Topic Test 1: Ecology

Independent / Predictor variable

Factor that is not affected by another variable. Can be manipulated and is plotted on the x-axis.

Dependent / Response variable

Factor that changed based on the independent / predictor variable.

Discrete variable

Quantities that can only be a finite number of values.

Continuous variable

Quantities that can be a continuous range of values

Organisms

Individuals from the same species and their interactions with each other and the environment.

Populations

Groups made of one species that interact and live in the same area and time.

Species

An evolutionary unit.

Communities

Groups of species that interact and live in the same area and time.

Ecosystem

Includes abiotic and biotic factors of an environment.

Finite rate of increase

λ = N₁/N₀

Finite rate of increase over t years

N_t=N₀λ^t

Instantaneous rate of increase

N_t=e^rt

Exponential growth

Any pattern of increase when r or λ does not change over time.

Density dependent

Factors that influence a population based on its size.

Carrying capacity

The size of the population an environment can support long-term.

Ecology

The study of how organisms interact with each other and the environment.

Abiotic

The physical or non-living parts of an ecosystem.

Biotic

The living parts of an ecosystem.

Hypothesis

A proposed explanation for an observation.

Prediction

An outcome that should occur if the hypothesis is correct.

Null hypothesis

A hypothesis that represents the “no-effect” contrast to the hypothesis.

Treatment / Experimental group

The group undergoing experimental conditions.

Control group

A comparison, no-treatment group.

Controlled conditions

Factors used in both experimental / treatment and control groups to reduce bias and influence from confounding variables.

Outcome variable

The variable measured.

Niche

The range of abiotic and biotic factors a species lives in.

Fundamental niche

The possible range of conditions a species can tolerate.

Realized niche

The actual conditions a species is found in.

Evolutions

A change in allele frequencies across generations.

Adaptation

A change in allele frequencies that increase fitness in a population in an environment.

Ecosystem services

Goods and services provided to humans by the natural environment.

Humus

Soil organic matter originating in decaying plants roots, stems, and leaves.

Acclimation

A phenotypic change that helps an individual with a change in conditions.

Biomass

The total mass of living organisms in an area.

Disturbance

An event that removes biomass.

Habitat fragmentation

The conversion of large areas of native plant and animal communities to small fragments due to human development.

Keystone species

A species that has a very large impact on a community relative to its numbers.

Food web

A diagram showing trophic relationships among species in a community.

Trophic cascade

A change in the food web that causes change in an abundance of other species in the web.

Primary productivity

In most ecosystems, the amount of light energy captured by photosynthetic organisms.

Gross primary productivity

The total primary productivity in an area.

Net primary productivity (NPP)

The amount of primary productivity present in biomass.

Human appropriation of net primary productivity (HANPP)

The amount of primary productivity used by humans.

Trophic level

The level that certain species feed.

Sink

A long-term repository where a particular atom or molecule is located for an extremely long time.

Denitrification

A collection of metabolic processes in bacteria and archaea that release N₂. Analogous reactions release N₂ when biomass burns in wildfires.

Flux

The rate that a substance moves (direction and amount per unit time).

Dead zone

A region of oxygen-free water created by a chain of events that began from the over-fertilization of nitrogen.

Negative feedback

An event or process that decreases a process.

Positive feedback

An event or process that increases a process.

Phenology

The study of timing or seasonality of life events in organisms.

Phenological mismatch

Changes in phenology that change the way that two species interact.