Chapter 45: Population & Community Ecology – Definitions

A

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.

B

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.

C

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.

D

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).

E

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).

F

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).

H

Habituation – Learning to stop responding to repeated, harmless stimuli.

Host – Organism that supports a parasite.

I

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

J-shaped growth curve – Exponential population growth pattern.

K

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).

L

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.

M

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.

O

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

Operant conditioning – Learning based on rewards/punishments.

P

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).

Q

Quadrat – Square frame used for sampling sessile organisms.

R

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

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.

T

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

Z

Zero population growth – Births + immigration = deaths + emigration (no growth).