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34 Cards in this Set

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  • Back
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group of individuals of one species in one area at one time
number of individuals per unit area/volume
spacing of individuals within a geographic area
Clumped dispersion
aggregated in patches’
Uniform dispersal
evenly spaced, sometimes caused by interaction between individuals
unpredictable, no attraction or repulsion
Additions to population size happen because?
reproduction, immigration
Populations decline because?
death or emigration
Survivorship curves
plot of number in a cohort still alive at each age
Type I survivorship curve
flat at start then drops steeply (human)
Type II survivorship curve
constant death rate over lifetime (rodents
Type III survivorship curve
drops sharply on left side but flattens out at a certain age. Many young left on their own (fish, spiders)
Life history
traits that affect an organism’s schedule of reproduction and survival
Big bang reproduction
lots of babies then die (century plants, salmon) - semelparity
Repeated reproduction
reproduce annually, few young each time – iteroparity, lizards
What is the sign for population size?
Change in population size formula
=per capita birth-per capita death
R is positive if?
population is growing
R is negative if?
population is declining
R is 0 if?
zero population growth, no change
Carrying capacity
K, maximum population size a particular environment can support at a given time
Exponential growth
ideal conditions constrained only by life history. No population can remain there indefinitely
K selection
density dependent, crowded environments, adoptions favor traits that help survival under crowded circumstances
R selection
density independent favors rapid reproduction traits
Density dependent limiting
death rates rise with the population
Density independent
birth/dates don’t change with density
What are seven things that cause negative feedback?
resource limitation, territoriality, availability of nesting sights, health of organisms, predation, accumulation of toxic waste. Disease
Boom-bust cycle
fluctuations with regularity that can’t be explained by change alone
Human population growth
has been growing exponentially with 300 years but can’t do so forever
Demographic transition
moving from high birth and death to low birth and death
How does demographic transition happen (5)
some countries regulation birth rate (china), voluntary contraception, family planning, social change (women working), delayed reproduction
Age structure
relative number of individuals in each age
Bottom line of reproduction
it all depends on the survival rate of the offspring, if poor repeated reproduction is favored, if good big bang is favored