Coombs - APES Chapter 8

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.