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organisms in a population moving into an area


organisms in a population moving out of an area

age structure

proportion of individuals in a population at various age ranges


individuals not capable of reproducing


individuals capable of reproducing


individuals too old to be capable of reproducing

intrinsic rate of increase (r)

how fast a population would grow under ideal conditions with no limiting factors or environmental resistance acting upon it

environmental resistance

any factor (limiting factor) that can limit a populations growth; ex: amount of space, temperature, precipitation, disease, food availability

biotic potential

capacity for growth; how well an organism can reproduce and get offspring out into the environment; ex: high biotic potential = fish, insects, small mammals like mice, etc.; low biotic potential = large mammals like the panda, elephants, rhinos, etc.

carrying capacity (K)

maximum number of individuals an ecosystem can support for an extended period of time or indefinitely; determined by biotic potential of the organism and the environmental resistance factors that population faces

exponential growth

rapid growth; doubling of population each generation; usually associated with intrinsic rate of increase (r); happens when organisms have very little environmental resistance factors or limiting factors acting upon them


exponential growth demonstrated by a population when it has few limiting factors or little environmental resistance acting upon it

logistic growth

rapid explosive growth followed by decrease in population growth until population levels off


logistic growth, hovering slightly above and below the carrying capacity


exceeding the carrying capacity

density-dependent population controls

Limiting factors have a greater effect as density increases
Mostly Biotic Factors
Competition for resources
Infectious disease

density-independent population controls

Limiting factor effects are not dependent on the size of the herd
Mostly Abiotic Factors
Weather/Climate Related
Natural Disasters

stable growth

population size fluctuates above and below carrying capacity
Ex: undisturbed tropical rain forest

irruptive growth

growth may explode, then crash
Ex: seasonal insects

cyclic growth

boom and bust cycles
Ex: lynx and snowshoe hare; wolf-moose interactions
Top-down population regulation
Bottom-up population regulation

irregular growth

no recurring pattern; often caused by catastrophic events like natural disasters or major habitat destruction that cannot be predicted

asexual reproduction

Offspring are exact genetic copies (clones) of a single parent
Examples: single-celled bacteria, corals, yeast, vegetative in plants

sexual reproduction

two organisms mix genetic material so offspring is a combination of both

r-selected species

reproduce quickly, high biotic potential, many offspring, little care to offspring; ex: insects (roaches), small mammals (mice, rats, rabbits), etc.

K-selected species

reproduce slowly, low biotic potential, few offspring, a lot of care to offspring; ex: large mammals like elephants, panda, kangaroo

late loss population survivorship curve

organisms in population live long life and often have few offspring but give offspring a lot of care; ex: large mammals

constant loss population survivorship curve

organisms die off evenly at all ages throughout lifespan; ex: song birds

early loss population survivorship curve

organisms in population die off at early ages, parents have many offspring but give little care to offspring; ex: fish, insects, etc.

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