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Coombs - APES Chapter 8

STUDY
PLAY
immigration
organisms in a population moving into an area
emigration
organisms in a population moving out of an area
age structure
proportion of individuals in a population at various age ranges
pre-reproductive
individuals not capable of reproducing
reproductive
individuals capable of reproducing
post-reproductive
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
j-curve
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
s-curve
logistic growth, hovering slightly above and below the carrying capacity
overshoot
exceeding the carrying capacity
density-dependent population controls
Limiting factors have a greater effect as density increases
Mostly Biotic Factors
Competition for resources
Predation
Parasitism
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.