week2-people-and-earth.pdf

People and the Earth Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. In sociology and population geography, population refers to a group of humans beings with some predefined criterion in common, such as location, race,...

People and the Earth Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. In sociology and population geography, population refers to a group of humans beings with some predefined criterion in common, such as location, race, ethnicity, nationality, or religion. In ecology, a population is a group of organisms of the same species who inhabit the same particular geographical area and are capable of interbreeding.  Population biology is the study of population characteristics and the factors that affect their size and distribution. Population Characteristics 1. Population Size and Density: Population density is defined as the numbers of individuals per unit area or per unit volume of environment. a. Crude density: It is the density (number or biomass) per unit total space. b. Ecological density or specific or economic density: It is the density (number or biomass) per unit of habitat space i.e., available area or volume that can actually be colonized by the population. 2. Population dispersion or spatial distribution: Dispersion is the spatial pattern of individuals in a population relative to one another (a) Regular dispersion: the individuals are more or less spaced at equal distance from one another (b) Random dispersion: the position of one individual is unrelated to the positions of its neighbors. (c) Clumped dispersion: individuals aggregated into patches interspersed with no or few individuals. 3. Age structure: Age pyramid: Representing geometrically the proportions of different age groups in the population of any organism (a) A pyramids with a broad base (or triangular structure): It indicates a high percentage of young individuals. (b) Bell-Shaped Polygon: It indicates a stationary population having an equal number of young and middle aged individuals. (c) An urn-shaped structure: It indicates a low percentage of young individuals and shows a declining population. 4. Natality (birth rate): a broader term covering the production of new individuals by birth, hatching, by fission, etc. (a) Maximum natality: It is the theoretical maximum production of new individuals under ideal conditions (b) Ecological natality: It is the population increase under an actual, existing specific condition. The rate at which females produce offsprings is determined by the following three population characteristics: (a) Clutch size or the number of young produced on each occasion. (b) The time between one reproductive event and the next and (c) The age of first reproduction. 5. Mortality (death rate): Mortality means the rate of death of individuals in the population. (a) Minimum mortality: It represents the theoretical minimum loss under ideal or non-limiting conditions. (b) Ecological or realized mortality: It is the actual loss of individuals under a given environmental condition. Vital index and survivorship curves: A birth-death ratio (100 x births/deaths) is called vital index. Biotic Potential: The inherent property of an organism to reproduce to survive. Life tables: tabulates the vital statistics of mortality and life expectancy for each group in the population The three main properties of a population Population size - is the number of individuals in a population. Population density - is the average number of individuals in a population per unit of area or volume. Population Distribution Population density just represents the average number of individuals per unit of area or volume. Population growth is the increase in the number of people in a population. The three main causes of population change  Births - usually measured using the birth rate (number of live births per 1,000 of the population per year).  Deaths - usually measured using the death rate (number of deaths per 1,000 of the population per year).  Migration - the movement of people in and out of an area. Carrying capacity The carrying capacity of an environment is the maximum population size of a biological species that can be sustained by that specific environment, given the food, habitat, water, and other resources available. The carrying capacity is defined as the environment's maximal load. Mathematical biologist Joel Cohen classifies current solutions into three paradigms:  those looking for a “bigger pie” (improving technology)  those advocating for “fewer forks” (slowing population growth)  those looking to rationalize and improve decision-making though “better manners” (changing global culture)  Overpopulation is an undesirable condition where the number of the existing human population exceeds the actual carrying capacity of Earth. According to Wikipedia: “Overpopulation occurs when a species’ population exceeds the carrying capacity of its ecological niche. It can result from an increase in births (fertility rate), a decline in the mortality rate, an increase in immigration, or an unsustainable biome and depletion of resources.” Various Causes of Overpopulation 1. The Decline in the Death Rate 2. Agricultural Advancements 3. Better Medical Facilities 4. More Hands to Overcome Poverty 5. Child Labor 6. Technological Advancement in Fertility Treatment 7. Immigration 8. Lack of Family Planning 9. Poor Contraceptives Use  Fatal Effects of Overpopulation 1. Depletion of Natural Resources 7. Malnutrition, Starvation and Famine 2. Degradation of Environment 8. Water Shortage 3. Conflicts and Wars 9. Lower Life Expectancy 4. Rise in Unemployment 10. Extinction 5. High Cost of Living 11. Increased Intensive Farming 6. Pandemics and Epidemics 12. Faster Climate Change Solutions To Overpopulation 1. Better Education 2. Education for Girl Child 3. Making People Aware of Family Planning 4. Tax Benefits or Concessions 5. Knowledge of Sex Education 6. Social Marketing Human impact on ecosystems Human impact on biodiversity Biodiversity is a term used to describe the enormous variety of life on Earth. It can be used more specifically to refer to all of the species in one region or ecosystem. Biodiversity refers to every living thing, including plants, bacteria, animals, and humans. Human-mediated causes of biodiversity loss  Land-use change  Pollution  Introduced species  Resource exploitation  Climate change and biodiversity Fossil fuels are made from decomposing plants and animals. These fuels are found in the Earth's crust and contain carbon and hydrogen, which can be burned for energy. Coal, oil, and natural gas are examples of fossil fuels. Conservation Common mistakes and misconceptions  The extinction rate is currently 1,000-10,000 times higher than the natural extinction rate.  The greenhouse effect is not all negative.  An individual person can have an effect on biodiversity. Term Meaning Biodiversity The variety of organisms in an ecosystem Renewable resources Resources that are replaced as quickly as they are used Resources that are limited in supply because they are used Nonrenewable resources faster than can be replaced The study of the loss of Earth's biodiversity and the ways Conservation this loss can be prevented Process during which all members of a group of organisms Extinction die out Endangered species Species that has been identified as likely to become extinct A biogeographic region that contains high biodiversity and Biodiversity hotspot is also threatened with destruction Climate change Measurable long-term changes in Earth's climate