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29 Cards in this Set
- Front
- Back
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(dN)
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Symbol representing change in population.
dN = natality - mortality |
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Life table:
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A summary of population size to analyze patterns of mortality as a function of age
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Cohort:
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a specific group within the population being studied
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Survival (lx)
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proportion of species living from the start of a life table to age x
lx = nx/n0 |
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dx
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The number of individuals dying during the age interval for x to x+1
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qx
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Mortality rate: per capita rate of mortality of x to x+1
qx = dx/nx |
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Raymond Pearl and his three patterns of mortality
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1. Low early in life, high later in life
2. Constant mortality across age 3. High early in life, low later in life draw 'dem fuckers |
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Static life table
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Doesn't use cohort, rather samples populations in several age groups.
Uses nx dx and qx. Beneficial because it's not always possible to follow an individual throughout its life. |
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Do cohort and static life tables give the same information?
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Only if determining conditions stay constant between comparing tables.
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Methods used to construct life tables:
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1. Direct observation of survivorship
2. Age at death observed 3. Direct observation of age structure to create a static life table |
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Natality schedule:
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describes the patterns of natality as a function of age in a population
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bx
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number of offspring produced per female of age x (natality rate)
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Net reproduction rate
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Number of daughters produced in the next generation, divided by the number of daughters produced in the current generation
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Stable Age Distribution Theory
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A population that is subject to a constant schedule of natality and mortality rates will gradually approach a fixed distribution and maintain this distribution indefinitely.
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Stable versus stationary age distributions
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• Stable age distribution occurs when a population is still growing geometrically.
• Stationary age distribution occurs when a population stops growing (mortality=natality). |
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Geometric Growth
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When a population inhabits a new landscape, their populations grow exponentially, or geometrically.
Little or no competition or disease. |
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Logistic Growth
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In most populations growth rate decreases as population increases.
Competition and disease and predation increase. |
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Discrete Generations:
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A female reproduces once and dies, a single generation exists.
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Overlapping Generations:
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A female can reproduce multiple times, so many generations can exist at once.
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Discrete Generation population growth formula:
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Nt+1 = R0 Nt
Nt = population size at generation t R0 = net reproductive rate, number of surviving offspring per generation per adult |
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Overlapping Generation population growth formula:
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Nt = R0^t N0
N0 = initial population size R0 = net reproductive rate Nt = population size at generation t |
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Geometric population growth formula:
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Nt+1 = R0Nt
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Density Dependence: two possible assumptions
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A. Constant reproduction rate
across population size B. Reproduction rate dependent on population size |
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Carrying Capacity:
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The maximum level a population reaches when resources become limiting
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Gause's Hypothesis:
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two species with a niche cannot live together in the same place indefinitely
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Types of Competition:
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Interspecies
Intraspecies Resource: compete for a limiting resource Interference: organisms seeking a resource harm one another in combat Apparent: produces a -/- effect, not really competition |
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Disease:
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An interaction where a disease organism lives on or within a host. Benefits the disease organism as is harmful to the host.
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Parasite:
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Similar to a disease, but contains multicellular organisms.
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Seroprevalence
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Percentage of organisms within a population with antibodies for a disease.
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