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34 Cards in this Set
- Front
- Back
- 3rd side (hint)
Populations
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group of individuals of one species in one area at one time
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Density
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number of individuals per unit area/volume
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Dispersion
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spacing of individuals within a geographic area
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Clumped dispersion
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aggregated in patches’
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Uniform dispersal
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evenly spaced, sometimes caused by interaction between individuals
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Random
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unpredictable, no attraction or repulsion
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Additions to population size happen because?
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reproduction, immigration
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Populations decline because?
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death or emigration
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Survivorship curves
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plot of number in a cohort still alive at each age
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Type I survivorship curve
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flat at start then drops steeply (human)
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Type II survivorship curve
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constant death rate over lifetime (rodents
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Type III survivorship curve
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drops sharply on left side but flattens out at a certain age. Many young left on their own (fish, spiders)
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Life history
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traits that affect an organism’s schedule of reproduction and survival
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Big bang reproduction
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lots of babies then die (century plants, salmon) - semelparity
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Repeated reproduction
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reproduce annually, few young each time – iteroparity, lizards
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What is the sign for population size?
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N
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Change in population size formula
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birth-deaths
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R
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=per capita birth-per capita death
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R is positive if?
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population is growing
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R is negative if?
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population is declining
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R is 0 if?
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zero population growth, no change
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Carrying capacity
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K, maximum population size a particular environment can support at a given time
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Exponential growth
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ideal conditions constrained only by life history. No population can remain there indefinitely
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K selection
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density dependent, crowded environments, adoptions favor traits that help survival under crowded circumstances
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R selection
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density independent favors rapid reproduction traits
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Density dependent limiting
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death rates rise with the population
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Density independent
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birth/dates don’t change with density
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What are seven things that cause negative feedback?
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resource limitation, territoriality, availability of nesting sights, health of organisms, predation, accumulation of toxic waste. Disease
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None
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Boom-bust cycle
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fluctuations with regularity that can’t be explained by change alone
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Human population growth
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has been growing exponentially with 300 years but can’t do so forever
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Demographic transition
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moving from high birth and death to low birth and death
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How does demographic transition happen (5)
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some countries regulation birth rate (china), voluntary contraception, family planning, social change (women working), delayed reproduction
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Age structure
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relative number of individuals in each age
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Bottom line of reproduction
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it all depends on the survival rate of the offspring, if poor repeated reproduction is favored, if good big bang is favored
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