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49 Cards in this Set
- Front
- Back
What is the age structure of a population?
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the proportion of individuals in different age groups
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If an ecosystem has a carrying capacity of 1,000 individuals for a given species, and 2,000 individuals of that species are present, we can predict that the population
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size will decrease.
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Assume that there are five alligators per acre in a swamp in northern Florida. This is a measure of the alligator population's
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density.
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A tidal wave wipes out the entire population of mice living on an island. This is an example of
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the effects of abiotic factors on a population (density independent limiting factor).
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In a population of rabbits, which is the best example of a density dependent facto
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competition with other rabbits for shelter
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You drive through Iowa in the spring and notice that along a stretch of several kilometers, every third fence post has a male redwing blackbird perched on it defending its nesting territory. This is an example of
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uniform dispersion.
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Which of the following statements best describes features of a logistic growth curve
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The population grows exponentially at first (when resources are plentiful) but population growth levels off at the carrying capacity due density dependent factors, such intraspecific competition
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You have been studying a population of 200 shrews for one month. You record 50 shrew births and 10 shrew deaths in this time interval. What is the per capita rate of increase (r)?
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.2
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Which of the following refers to individuals of a single species that live in the same general area and can potentially interbreed
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Population
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A population that has a high level of parental care and high survivorship through the reproductive years likely has what type of survivorship curve?
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Type I
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Population Ecology is concerned with what?
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changes in population size and the factors that regulate populations over time.
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Population
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a group of individuals of a single species that occupy the same general area.
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Population Density
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The number of individuals of a species per unit area or volume
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Dispersion Pattern
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Dispersion Pattern of a population refers to the way individuals are spaced in their areas.
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Clumped Dispersion Pattern
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Grouped, most common in nature, results from unequal distribution of resources in environment, mating, or social behavior. Reduces predation and increases feeding efficiency.
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Uniform Dispersion Pattern
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evenly disbursed, often results from interactions between individuals of a population. Animals may exhibit uniform dispersion as a result of territorial behavior.
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Random Dispersion Pattern
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unpredictably spaced, without pattern. Varying habitat and social interactions make random dispersion rare.
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survivorship curves
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plot survivorships as the proportion of individuals from an initial population that are alive at each age.
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life tables
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track survivorship
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Describe the general type of work performed by population
ecologists. |
1. develop sustainable foods
2. assess the impact of human activities. 3. balance human needs with the conservation of bio-diversity and resources. |
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The larger the number of sample plots...
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the more accurate the estimates.
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Three characteristics of Individuals in a population are?
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– Rely on the same resources
– Are influenced by the same environmental factors – Are likely to interact and breed with one another |
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A population increases through...
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birth and immigration
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a population is decreased by...
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death and
emigration out of an area |
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Type I curve
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humans and other large mammals.
usually produce few offspring, give them good care, increasing the likelihood they will survive to adulthood. (Starts high and curves down) |
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Type II curve
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Intermediate, survivorship constant over the life span--no more vulnerable than any other point in life. Seen in invertebrates, lizards, rodents.(a straight line decreasing from left to right)
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Type III curve
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low survivorship for young, followed by a period when survivorship is high for individuals who live to a certain age. produce large number of offspring.
little to no care. Seen in invertebrates, oysters, perch. (a sloped L looking curve) |
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exponential population growth model
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{ G=rN } The rate of population increase under ideal conditions.
J-curve |
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logistic population growth model.
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{ G = rN * (K- N)/K }
a description of idealized population growth that is slowed by limiting factors as the population size increases. |
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r
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per-capita rate of increase (the average contribution of of each individual to population growth)
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G
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growth rate of the population ( # of individuals added per time interval)
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N
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the population size (number on individuals in population at a particular time)
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J-Curve
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exponential population growth model
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S-Curve
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logistic population growth model.
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limiting factors
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environmental factors that restrict population growth.
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Carrying capacity
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the maximum population size that a particular environment can sustain or carry.
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What are three factors that determine population size changes?
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1. competition among members of a population/density
2. physiological factors 3. abiotic factors/weather |
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Dynamics of many populations result from what?
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1. complex interaction of both density-dependent birth and death rates.
2. abiotic factors such as climate and disturbances. |
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If a population size is greater than the carrying capacity, what is predicted to happen?
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resources are finite and if the population size is greater than the carrying capacity the species die off until the population is at carrying capacity.
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Describe the factors that regulate growth in natural populations.
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Food and nutrient limitations, insufficient territories, increased disease, predation, accumulation of toxins.
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What are limiting factors?
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environmental factors that restrict population growth.
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What are density independent factors?
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seasonal changes: fires, floods, storms, habitat disruption by human activity, can affect a population size regardless of its density.
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What are density dependent factors?
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competition among members of a population. physiological factors. abiotic factors such as weather.
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Boom and bust cycles?
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booms are rapid exponentional growth and are followed by busts (when population levels fall back down to a minimal level)
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What is maximum sustained yield?
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harvesting should be done at a level that produces a consistent yield without forcing a population into decline. A population growing according to the logistic model increases the fastest when its density is at an intermediate level relative to its carrying capacity.
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Explain how the structure of the world’s human population has changed and continues to change.
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began as exponential growth, but is beginning to level out and is forecasted to drop back down over time.
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Describe the key factors that affect human population growth.
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?
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What is meant by the term demographic transition?
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a shift from zero population growth in which birth rates and death rates are high but roughly equal, to zero population growth characterized by low birth and death rates.
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What is meant by the term population momentum?
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In a population in which r=0, the continuation of a population growth as girls in the pre-reproductive age group reach their reproductive years.
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