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Humans experience population growth or decline through , birth rates, immigration, and the development of a country. Factors that go into a population declining or increasing are access to , , and .
enabled the human population to grow because there was an increase in , food and . These basic needs allowed people to live a longer and healthier life.
Human populations continue to change with global trends and patterns, as well as progress. It is important to note that many countries have had improvements with infant mortality rates, as well as general societal improvements, over recent years. Human , though, continue to evolve, and are sometimes predictable.
Rule of 70
A way to predict the doubling time of a population size is by the. This rule states that dividing the number of 70 by the percentage population growth rate approximates the .
Just like there is a for smaller habitats, Earth also has a limit of which can support
Example: A population of birds on a small island has an annual population growth of 2.5%. What is the doubling time for the population ?
Limiting Factors on Population Growth
There are two types of factors that can limit population growth - density independent and density dependent.
Adensity independent factor is a limit on population growth regardless of population density (size). Some examples of are weather, climate, storms, fire, heatwaves, or droughts. For example, a tsunami is not preventable and can not be controlled by competition with resources.
However adensity dependent factor is affected by the size of a population. Some are access to clean water, air, food availability, disease, and territory size.These factors cause damage dependent on how many individuals are affected by them.
Population Formulas
Annual Percent Change - this formula is used to calculate the change in population
Population Growth Rate - this formula calculates the rate at which a population grows.
Population growth rate = (final population size - initial population size) / initial population size
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Key Terms to Review (22)
Annual Percent Change formula: The annual percent change formula is used to calculate the percentage increase or decrease in a value over a period of one year. It compares the difference between the initial and final values to the initial value, and then expresses it as a percentage.
Carrying capacity: Carrying capacity is the maximum number of individuals of a species that an environment can sustainably support without degrading the ecosystem or depleting resources.
Density Dependent Factors: Density dependent factors are environmental factors whose effects on populations depend on their density. These factors include competition for resources, predation, and disease transmission.
Density Independent Factors: Density independent factors are environmental factors that affect populations regardless of their density. These factors include natural disasters, climate change, and pollution.
Disease (in the context of a density dependent factor): A condition caused by pathogens or parasites that can spread more easily when populations are dense. Diseases can have significant impacts on population size and dynamics.
Education: Education refers to the process of acquiring knowledge, skills, values, and attitudes through teaching, training, or research.
Emigration: Emigration refers to the act of individuals or groups leaving their home country to permanently settle in another country. It involves the movement of people across international borders.
Family Planning: Family planning is the practice of controlling the number and spacing of children within a family through contraception methods and reproductive health services. It allows individuals and couples to make informed decisions about when they want to have children and how many they want.
Finite Resources: Finite resources are natural resources that exist in limited quantities and cannot be replenished within a human lifespan. These resources have a finite supply and can eventually be depleted if not managed sustainably.
Food Availability (in the context of a density dependent factor): The amount of food resources present in an ecosystem, which can influence population growth and size. When food availability is limited, it can lead to competition among individuals for resources.
Industrialization: Industrialization refers to the process by which an economy transforms from primarily agricultural-based production to one dominated by manufacturing and industrial activity.
Infant Mortality Rates: Infant mortality rates refer to the number of deaths of infants under one year old per 1,000 live births in a given population. It is an important indicator of the overall health and well-being of a society.
Jobs: Jobs refer to paid positions or occupations in which individuals perform specific tasks or roles to earn a living. They provide individuals with income, opportunities for personal growth, and contribute to the overall functioning of society.
Medicine: Medicine refers to the science and practice of diagnosing, treating, and preventing diseases or injuries in humans.
Nutrition: Nutrition refers to the process by which organisms obtain and utilize food for growth, maintenance, and energy. It involves the intake, digestion, absorption, transport, and utilization of nutrients by living organisms.
Population Doubling Time: Population doubling time refers to the amount of time it takes for a population to double in size. It is calculated by dividing the natural logarithm of 2 by the growth rate.
Population Dynamics: Population dynamics refers to the study of how populations of organisms change in size, density, and structure over time. It involves analyzing factors such as birth rates, death rates, immigration, emigration, and interactions with other species.
Population Growth Rate formula: The population growth rate formula is used to calculate how fast a population is growing or declining over a specific period of time. It takes into account both natural increase (births minus deaths) and net migration (immigration minus emigration).
Rule of 70: The Rule of 70 is a mathematical formula used to estimate the doubling time of a growing quantity based on its annual growth rate. It provides a quick way to determine how long it takes for a population or any other quantity to double in size.
Sanitation: Sanitation refers to the practice of maintaining clean and hygienic conditions in order to prevent the spread of diseases. It involves proper disposal of waste, access to clean water, and personal hygiene practices.
Territory Size (in the context of a density dependent factor): The area occupied by an individual or group that is defended against others. Territory size is influenced by population density and plays a role in resource acquisition and reproductive success.
Weather Events: Weather events are short-term atmospheric conditions, such as storms, heatwaves, or heavy rainfall, that can impact the environment and human populations significantly. These events can lead to various consequences including changes in land use, shifts in agricultural practices, and alterations in human settlement patterns as populations respond to the immediate threats posed by extreme weather. Understanding these events is crucial for analyzing their implications on human population dynamics and planning for future resilience.
