Unit 6 Ecology Study Guide
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Behavioral ecology: study of interaction between animals and their environments.
Ethology: study of animal behavior
Imprinting: innate behavior learned during critical period early in life (baby ducks imprint to mama ducks)
Migration: cyclic movement of animals over long distances according to the time of year.
Taxis: reflex movement toward or away from a stimulus
Coefficient of relatedness: statistic that represents the average proportion of genes two individuals have in
common. The higher the value, the more likely they are to help one another.
Chemical: communication through the use of chemical signals, such as pheromones
Visual: communication through the use of visual cues, such as the tail feather displays of peacocks
Auditory: communication through the use of sound, such as the chirping of frogs in the summer
Population: collection of individuals of the same species living in the same geographic area
Community: collection of populations of species in a geographic area
Ecosystem: community + environment
Biosphere: communities + ecosystems of the planet
Biotic components: living organisms of ecosystem
Abiotic components: nonliving players in ecosystem
Dispersion patterns:
o Clumped dispersion: animals live in packs spaced from each other (e.g. cattle)
o Uniform distribution: species are evenly spaced out across an area (e.g. birds on a wire)
o Random distribution: species are randomly distributed across an area,( e.g. trees in a forest)
Biotic potential: maximum growth rate for a population
Carrying capacity: maximum number of individuals that a population can sustain in a given environment
Limiting factors: factors that keep population size in check
o Density dependent (food, waste, disease)
o Density independent (weather, natural disasters)
Population growth
o Exponential growth (J shaped curve, unlimited growth)
o Logistic growth (S shaped curve, limited growth)
Life history strategies:
o K-selected populations (constant population size or growth, low reproductive rate, extensive parental
care – kangaroos)
o R-selected population (rapid population growth, J curve style, little parental care, quick reproduction,
high death rate – roaches)
Survivorship curves: show survival rates for different-aged members of a population
o Type I: live long life, until age is reached where death rate increases rapidly – humans, large mammals
o Type II: constant death rate across the age spectrum – lizards, small mammals
o Type III: steep downward death rate for young individuals that flattens out at certain age – fish, oysters,
sea turtles
Parasitism: one organism benefits at another’s expense (ticks and humans)
Commensalism: one organism benefits while the other is unaffected (clownfish and anemones)
Mutualism: both organisms benefit from the interaction (acacia trees and ants)
Competition: both species are harmed by the interaction
Predation: one species, the predator, hunts the other, the prey
Primary succession: occurs in area devoid of life that contains no soil
o Pioneer species come in, add nutrients, and are replaced by future species which attract animals to the
area, thus adding more nutrients
o Constant changing until the climax community is reached and a steady-state equilibrium is achieved
Secondary succession: occurs in area that once had stable life but was disturbed by major force (fire)
Trophic levels: hierarchy of energy levels on a planet; energy level decreases from bottom to top; primary
producers (bottom)  primary consumers (herbivores)  secondary consumers  tertiary consumers 
decomposers