals or gametes away from their parent location. This movement sometimes expands the geographic range of a population species.

Range

Spatial area where a species is found.

Microclimate

Climate patterns on a very fine scale, such as the specific climate conditions under a log.

Per Capita

Per capita population growth (r) depends on per capita birth (b), death (d) and net migration (m) rates.

Coniferous

Producing cones, and having leaves that do not fall off in the winter.

Deciduous

(of a tree or shrub) shedding its leaves annually.

Biome

Any of the world’s major ecosystem types, often classified according to the predominant vegetation for terrestrial biomes and the physical environment for aquatic biomes and characterized by adaptations of organisms to that particular environment.

Dispersion

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

Gregarization

Change from population of solitary forms to population of company loving forms.

Outbreak

Rapid increase in population abundance. Something allowed the population to grow rapidly.

Mark-recapture

A sampling technique used to estimate the size of animal populations.

Demography

The study of changes over time in the vital statistics of populations, especially birth and death rates.

Vital rates

Relative frequencies of vital occurrences that affect changes in the size and composition of a population (e.g., birth and death rates).

Cohort

A group of individuals of the same age in a population.

Trade-offs

More offspring=less energy put into each one (r strategist), with many being low quality (most do not survive). Few high quality offspring=each likely to survive (k strategist).

Fitness

Maximizing fitness-maximizing contribution to the gene pool of the next generation.

Semelparity

Reproduction in which an organism produces all of its offspring in a single event; also known as big-band reproduction.

Iteroparity

Reproduction in which adults produce offspring over many years; also known as repeated reproduction.

Carrying capacity

(k) The number of individuals that can be supported in a given environment.

Sigmoid

An s-shaped curve, representative of a growing population (N

Density-dependence

Referring to any characteristic that varies with population density (e.g., death rate).

Equilibrium

When birth rate (b)=death rate (d)

Regulation

Biological processes that counterbalance disruptive events.

Total fertility rate (TFR)

Number of children per female over her lifetime. Replacement TFR=2.1 children, where births exactly replace deaths.

Thermocline

Zone of rapid temperature change.

Pelagic

The open-water component of aquatic biomes

Benthic

The bottom surface of an aquatic environment

Photic

The narrow top layer of an ocean or lake where light penetrates sufficiently for photosynthesis to occur.

Aphotic

The part of an ocean or lake beneath the photic zone, where light does not penetrate sufficiently for photosynthesis to occur.

Neritic

The shallow region of the ocean overlying the continental shelf.

Limnetic

In a lake, the well-lit, open surface waters far from shore

Littoral

In a lake, the shallow, well-lit waters close to shore

Stratification

Zones of temperature and nutrient levels

Oligotrophic

Having a deficiency of plant nutrients that is usually accompanied by an abundance of dissolved oxygen.

Eutrophic

When the environment is enriched with nutrients, increasing the amount of plant and algae growth to estuaries and coastal waters. can be harmful to aquatic life.

Estuary

The area where a fresh water stream or ocean merges with the ocean

Barnacle

Arthropods that live in shallow tidal waters. Have free-swimming larvae.

Desiccation

The removal of moisture from something (stopped Balanus barnacles from moving further up-shore).

Niche

Realized niche- the ‘observed’ niche that an organism occupies in the world.

Fundamental niche- the conditions in which an organism can survive and reproduce.

Competitive exclusion

The concept that when populations of two similar species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population.

Macroalgae

Chlorophyll containing organisms composed of a group of cells arranged in colonies or as an organism.

Symbiosis

An ecological relationship between organisms of two different species that live together in direct and intimate contact.

Mutualism

An ecological interaction that benefits each of the interacting species.

Commensalism

A symbiotic relationship in which one organism benefits but the other is neither helped nor harmed.

Parasitism

A symbiotic relationship in which one organism, the parasite, benefits at the expense of another, the host, by living either within or on the host.

Zooxanthellae

Photosynthetic eukaryotes that live inside coral cells and produce carbohydrates and feed corals while getting CO2 and protection from the corals.

Herbivory

An interaction in which an organism eats parts of a plant or alga.

Species richness

Number of species. Structures a community.

Trophic

The different feeding relationships in an ecosystem, which determine the route of energy flow and the pattern of chemical cycling.

Food web/food chain

Food webs are made of food chains and represent the trophic interactions. (vertical) position in the food web is called a ‘trophic level.’

Dominant

Dominant species have a large impact due to high biomass. E.g., barnacles.

Keystone

Keystone species have a large impact despite low biomass and abundance. They are usually predators.

Ecosystem engineer

Large impact because the alter the physical environment. E.g., beavers.

Trophic cascade

Impacts of the top predators extends to lower trophic levels.

Top-down control

Higher trophic level reduces abundance or biomass of lower trophic level.

Bottom-up control

Lower trophic level controls abundance or biomass of higher trophic level.

Regime shift

Abrupt shift to a very different and persistent community. E.g., kept to urchin barrens.

Pathogen

An organism, virus, viroid, or prion that causes disease.

Transmission

Pathogens must move between hosts.

Direct-pathogens move from one host to the next.

Indirect-pathogens use another organism (vector) to help them move.

Vector

An organism that transmits pathogens from one host to another.

Host

The larger participant in a symbiotic relationship, often providing a home and food source for the smaller symbiont.

Migratory

Migratory birds move ticks to new locations.

Incidence

The total number of individuals in a population who have a disease or health condition at a specific period of time.

Phytoplankton

Photosynthesizing microscopic protists and bacteria that provide food for a wide range of organisms.

Krill

Small crustaceans that eat phytoplankton.

Ecosystem component

Living and non-living components that are connected organism-to-organism and organism-to-physical environment.

Autotroph

An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms. Autotrophs use energy from the sun or from oxidation of inorganic substances to make organic molecules from inorganic ones.

Heterotroph

An organism that obtains organic food molecules by eating other organisms or substances derived from them.

Detritus

Dead organisms. Decomposers obtain chemical energy and nutrients from detritus.

Radiant energy

Energy from the sun.

Photosynthesis

The conversion of light energy to chemical energy stored in sugars or other organic compounds.

Respiration

Ecosystems lose heat energy through respiration. CO2 is returned to the atmosphere.

Assimilation

The process in which living organisms integrate nutrients from various external resources to their body and utilizes them to satisfy the energy demands required to stay alive. NH4+→organic N, NO3- → Organic N

Gross primary production

Total light energy captured by plants

Net primary production

Plant growth rate (energy accumulated as biomass).

Net ecosystem production

Energy (biomass) accumulated in all ecosystem components (per unit time).

\-Plants capture energy

\-Energy stored as biomass in all components

\-Heat energy lost from all components

Limiting nutrient

Nitrogen. An element that must be added for production to increase in a particular area.

Protist

An informal term applies to any eukaryote that is not a plant, animal, or fungus. Most protists are unicellular, though some are colonial or multicellular.

Cyanobacteria

Bacteria that obtain energy via photosynthesis.

Biogeochemical

Any chemical cycle that involves both biotic and abiotic factors.

Nitrate

Created in the second step of the bacteria driven Nitrogen cycle-Nitrification (NH4+→NO3-).

Ammonium

Created in the first step of the bacteria driven nitrogen cycle -N-fixation (N2→NH4+).

Nitrification

NH4+→NO3-

Denitrification

NO3-→N2

Nitrogen-fixation

N2→NH4+

Legume

Agriculture increases rates of N-fixation by growing legumes.

Leaching

Excess water removes water-soluble nutrients out of soil, by runoff or by drainage.

Cation

A positively charged ion

Eutrophication

Excessive primary production (growth) due to overload of nutrients.

Dead zone

Decomposition of algae leads to O2 depletion, low O2=fish and others die.

Nitrogen-deposition

Increased through fossil fuel use. The input of reactive nitrogen from the atmosphere to the biosphere.

Natural selection

Those with more appropriate behaviour pass on more genes and are more likely to survive and produce offspring.

Altruism

Selflessness; behaviour that reduces an individual’s fitness while increasing the fitness of another individual. E.g., the Pika call.

Fitness

Behaviour should have a fitness advantage. Altruism doesn’t follow this law.

Kin selection

Selection for an act that enhances relative’s reproductive success.

Relatedness

Shared genes (r) (C