Sci 112 Chapter 7 Populations: Characteristics And Issues

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Population

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a group of individuals of the same species occupying a given area.

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Natality

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the number of individuals added to the population through reproduction.

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Birthrate

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the number of individuals born per thousand individulas in the population per year.

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Mortality

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the number of deaths per year.

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Death Rate

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the number of deaths per thousand individuals in the population per year.

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Survivorship Curve

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a graph that shows the proportion of individuals likely to survive to each age.

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Population Growth Rate

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the rate at which additional individuals are added o the population; the birthrate minus the death rate.

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Sex Ratio

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comparison between the number of males and females in a population.

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Age Distribution

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the comparative percentages of different age groups within a population.

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Population Density

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a measure of how close organisms are to one another, generally expressed as the number of organisms per unit area.

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Dispersal

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migration of organisms from a concentrated population into areas with lower population densities.

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Emigration

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movement out of an area that was once one's place of residence.

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Immigration

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movement into an area where one has not previously resided.

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Lag Phase

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the initial stage of population growth during which growth occurs very slowly.

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Exponential Growth Phase (log phase)

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the period during population growth when the population increases at an ever-increasing rate.

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Deceleration Phase

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a part of the population growth curve in which the rate of population increase begins to decline.

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Stable Equilibrium Phase

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the phase in a population growth curve in which the death rate and birthrate become equal.

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Limiting Factors

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the primary condition of the environment that determines the population size for an organism.

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Environmental Resistance

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the combination of all environmental influences that tend to keep population stable.

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Extrinsic Limiting Factors

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factors that limit population size and that come from outside the population.

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Intrinsic Limiting Factors

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factors that limit population size that come from within the population.

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Density-Dependent Limiting Factors

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those limiting factors that become more severe as the size of the population increases.

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Density-Independent Limiting Factors

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those limiting facotrs that are not affected by population size.

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Death Phase

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the portion of the population growth curve of some organisms that shows the population declining.

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Carrying Capacity

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the optimum number of individuals of a species that can be supported in an area over an extended period of time.

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K-Strategists

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large organisms that have relatively long lives, produce few offspring, provide care ofr their offspring, and tpically have populations that stabilize at the carrying capacity.

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R-Strategists

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typically, a small organism that has a short life span, produces a large number of offspring, and does not reach a carrying capacity.

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More-Developed Countries

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countries of the world that typically have a per capita income that exceeds US $10,000; Europe, Canada, United States, Australia, New Zealand, and Japan

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Less-Developed Countries

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countries of the world that typically have a per capita income of less than US %5,000.

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Population Density

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a measure of how close organisms are to one another, generally expressed as the number of organisms per unit area.

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Ecological Footprint

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the area of the Earth's productive land and water required to supply the resources that an individual demands as well as to absorb the wastes that the individual produces.

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Demography

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the study of human populations, their characteristics, adn their changes.

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Total Fertility Rate

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the number of children born per woman per lifetime.

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Replacement Fertility

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the number of children per woman needed just to replace the parents.

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Zero Population Growth

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the stabilized growth stage of human population during which births equal deaths and equilibrium is reached.

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Age Distribution

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the comparative percentages of different age groups within a population.

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Standard of Living

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the necessities and luxuries essential to a level of existence that is customary within a society.

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Gross National Income

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an index that measures the total goods and services generated within a country as well as income earned by citizens of the country who are living in other countries.

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Demographic Transition

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the hypothesisthat economics proceed through a series of stages, beginning with growing population with high birth and death rates and low economic development and ending with stable populations with low birth and death rates and high economic development.

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Postwar Baby Boom

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baby boomers were born durin gan approximately 15-year period following World War II, constituting a bulge in the age distribution profile.