Animal Ecology Final Book study (4/24/25)

Ecotone

A boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species.

Interdependent communities

Communities in which species depend on each other to exist.

Independent communities

Communities in which species do not depend on each other to exist

Species richness

The number of species in a community.

Log-normal distribution

A normal, or bell-shaped, distribution that a uses a logarithmic scale on the x axis.

Rank-abundance curve

A curve that plots the relative abundance of each species in a community in rank order from the most abundant species to the least abundant species.

Species evenness

A comparison of the relative abundance of each species in a community.

Keystone species

A species that substantially affects the structure of communities despite the fact that individuals of the species might not be particularly numerous.

Intermediate disturbance hypothesis

The hypothesis that more species are present in a community that occasionally experiences disturbances than in a community that experiences frequent or rare disturbances,

Food chain

A linear representation of how different species in a community feed on each other.

Food web

A complex and realistic representation of how species feed on each other in a community.

Trophic level

A level in a food chain or food web of an ecosystem.

Primary consumer

A species that eats producers.

Secondary consumer

A species that eats primary consumers.

Tertiary consumer

A species that eats secondary consumers

Omnivore

A species that feeds at several trophic levels.

Guild

Within a given trophic level, a group of species that feeds on similar items.

Direct effect

An interaction between two species that does not involve other species.

Indirect effect

An interaction between two species that involves one or more intermediate species.

Trophic cascade

Indirect effects in a community that are initiated by a predator.

Density-mediated indirect effect

An indirect effect caused by changes in the density of an intermediate species

Trait-mediated indirect effect

An indirect effect caused by changes in the traits of an intermediate species.

Bottom-up control

When the abundances of trophic groups in nature are determined by the amount of energy available from the producers in a community.

Top-down control

When the abundance of trophic groups is determined by the existence of predators at the top of the food web.

Succession

The process by which the species composition of a community changes over time.

Seral stage

Each stage of community change during the process of succession.

Pioneer species

The earliest species to arrive at a site.

Climax community

The final seral stage in the process of succession.

Chronosequence

A sequence of communities that exist over time at a given location.

Primary succession

The development of communities in habitats that are initially devoid of plants and organic soil, such as sand dunes, lava flows, and bare rock.

Secondary succession

The development of communities in habitats that have been disturbed and include no plants but still contain an organic soil.

Facilitation

A mechanism of succession in which the presence of one species increases the probability that a second species can become established.

Inhibition

A mechanism of succession in which one species decreases the probability that a second species will become established.

Priority effect

When the arrival of one species at a site affects the subsequent colonization of other species.

Tolerance

A mechanism of succession in which the probability that a species can become established depends on its dispersal ability and its ability to persist under the physical conditions of the environment.

Transient climax community

A climax community that is not persistent.

Community stability

The ability of a community to maintain a particular species composition.

Community resistance

The amount that a community changes when acted upon by some disturbance, such as the addition or removal of a species.

Community resilience

The ability of a community to return to its original state after being disturbed.

Alternative stable state

When a community is disturbed so much that the species composition and relative abundance of populations in the community change, and the new community structure is resistant to further change.

Fire-maintained climax community

A successional stage that persists as the final seral stage due to periodic fires.

Grazer-maintained climax community

When a successional stage persists as the final seral stage due to intense grazing

Primary productivity

The rate at which solar or chemical energy is captured and converted into chemical bonds by photosynthesis or chemosynthesis.

Standing crop

The biomass of producers present in a given area of an ecosystem at a particular moment in time.

Gross primary productivity (GPP)

The rate at which energy is captured and assimilated by producers in a given area.

Net primary productivity (NPP)

The rate at which energy is assimilated by producers and converted into producer biomass in a given area.

Remote sensing

A technique that measures conditions on Earth from a distant location, typically using satellites or airplanes that take photographs of large areas of the globe.

Green food web

A food web focused on how the producers obtain energy from photosynthesis (or chemosynthesis) and how this energy moves up the food web when producers are consumed.

Brown food web

A food web focused on how scavengers, detritivores, and decomposers obtain energy from dead organic matter and how this energy moves up the food web when they are consumed.

Egested energy

The portion of consumed energy that is excreted or regurgitated.

Assimilated energy

The portion of energy that a consumer digests and absorbs.

Respired energy

The portion of assimilated energy a consumer uses for respiration.

Net secondary productivity

The rate of consumer biomass accumulation in a given area.

Trophic pyramid

A chart composed of stacked rectangles representing the amount of energy or biomass in each trophic group.

Pyramid of energy

A trophic pyramid that displays the total energy existing at each trophic level.

Pyramid of biomass

A trophic pyramid that represents the standing crop of organisms present in different trophic groups.

Consumption efficiency

The percentage of energy or biomass in a trophic level that is consumed by the next higher trophic level.

Assimilation efficiency

The percentage of consumed energy that is assimilated.

Net production efficiency

The percentage of assimilated energy that is used for growth and reproduction.

Ecological efficiency

The percentage of net production from one trophic level compared to the next lower trophic level. AKA Food chain efficiency

Energy residence time

The length of time that energy remains in a given trophic level.

Biomass residence time

The length of time that biomass remains in a given trophic level.

Ecological stoichiometry

The study of the balance of nutrients in ecological interactions, such as between an herbivore and a plant.

Hydrologic cycle

The movement of water through ecosystems and atmosphere.

Nitrogen fixation

The process of converting atmospheric nitrogen into forms producers can use

Nitrification

The final process in the nitrogen cycle, in which ammonium is converted to nitrite (NO2-) and then nitrite is converted to nitrate (NO3-).

Mineralization

The process of breaking down organic compounds into inorganic compounds.

Denitrification

The process of converting nitrates into nitrogen gas.

Eutrophication

An increase in the productivity of aquatic ecosystems.

Cultural eutrophication

An increase in the productivity of aquatic ecosystems caused by human activities.

Weathering

The physical and chemical alteration of rock material near Earth's surface.

Watershed

An area of land that drains into a single stream or river.

Landscape ecology

The field of study that is focused on the spatial arrangement of habitats at different scales and how this influences individuals, populations, communities, and ecosystems.

Legacy effect

A long-lasting influence of historical processes on the current ecology of an area.

Local diversity

The number of species in a relatively small area of homogeneous habitat, such as a stream. Also known as Alpha diversity.

Regional diversity

The number of species in all the habitats that comprise a large geographic area. Also known as Gamma diversity.

Beta diversity

The number of species that differ in occurrence between two habitats.

Regional species pool

The collection of species that occurs within a region.

Species sorting

The process of sorting species in the regional pool among localities according to their adaptations and interactions,

Species-area curve

A graphical relationship in which increases in area (A) are associated with increases in the number of species (5),

Stepping stones

Small intervening habitat patches that dispersing organisms can use to move between large favorable habitats.

Species accumulation curve

A graph of the number of species observed in relation to the number of individuals sampled

Equilibrium theory of island biogeography

A theory stating that the number of species on an island reflects a balance between the colonization of new species and the extinction of existing species.

Potential evapotranspiration (PET)

The amount of water that could be evaporated from the soil and transpired by plants, given the average temperature and humidity.

Energy-diversity hypothesis

A hypothesis that states that sites with higher amounts of energy are able to support more species.

Continental drift

The movement of landmasses across the surface of Earth.

Pangaea

The single landmass that existed on Earth about 250 Mya and subsequently split into Laurasia and Gondwana.

Laurasia

The northern landmass that separated from Pangaea about 150 Mya and subsequently split into North America, Europe, and Asia.

Gondwana

The southern landmass that separated from Pangaea about 150 Mya and subsequently split into South America, Africa, Antarctica, Australia, and India.

Nearctic region

The biogeographic region of the Northern Hemisphere that roughly corresponds to North America.

Palearctic region

The biogeographic region of the Northern Hemisphere that corresponds to Eurasia.

Neotropical region

The biogeographic reign of the Southern Hemisphere that corresponds to South America.

Afrotropical region

The biogeographic region of the Southern Hemisphere that corresponds to most of Africa. Also known as Ethiopian region.

Indomalayan region

The biogeographic region of the Southern Hemisphere that corresponds to India and Southeast Asia. Also known as Oriental region.

Australasian region

The biogeographic region of the Southern Hemisphere that corresponds to Australia, New Zealand, and New Guinea.

Instrumental value of biodiversity

The economic value a species can provide.

Intrinsic value of biodiversity

A focus on the inherent value of a species not tied to any economic benefit.

Provisioning services

Benefits of biodiversity that humans use, including lumber, fur, meat, crops, water, and fiber.

Regulating services

Benefits of biodiversity that include climate regulation, flood control, and water purification.

Cultural services

Benefits of biodiversity that provide aesthetic, spiritual, or recreational value.