Population biology

Population biology is the study of populations of organisms, especially the regulation of population size, life history traits such as clutch size, and extinction. The term population biology is often used interchangeably with population ecology, although 'population biology' is more frequently used when studying diseases, viruses, and microbes, and 'population ecology' is used more frequently when studying plants and animals.

Although Malthus's book, An Essay on the Principle of Population, dealt only with the economy of human population fluctuations, which he theorized as being related to finite food resources, abundance and decadence, it gave inspiration to Charles Darwin for the theoretical basis of his seminal work, The Origin of Species.

“

In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long- continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work; but I was so anxious to avoid prejudice, that I determined not for some time to write even the briefest sketch of it. In June 1842 I first allowed myself the satisfaction of writing a very brief abstract of my theory in pencil in 35 pages; and this was enlarged during the summer of 1844 into one of 230 pages, which I had fairly copied out and still possess.

”

Charles Darwin in his autobiography (written 1876, edited by his son and published 1887), pp. 34–35.

The Population Extra

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Hierarchy of life

Biosphere > Ecosystem > Biocoenosis > Population > Organism > Organ system > Organ > Tissue > Cell > Organelle > Biomolecular complex > Macromolecule > Biomolecule

Human impact on the environment

General	Anthropocene Environmental issues Human impact Impact assessment List of issues Planetary boundaries

Causes	Agriculture fishing irrigation meat production palm oil Energy industry biodiesel coal electricity generation nuclear power oil shale petroleum reservoirs wind power Manufacturing cleaning agents concrete nanotechnology paint paper pesticides pharmaceuticals and personal care Transport aviation roads shipping Other land use mining genetic pollution human overpopulation overexploitation particulates pollution war

Effects	Biodiversity threats Climate change Deforestation Desertification Ecocide Erosion Coral reefs Freshwater cycle Global warming Habitat destruction Holocene extinction Nitrogen cycle Land degradation Phosphorus cycle Ocean acidification Ozone depletion Runaway climate change

Mitigation	Birth control Cleaner production Climate change mitigation Climate engineering Ecological engineering Environmental engineering Environmental mitigation Industrial ecology Mitigation banking Organic farming Reforestation urban Restoration ecology Sustainable consumption Waste minimization

Commons Category by country assessment mitigation

Human/World population

Major topics	Biocapacity Optimum population Overpopulation Malthusian catastrophe Population Population ethics Population momentum Sustainable development Women's reproductive rights Zero population growth

Biological and related topics	Family planning Pledge two or fewer Human population control One-child policy Two-child policy Population biology Population decline Population density Physiological density Population dynamics Population growth Population model Population pyramid Projections of population growth

Human impact on the environment	Deforestation Desalination Desertification Environmental impact of agriculture of aviation of biodiesel of concrete of electricity generation of the energy industry of fishing of irrigation of mining of off-roading of oil shale industry of palm oil of paper of the petroleum industry of reservoirs of shipping of war Industrialisation Land degradation Land reclamation Overconsumption Pollution Quarrying Urbanization Loss of green belts Urban sprawl Waste Water scarcity Overdrafting

Population ecology	Carrying capacity Deep ecology Earth's energy budget Food security Habitat destruction I = P × A × T Malthusian growth model Overshoot (population) World energy consumption World energy resources World3 model

Literature	A Modest Proposal An Essay on the Principle of Population How Much Land Does a Man Need? Operating Manual for Spaceship Earth Population Control: Real Costs, Illusory Benefits The Limits to Growth The Population Bomb The Skeptical Environmentalist The Ultimate Resource

Publications	Population and Environment Population and Development Review Population and housing censuses by country

Lists	Metropolitan areas by population World population milestones

Events and organizations	7 Billion Actions International Conference on Population and Development Population Action International Population Connection Population Matters Population Research Institute United Nations Population Fund Voluntary Human Extinction Movement World Population Day World Population Foundation

Related topics	Classic Maya collapse Fertility and intelligence Green Revolution Holocene extinction Migration

Commons Human overpopulation Environmental issues with population Human migration

Lists of countries by population statistics

World population	Current population Current population (United Nations) Current population (graphical)

Continental	Asia Africa Europe North America Oceania South America

Regional	Americas Arab world Caribbean Commonwealth of Nations Eurasia European Union Islands Latin America Middle East

Cities	Population of national capitals Population of cities proper Population of urban areas Population of urban areas Megacity Megalopolis

Past population	Past population (United Nations) Past and future population 1700 1800 1900 1907 2000 2005 2010

Population density	Current density Current real density based on food growing capacity

Growth indicators	Population growth rate Natural increase Birth rate Mortality rate Fertility rate

Other demographics	Age at first marriage Divorce rate Domestic citizens Ethnic and cultural diversity level Foreign-born population Immigrant population Median age Net migration rate Number of households Sex ratio Urban population Urbanization

Health	Antiviral medications for pandemic influenza HIV/AIDS adult prevalence rate Infant mortality rate Life expectancy Percentage suffering from undernourishment Health expenditure covered by government Suicide rate Total health expenditure (PPP) per capita

Education and innovation	25- to 34-year-olds with a tertiary education degree Bloomberg Innovation Index Education Index Graduates in natural sciences and engineering International Innovation Index Innovation Union Scoreboard Literacy rate Programme for the International Assessment of Adult Competencies Progress in International Reading Literacy Study Student skills Trends in International Mathematics and Science Study Women's average years in school World Intellectual Property Indicators

Economic	Development aid given Foreign aid received Employment rate Irrigated land area Human Development Index by country inequality-adjusted Human Poverty Index Imports Income equality Job security Labour force Number of millionaires (US dollars) Number of billionaires (US dollars) Percentage living in poverty Public sector Sen social welfare function Unemployment rate

List of international rankings List of top international rankings by country Lists by country

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Population biology

The Population Extra

See also

External links