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30 Cards in this Set
- Front
- Back
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True/ False:
The environment functions to limit population growth |
true.
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Please write out the logistic model of population growth.
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dN/dt=rN(1-N/K)
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What does population regulation involve?
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density dependence
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As resources become less available to an increasing number of indiviuals, what happens to mortality and population growth?
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Mortality Increases
Population Growth Decreases |
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What happens to mortality and growth rate when population begins to decline?
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Mortality rates Decrease
Birth Rates Increase Population Growth Speeds Up |
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What kind of regulation system is in control to regulate the population?
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Positive
Negative Feedback Systems |
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How does density dependent effect influence a population?
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It influences it in proportion to its size.
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How does density independent effects (bad weather conditions for example) influence a population?
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It will influence it regardless to the number of individuals.
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When does competition among species occur?
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when resources are limited
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Define competition.
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A pattern that results when individuals use a common resource that is in short supply relative to the number seeking it.
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How is intra-specofic competition different from competition? What are the (4) sub categories of competition?
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This is competition that occurs between individuals of the same speices.
(1)Scramble Comp. (2) Contest Competition. (3) Exploitation Comp. (4) Interference Competition |
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What is Scrambled Competition?
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When growth and reproduction are depressed equally across individuals in a population as the intensity of competition increases.
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What is contest competition?
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When some individuals claim enough resources while denying others a share.
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What is exploitation competition?
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Competing individuals dont interact directly, but use the resource (zebras eating grass;plants using up the water)
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What is Interference competition?
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Competing individuals interact directly, denying access to the resource (territory defense)
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What does intraspecific competition affect? Long-term what does it begin to affect?
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Growth and Development
Long-term it will begin to affect survival and reproduction |
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What is self-thinning?
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When the density in the population decreases, the biomass (weight) of the remaining individuals increases.
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What is the pattern discussed in reference to harp seals and density dependent effects?
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sexual maturity is more related to weight than age. the denser the population, the slower females are to gain weight and thus reach sexual maturity.
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Is fertitlity density dependent?
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yes, as the density population increase, the female reproduction rate decreases
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Give two examples of density dependent effects on fertility in plants.
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(1) Corn Plants: Grain (seed) production of indiv. corn plants declines with increasing density with increasing density of plants per acre.
(2) Salicornia (glasswort): Number of seeds produced per plant declines with increasing population density. |
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What kinds of high-density problems can result as a direct result of the stress it puts on populations.
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(1) delayed reproduction
(2) abnormal behavior (3) reduced ability to resist disease and parasite infections |
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Can dispersal be density dependent? if yes, explain.
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This is a constant phenomenon. It does not function directly as a mechanism of population regulation in the response to the over-exploitation of resources or crowding.
Example: Lemmings do not fling themselves into the ocean to make space for other lemmings. |
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When can dispersal be considered as density dependent?
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If dispersal increases as population increase.
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How can social behavior influence populations?
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It can function to limit or control the population. Example is wolf packs which are social groups tht have heierichies. The alpha male and female are only allowed to reproduce but everyone helps rear. The size is related to the availability of food. Decrease in food means indiviuals dispersing.
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Can territory function to regulate population?
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yes. A territory is an area that animal defends. the result of defended territories is a regular pattern of distribution.
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What is a homerange?
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The area that an animal normally uses during a year. In mammals:
- large animals have larger homeranges -carnivores have longer homeranges that omnivores or hebivores -males have larger homeranger than females or juvies. |
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What is the Johns Krebs Experiment?
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6 pairs of great tits removed from woodland territories. within a week, 4 new pairs moved into the woodland and established territory. The new pairs had previously been nesting in inferior habitats like hedgerows.
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Density- Independent Factors
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(1) precipitation
(2) floods and drought (3) temperature extremems (4)fire ---they can influence with no regards to population density |
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What does the Merriams kangaroo rat depend on?.
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reproduction depends on adequate winter rains to provide sufficient food. This is density-independent
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How is the white-tailed deer living in Minnesota affected by density-independent factors?
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the average number of fawns produced decreases with the amount of snow. THEREFOre
the annual change in population is inversely related to the previous winters snow accumulation. |
