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39 Cards in this Set
- Front
- Back
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Exponential Growth `
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Growth at a constant rate per unit time. (2^x). Also called the geometric rate. Looks like a J and is sometimes called unfettered growth. This is the ideal!
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Rule of 70
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Predicts population doubling times by dividing the growth percentage into 70. (70/35=2)
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Arithmetic Growth
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Less than ideal environmental conditions produces a growth rate that is a constant fraction added to the original population. Produces a straight line graphically that never really happen.s. The straight line is the carrying capacity. (k)
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Biotic Potential
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The maximum reproduction rate for an organism and is based on the organism's ability to reproduce.
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In Vitro
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Populations have no limits
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In situ
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populations have limits.
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Negative growth rates
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occurs when the population exceeds the carrying capacity for the habitat.
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Carrying capacity
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the maximum number of organisms a habitat can have at any given time period.
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Dieback
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Negative growth rates
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Overshoot
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Small population growth above the carrying capacity.
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Population explosion/crash
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What a large positive/negative population growth rate is called.
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Malthusian (Irruptive) Growth
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when the is a population explosion followed by a crash.
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Environmental Conditions (5)
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Food, Shelter, Water, Nesting Site, Space
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Genetic Factors
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As the environmental conditions change, either aggression or reproduction rate dominates.
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Logistic Growth Model
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Growth to a Stable Population. Also called a sigmoid curve that looks like an "s" graphically.
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Chaotic Growth Curves
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populations that don't follow linear growth curves. Exhibit variability. Can be predicted over a long period of time.
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Catastrophe Theory
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Hypothetical theory used by biologists to explain population dynamics to show abrupt discontinuities. Cannot be predicted over a long period of time.
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R-Selected Strategies (Reproduction)
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Animals in lower trophic levels follow Malthusian Growth. They use large numbers to offset predation. There is little investment to the individual and growth is extrinsically controlled.
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K -Selected Strategies (Reproduction)
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Logistic Strategy are followed by animals higher up the tropic level. Intrinsically controlled growth for larger organisms that live longer and mature slower.
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Natality
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The production of new individuals.
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Fecundity
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the physical ability to to reproduce. (Human= 1 per year)
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Fertility
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the number of offspring produced.
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Immigration
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Introduced organisms into a new habitat or community. Seeds, spores, boats, winds, etc. Increases growth rate.
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Mortality
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the ability to die. Death rate. Number of living divided by the number of deaths in a given amount of time.
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Survivorship
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the percent of the population that survives to the next year. Most important to scientists.
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Cohorts
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all of the individuals born in a specific generation.
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Life expectancy
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the probable number of years an individual will survive.
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Life span
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the maximum number of years a person can survive.
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Type A Survivorship Pattern
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Full life expectancy, low death rates in pre-reproductive and reproductive stages, higher death rate in post-reproductive stage, k-selected reproduction,
Bears, whales, humans, elephants. |
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Type B Survivorship Pattern
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Death rate is unrelated to age, k selected reproduction, constant over life span
Ex: seagulls |
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Type C Survivorship Pattern
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High mortality rates in pre-reproductive period. Once they reach reprocution, suvival rate is very high until post reproduction. R-selected strategy.
Ex: song birds, deer, rabbits. |
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Type D Survivorship Pattern
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Very high mortality in early life, low mortality in next two stages. R selected reproduction.
Ex: Crustacean, fish, plants. |
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Age Structure Diagrams
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Combines mortality and natality.
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Population Momentum
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Dependent on the number of individuals in the pre-reproductive stage. Just compare to reproductive growth to determine direction of growth.
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Emigration
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The movement of individuals out of a population permanently.
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Migration
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Temporary emigration.
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Growth Rate Formula
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PG(R) = (BR+I) - (D+E)
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Biotic Regulators
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Tend to be density dependent.
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Abiotic Regulators
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Tend to be density independent.
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