Chapter 45: Population & Community Ecology – Definitions

Age structure

Proportion of individuals in different age groups in a population.

Aggressive display

Behavior meant to intimidate or deter competitors/predators.

Aposematic coloration

Bright warning colors indicating toxicity or danger.

Batesian mimicry

Harmless species mimics a harmful one.

Behavior

Any action performed by an organism.

Behavioral biology

Study of how organisms behave and why.

Birth rate (B)

Number of births per population per unit time.

Biotic potential (rmax)

Maximum rate a population can grow under ideal conditions.

Carrying capacity (K)

Maximum population an environment can sustainably support.

Camouflage

Blending with surroundings to avoid detection.

Classical conditioning

Learning by associating two stimuli (Pavlov).

Climax community

Stable, final community after succession.

Cognitive learning

Learning through thought, reasoning, or processing information.

Commensalism

One species benefits, the other is unaffected.

Competitive exclusion principle

Two species cannot occupy the same niche indefinitely.

Conditioned behavior

Behavior shaped by experiences (learning).

Courtship display

Behaviors used to attract mates.

Death rate (D)

Number of deaths per population per unit time.

Demographic-based population model

Predicts population using birth, death, immigration, age structure.

Demography

Study of population size, structure, birth/death rates.

Density-independent regulation

Population changes regardless of population size (storms, fires).

Density-dependent regulation

Regulation that depends on population size (competition, disease).

Distraction display

Behavior to distract predators from offspring (ex: feigning injury).

EmSleyan/Mertensian mimicry

Harmful species mimics a deadly one to avoid predators.

Energy budget

Allocation of energy to growth, maintenance, reproduction, etc.

Environmental disturbance

Event that changes an ecosystem (fires, floods).

Ethology

Scientific study of animal behavior.

Exponential growth

Rapid, unlimited population growth (J-shaped curve).

Fecundity

Number of offspring an organism can produce.

Fixed action pattern

Innate, unchangeable behavioral sequence triggered by stimulus.

Foraging

Searching for and obtaining food.

Foundation species

Species that shapes environment and creates habitat (ex: corals).

Habituation

Learning to stop responding to repeated, harmless stimuli.

Host

Organism that supports a parasite.

Imprinting

Rapid learning occurring early in life (ex: chicks following mother).

Innate behavior

Behavior an organism is born with.

Intersexual selection

Mate choice; one sex selects mates of the other.

Interspecific competition

Competition between different species.

Intrasexual selection

Competition between individuals of the same sex for mates.

Intraspecific competition

Competition among individuals of the same species.

Island biogeography

Study of species diversity on islands based on size/isolation.

Iteroparity

Reproducing multiple times throughout life.

J-shaped growth curve

Exponential population growth pattern.

K-selected species

Species with few offspring, long development, high parental care.

Keystone species

Species with a disproportionately strong effect on ecosystem.

Kinesis

Random movement response to stimulus intensity (no direction).

Learned behavior

Behavior modified by experience.

Life history

Traits affecting reproduction, survival, lifespan.

Life table

Summary of survival and reproduction for age groups.

Logistic growth

Growth slowed by limiting factors; forms S-shaped curve.

Migration

Seasonal movement from one location to another.

Monogamy

One male and one female form a pair bond.

Mortality rate

Number of deaths in a population per unit time.

Mutualism

Both species benefit.

Müllerian mimicry

Two harmful species resemble each other.

One-child policy

Government policy limiting families to one child (example of population control).

Operant conditioning

Learning based on rewards/punishments.

Parasite

Organism that lives on or inside a host, harming it.

Pioneer species

First species to colonize disturbed habitats.

Polyandry

One female mates with multiple males.

Polygyny

One male mates with multiple females.

Population density

Number of individuals per unit area.

Population growth rate

Change in population size over time.

Population size (N)

Total number of individuals in a population.

Primary succession

Ecological succession on new, barren land (no soil).

Quadrat

Square frame used for sampling sessile organisms.

r-selected species

Species with many offspring, little/no parental care, short lifespan.

Relative species abundance

Proportion of each species in a community.

Reflex action

Automatic, rapid response to a stimulus.

S-shaped growth curve

Logistic growth pattern.

Secondary succession

Succession after disturbance where soil remains.

Semelparity

Single reproductive event in life (ex: salmon).

Signal

Behavior or trait used to communicate.

Species dispersion pattern

How individuals are spaced (clumped, random, uniform).

Species richness

Number of different species in a community.

Survivorship curve

Graph showing survival rates across lifespan.

Symbiosis

Close relationship between two species.

Taxis

Directed movement toward/away from a stimulus (ex: toward light).

Zero population growth

Births + immigration = deaths + emigration (no growth).