Ecology Unit 1

Prezygotic

Barriers acting before fertilization.

Climate

Long-term prevailing weather patterns in an area.

Ecosystem

A biological community and its physical environment interacting.

Biosphere

The global ecosystem encompassing all life and Earth's environments.

Abiotic

Non-living chemical and physical factors in an environment.

Biotic

Living components of an ecosystem.

Climograph

A plot of temperature and precipitation for a region.

Disturbance

An event changing a community by removing organisms or altering resources.

Biome

Major life zones characterized by vegetation type or physical environment.

Photic zone

The upper water layer with sufficient light for photosynthesis.

Aphotic zone

The deep water layer receiving little or no sunlight.

Pelagic zone

The open-water component of aquatic biomes.

Thermocline

A narrow stratum of rapid temperature change in a body of water.

Benthos

The communities of organisms living at the bottom of an aquatic zone.

Littoral zone

The shallow, well-lit coastal waters of a lake or ocean.

Limnetic zone

The well-lit, open-water area of a lake inhabited by phytoplankton.

Benthic zone

The bottom surface of an aquatic environment.

Population density

The number of individuals per unit area or volume.

Immigration

The influx of new individuals into a population from other areas.

Species distribution

The spatial arrangement of species within an area.

Demography

The study of vital statistics of populations and how they change.

Life table

An age-specific summary of the survival rates of a population cohort.

Emigration

The movement of individuals out of a population.

Exponential growth

Population growth is unhindered by the abundance of resources available to an ever-increasing population.

Logistic growth

Population growth that slows as it nears carrying capacity.

Intrinsic rate of increase

Per capita growth rate of a population under ideal conditions.

Survivorship curve

A plot of the proportion or numbers in a cohort still alive at each age.

K-selection

Selection for life history traits sensitive to population density.

r-selection

Selection for life history traits maximizing reproductive success.

Density dependent

Factors whose impact varies with population density.

Carrying capacity

The maximum population size an environment can support.

Estuary

A habitat in which the freshwater of a river meets the saltwater of the ocean.

Trade-off

Compromises between competing life-history traits.

Negative feedback

A mechanism where a change triggers a response countering the change.

Density independent

Factors affecting population size regardless of density.

Interspecific

Interactions between different species.

Intraspecific

Interactions between members of the same species.

Competitive exclusion

The concept that competing species with identical niches cannot coexist.

Niche

An organism's ecological role and use of resources in its environment.

Resource partitioning

When species divide a niche to avoid/reduce competition for resources

Exploitation

An interaction where one organism benefits by feeding on another.

Predation

An interaction where one species kills and eats another.

Predator/prey

The consumer and consumed in an interaction.

Parasitism

A relationship in which one organism lives on or in a host, benefiting while harming it.

Mutualism

An interspecific interaction that benefits both species.

Commensalism

An interaction benefiting one species while the other is unaffected.

Herbivory

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

Relative abundance

The proportion each species represents of all community individuals.

Trophic structure

Feeding relationships among organisms in a community.

Food chain/web

The pathway or network of food transfer through trophic levels.

Equinox

Days when day and night are of approximately equal length.

Keystone species

A species exerting strong control on community structure relative to abundance.

Trophic level

The position an organism occupies in a food chain.

Ecosystem engineer

An organism that influences community structure by causing physical changes in the environment.

Solstice

The two days of the year on which the sun reaches its greatest distance north or south of the equator

Foundation species

A species with strong community effects due to size or abundance.

Leeward

The side of a mountain range that faces away from the oncoming wind.

Selective pressure

Any environmental factor reducing reproductive success in a population.

Nonequilibrium mode

A view of communities as constantly changing after disturbances.

Shannon/Simpson Index

An index of community diversity accounting for richness and relative abundance.

Intermediate disturbance hypothesis

The concept that moderate disturbance fosters greater species diversity.

Post-zygotic

Barriers acting after fertilization to prevent viable, fertile offspring.

Morphological species concept

Characterizes a species by body shape and other structural features.

Biological species concept

Defines a species as a group whose members can interbreed and produce viable, fertile offspring.

Phylogenetic species concept

Defines a species as the smallest group of individuals sharing a common ancestor on a phylogenetic tree as supported by DNA evidence

Behavioral species concept

Defines species based on behavioral differences, such as unique mating rituals.

Type I survivorship curve

A curve showing low death rates during early and middle life and a steep increase in older age groups.

Type II survivorship curve

A curve showing a constant death rate over an organism's life span.

Type III survivorship curve

A curve showing high death rates for the young followed by a flat rate for those that survive.