Unit 3 Test

Know what carrying capacity is and how to estimate it from a graph

(K) The maximum population of a given species that a particular habitat can sustain indefinitely without being degraded. The growth rate of a population decreases as its size nears the carrying capacity of its environment because resources such as food, water, and space begin to dwindle. Can be found in a graph by looking for where the population size dwindles up and down. The carrying capacity of an area or volume is not fixed. The carrying capacity of some areas can increase or decrease seasonally and from year to year because of variations in weather and other factors, including an abundance of predators and competitors. For example, a drought can decrease the amount of vegetation growing in an area supporting deer and other herbivores, and this would decrease the normal carrying capacity for those species. Can have negative impacts if exceeded.

Intrinsic rate of increase

(r) The rate at which the population of a species would grow if it had unlimited resources. Individuals in populations with a high intrinsic rate of growth typically reproduce early in life, have short generation times (the time between successive generations), can reproduce many times, and have many offspring each time they reproduce.

Stage 3 name, birth rate trend (stable, increasing or decreasing), death rate trend, and population trend

- Industrial- Birth rates drop (improved food production, health, and education)- Death rates drop (improved food production, health, and education)- Population grows slowly

Know the equations for growth rate (natural/intrinsic rate of increase) and doubling time (see Doubling Time Lab)

- N(t) = N(0)e^rt - r% = CBR-CDR/10 - 70/r% = t

Stage 4 name, birth rate trend (stable, increasing or decreasing), death rate trend, and population trend

- Postindustrial- Birth rates equal and then fall below death rates- Population growth levels off and then declines

Stage 1 name, birth rate trend (stable, increasing or decreasing), death rate trend, and population trend

- Preindustrial- High birth rate (to compensate for high infant mortality)- High death rate- Population grows very slowly/not at all

Stage 2 name, birth rate trend (stable, increasing or decreasing), death rate trend, and population trend

- Transitional- High birth rates- Death rates drop (improved food production and health)- Population grows rapidly

Know some strategies for reducing world poverty

-Focusing on education, hard work, and discipline, all of which attract investment capital. -Make policy changes: emphasize education to develop a trained workforce that can participate in an increasingly global economy. -Analysts have suggested that developed countries and international lending agencies forgive all of this debt for the poorest, most heavily indebted countries, on the condition that the money saved on debt interest be devoted to meeting basic human need. -Governments, businesses, international lending agencies, and wealthy individuals in developed countries could also: Mount a massive global effort to combat malnutrition and the infectious diseases that kill millions of people prematurely/Provide universal primary school education and eradicate illiteracy for nearly 800 million of the world's adults. According to Nobel Prize-winning economist Amartya Sen, "Illiteracy and innumeracy are a greater threat to humanity than terrorism." These problems can foster terrorism and strife within countries by creating large numbers of unemployed individuals who have little hope/Stabilize population growth in developing countries as soon as possible, mostly by investing in family planning, reducing poverty, and elevating the social and economic status of women/Sharply reduce the total and per capita ecological footprints of developed countries and rapidly developing countries such as China and India these growing footprints pose a threat to the world's environmental and economic security/Make large investments in small-scale infrastructure such as solar-cell power facilities in villages and sustainable agriculture projects; such investments could allow developing nations to leapfrog over the conventional development path to more eco-efficient economies/Encourage lending agencies to make small loans to poor people who want to increase their income.

Life expectancy

1 of the 2 useful indicators of the overall health of people in a country or region. The average number of years a newborn infant can expect to live. Between 1955 and 2008, the global life expectancy increased from 48 years to 68 years (77 years in developed countries and 67 years in developing countries) and is projected to reach 74 by 2050. Between 1900 and 2008, life expectancy in the United States increased from 47 to 78 years and, by 2050, is projected to reach 82 years. In the world's poorest countries, however, life expectancy is 49 years or less and may fall further in some countries because of more deaths from AIDS. Even though more is spent on health care per person in the United States than in any other country, people in 41 other countries including Canada, Japan, Singapore, and a number of European countries have longer life expectancies than do Americans. Analysts cite two major reasons for this. First, 45 million Americans lack health care insurance, while Canada and many European countries have universal health care insurance. Second, adults in the United States have one of the world's highest obesity rates.

Infant mortality rate

1 of the 2 useful indicators of the overall health of people in a country or region. The number of babies out of every 1,000 born who die before their first birthday. Infant mortality is viewed as one of the best measures of a society's quality of life because it reflects a country's general level of nutrition and health care. A high infant mortality rate usually indicates insufficient food (undernutrition), poor nutrition (malnutrition), and a high incidence of infectious disease (usually from drinking contaminated water and having weakened disease resistance due to undernutrition and malnutrition). Between 1965 and 2008, the world's infant mortality rate dropped from 20 to 6.3 in developed countries and from 118 to 59 in developing countries. This is good news, but annually, more than 4 million infants (most in developing countries) die of preventable causes during their first year of life—an average of 11,000 mostly unnecessary infant deaths per day. This is equivalent to 55 jet airliners, each loaded with 200 infants younger than age 1, crashing each day with no survivors! The U.S. infant mortality rate declined from 165 in 1900 to 6.6 in 2008. This sharp decline was a major factor in the marked increase in U.S. average life expectancy during this period. Still, some 40 countries, including Taiwan, Cuba, and most of Europe had lower infant mortality rates than the United States had in 2008. Three factors helped keep the U.S. infant mortality rate high: inadequate health care for poor women during pregnancy and for their babies after birth, drug addiction among pregnant women, and a high birth rate among teenagers (although this rate dropped by almost half between 1991 and 2006).

Know the current US & world populations (approximate)

325 million people in the US and 7.5 billion people in the world.

Know the difference between exponential & logistic growth, be able to identify them on a graph, and which most closely models the human population

A population with few, if any, limitations on its resource supplies can grow exponentially at a fixed rate such as 1% or 2% per year. Exponential or geometric growth starts slowly but then accelerates as the population increases, because the base size of the population is increasing. Occurs when resources are not limiting and a population can grow at its intrinsic rate of increase (r) or biotic potential. Plotting the number of individuals against time yields a J-shaped growth curve (left half of curve). Exponential growth is converted to logistic growth. Logistic growth involves rapid exponential population growth followed by a steady decrease in population growth until the population size levels off (right half of curve). This slowdown occurs as the population encounters environmental resistance from declining resources and other environmental factors and approaches the carrying capacity of its environment. After leveling off, a population with this type of growth typically fluctuates slightly above and below the carrying capacity. The size of such a population may also increase or decrease as the carrying capacity changes because of short- or long-term changes in environmental conditions. A plot of the number of individuals against time yields a sigmoid, or S-shaped, logistic growth curve (the whole curve). Humans have exponential growth.

How can availability of birth control affect birth rates and fertility rates?

Also, the availability of reliable birth control methods allows women to control the number and spacing of the children they have.

Know the definitions & characteristics of K-selected species; be able to give some examples

At the other extreme are competitor or K-selected species. They tend to reproduce later in life and have a small number of offspring with fairly long life spans. Typically, for K-selected mammals, the offspring develop inside their mothers (where they are safe), are born fairly large, mature slowly, and are cared for and protected by one or both parents, and in some cases by living in herds or groups, until they reach reproductive age. This reproductive pattern results in a few big and strong individuals that can compete for resources and reproduce a few young to begin the cycle again. Such species are called K-selected species because they tend to do well in competitive conditions when their population size is near the carrying capacity (K ) of their environment. Their populations typically follow a logistic growth curve. Most large mammals (such as elephants, whales, and humans), birds of prey, and large and long-lived plants (such as the saguaro cactus, and most tropical rain forest trees) are K-selected species. Ocean fish such as orange roughy and swordfish, which are now being depleted by overfishing, are also K-selected. Many of these species—especially those with long times between generations and low reproductive rates like elephants, rhinoceroses, and sharks—are prone to extinction.

How can average age of marriage affect birth rates and fertility rates?

Average age at marriage (or, more precisely, the average age at which a woman has her first child) also plays a role. Women normally have fewer children when their average age at marriage is 25 or older.

How can cost of raising and educating children affect birth rates & fertility rates?

Birth and fertility rates tend to be lower in developed countries, where raising children is much more costly because they do not enter the labor force until they are in their late teens or twenties. In the United States, it costs about $290,000 to raise a middle-class child from birth to age 18. By contrast, many children in poor countries have to work to help their families survive.

Know how the following factors can influence genetic diversity: Founder effect

Can occur when a few individuals in a population colonize a new habitat that is geographically isolated from other members of the population. In such cases, limited genetic diversity or variability may threaten the survival of the colonizing population. Website: occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have reduced genetic variation from the original population or a non-random sample of the genes in the original population.

Biotic potential

Capacity for population growth under ideal conditions. Generally, populations of species with large individuals, such as elephants and blue whales, have a low biotic potential while those of small individuals, such as bacteria and insects, have a high biotic potential.

Know the top three most populous countries in the world

China, India, and the United States.

Understand what minimum viable population size is

Conservation biologists use the concepts of founder effects, demographic bottleneck, genetic drift, inbreeding, and island biogeography to estimate it. Of rare and endangered species. The number of individuals such populations need for long-term survival.

Know how the following factors can influence genetic diversity: Bottleneck

Demographic. Occurs when only a few individuals in a population survive a catastrophe such as a fire or hurricane, as if they had passed through the narrow neck of a bottle. Lack of genetic diversity may limit the ability of these individuals to rebuild the population. Even if the population is able to increase in size, its decreased genetic diversity may lead to an increase in the frequency of harmful genetic diseases. Website: occur when a population's size is reduced for at least one generation. Because genetic drift acts more quickly to reduce genetic variation in small populations, undergoing a bottleneck can reduce a population's genetic variation by a lot, even if the bottleneck doesn't last for very many generations. Reduced genetic variation means that the population may not be able to adapt to new selection pressures, such as climatic change or a shift in available resources, because the genetic variation that selection would act on may have already drifted out of the population.

How can availability of legal abortions affect birth rates and fertility rates?

Each year about 190 million women become pregnant. The United Nations and the World Bank estimate that 46 million of these women get abortions—26 million of them legal and 20 million illegal (and often unsafe).

Be familiar with the example of the snowshoe hare & the lynx and some of the controls on these populations

Ecologists distinguish between top-down population regulation, through predation, and bottom-up population regulation, in which the size of predator and prey populations is controlled by the scarcity of one or more resources. In lynx and hare example, top down is predation by lynx and other predators. Bottom up is changes in the availability of food supply for hares helping to determine the hare population size which, in turn, helps determine lynx population size.

Immigration

Entering a population. Population size increases because of birth and this. Part of population change equation. When births plus this exceed deaths plus emigration, population increases; when the reverse is true, population declines.

Density-dependent population control

Examples include predation, parasitism, infectious disease, and competition for resources. Tend to regulate a population at a fairly constant size, often near the carrying capacity of its environment.

Understand what has prevented India from lowering its TFR

For more than 5 decades, India has tried to control its population growth with only modest success. The world's first national family planning program began in India in 1952, when its population was nearly 400 million. By 2008, after 56 years of population control efforts, India had 1.1 billion people. In 1952, India added 5 million people to its population. In 2008, it added 18 million—more than any other country. By 2015, India is projected to be the world's most populous country, with its population projected to reach 1.76 billion by 2050. India faces a number of serious poverty, malnutrition, and environmental problems that could worsen as its population continues to grow rapidly. India has a thriving and rapidly growing middle class of more than 300 million people—roughly equal to the entire U.S. population—many of them highly skilled software developers and entrepreneurs. By global standards, however, one of every four people in India is poor, despite the fact that since 2004 it has had the world's second fastest growing economy, and by 2007, was the world's fourth largest economy. Such prosperity and progress have not touched many of the nearly 650,000 villages where more than twothirds of India's population lives. In 2002, only 18% of its rural population had access to adequate sanitation. In 2006, nearly half of the country's labor force was unemployed or underemployed and 80% of its people were struggling to live on less than $2 (U.S.) day. Although India currently is self-sufficient in food grain production, about 40% of its population and more than half of its children suffer from malnutrition, mostly because of poverty. In 2002, only 5% of the country's land was protected on paper. The Indian government has provided information about the advantages of small families for years and has also made family planning available throughout the country. Even so, Indian women have an average of 2.8 children. Most poor couples still believe they need many children to work and care for them in old age. As in China, the strong cultural preference for male children also means some couples keep having children until they produce one or more boys. The result: even though 90% of Indian couples know of at least one modern birth control method, only 48% actually use one. Like China, India also faces critical resource and environmental problems. With 17% of the world's people, India has just 2.3% of the world's land resources and 2% of the forests. About half the country's cropland is degraded as a result of soil erosion and overgrazing. In addition, more than two-thirds of its water is seriously polluted, sanitation services often are inadequate, and many of its major cities suffer from serious air pollution. India is undergoing rapid economic growth, which is expected to accelerate. As members of its huge and growing middle class increase their resource use per person, India's ecological footprint will expand and increase the pressure on the country's and the earth's natural capital. On the other hand, economic growth may help to slow population growth by accelerating India's demographic transition. By 2050, India—the largest democracy the world has ever seen—could become the world's leading economic power.

Be able to give some examples of countries with declining populations

Germany, Greece, etc.

Know the main factors that have allowed human population increase

Improved food production, health, education, etc.

What are the MDGs?

In 2000, the nations of the world set goals—called Millennium Development Goals—for sharply reducing hunger and poverty, improving health care, achieving universal primary education, empowering women, and moving toward environmental sustainability by 2015. Developed countries agreed to devote 0.7% of their annual national income toward achieving the goals. However, the average amount donated in most years has been 0.25% of national income. The United States—the world's richest country—gives only 0.16% of its national income to help poor countries. Meeting the minimum development goals by increasing aid to 0.7% is an ethical decision that requires developed countries and individuals to reevaluate their priorities (Figure 23-12).

How can infant mortality rate affect birth rates and fertility rates?

In areas with low infant mortality rates, people tend to have fewer children because fewer children die at an early age.

How can religious/cultural beliefs affect birth rates and fertility rates?

In some countries, these factors favor large families and strongly oppose abortion and some forms of birth control.

Understand the basics of China's one-child policy

In the 1960s, Chinese government officials concluded that the only alternative to mass starvation was strict population control. To achieve a sharp drop in fertility, China established the most extensive, intrusive, and strict family planning and population control program in the world. It discourages premarital sex and urges people to delay marriage and limit their families to one child each. Married couples who pledge to have no more than one child receive more food, larger pensions, better housing, free health care, salary bonuses, free school tuition for their child, and preferential employment opportunities for their child. Couples who break their pledge lose such benefits. The government also provides married couples with free sterilization, contraceptives, and abortion. However, reports of forced abortions and other coercive actions have brought condemnation from the United States and other national governments. In China, there is a strong preference for male children, because unlike sons, daughters are likely to marry and leave their parents. A folk saying goes, "Rear a son, and protect yourself in old age." Some pregnant Chinese women use ultrasound to determine the gender of their fetuses, and some get an abortion if it is female. The result: a rapidly growing gender imbalance or "bride shortage" in China's population, with a projected 30-40 million surplus of men expected by 2020. Because of this skewed sex ratio, teen-age girls in some parts of rural China are being kidnapped and sold as brides for single men in other parts of the country. With fewer children, the average age of China's population is increasing rapidly. By 2020, 31% of the Chinese population will be over 60 years old, compared to 8% in 2008. This graying of the Chinese population could lead to a declining work force, higher wages for younger workers, a shortage of funding for continuing economic development, and fewer children and grandchildren to care for the growing number of elderly people. These concerns and other factors may slow economic growth and lead to some relaxation of China's one-child population control policy in the future.

Crude birth rate

Instead of using the total numbers of births and deaths per year, population experts (demographers) use the birth rate, or crude birth rate, or this. The number of live births per 1,000 people in a population in a given year.

Crude death rate

Instead of using the total numbers of births and deaths per year, population experts (demographers) use the the death rate, or this. The number of deaths per 1,000 people in a population in a given year.

Know how the following factors can influence genetic diversity: Genetic drift

It involves random changes in the gene frequencies in a population that can lead to unequal reproductive success. For example, some individuals may breed more than others do and their genes may eventually dominate the gene pool of the population. This change in gene frequency could help or hinder the survival of the population. The founder effect is one cause of genetic drift. Website: Along with natural selection, mutation, and migration — is one of the basic mechanisms of evolution. In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals. The genes of the next generation will be the genes of the "lucky" individuals, not necessarily the healthier or "better" individuals. That, in a nutshell, is genetic drift. It happens to ALL populations — there's no avoiding the vagaries of chance. Genetic drift affects the genetic makeup of the population but, unlike natural selection, through an entirely random process. So although genetic drift is a mechanism of evolution, it doesn't work to produce adaptations. One of the basic mechanisms of evolution — is simply the evolutionary equivalent of a sampling error. Due to many random factors, the genes in one generation do not wind up in identical ratios in the next generation, and this is evolution. It is possible for the frequency of genes for brown coloration to increase in a population of beetles without the help of natural selection. While this is evolution, it is evolution due to chance, not selection. Genetic drift has several important effects on evolution:-Drift reduces genetic variation in populations, potentially reducing a population's ability to evolve in response to new selective pressures.-Genetic drift acts faster and has more drastic results in smaller populations. This effect is particularly important in rare and endangered species.-Genetic drift can contribute to speciation. For example, a small isolated population may diverge from the larger population through genetic drift.

How has population growth influenced our watershed?

It is helpful to think about population growth in terms of watersheds because everything in a watershed will influence the quality of the surface water in that watershed. Monitoring water quality over time is one way to see the effects of a growing population on the local environment. Population has grown in our watershed since the 1850's as it has throughout the Bay Area. The graph to the right shows the trend of population growth in Los Gatos. This trend exhibits logistic growth, showing us that the town appears to be at or near its carrying capacity. The graph below shows the trend of population growth for San Jose, which is still exhibiting exponential growth. In both of these figures, it is clear that the rate of growth was not very high until the 1950's. However, even before that time, it was clear that the Santa Clara Valley would need more water. By 1943 the SC Valley Water District noticed that well water was being depleted quickly, so another source of water was needed. The (Lenihan) Dam was built to form Lexington Reservoir. The reservoir would serve as a water source as well as a way to replenish groundwater. The formation of the reservoir flooded the towns of Alma and Lexington (which had a population of only about 100 people at the time). Currently, drinking water in Los Gatos comes from Lake Ellsman. In addition to an increased need for water, the presence of more people in the Guadelupe Watershed also resulted in an increased need for flood control. The Los Gatos Creek used to have frequent floods. As more and more people moved to this area and the area surrounding the creek was converted from agricultural to residential land, these floods became a bigger issue. To help manage these floods, the river was channelized along much of its length. This gave it higher banks to prevent flooding in town and allows more people to live here. (See photo above showing a view of the channelized portion of the creek just west of Old Town.) Additionally, the building of the Lenihan Dam helped to control the flow of the river to reduce flooding in times of high rainfall. The river was also diverted to make way for Highway 17. (It used to be on the other side of the current Hwy 17). As the Los Gatos Creek has been modified, there have been significant impacts on the natural ecosystem that used to exist in this area. We call the type of ecosystem that existed here a riparian ecosystem. The riparian zone is the community of living things located in and around a river that depend on that river. Riparian zones are transition zones between woodland or grassland and an aquatic environment. They are an example of an ecotone. The channelization and diversion of the river have caused loss of habitat due to removal of vegetation and changes in water quality. Additionally, riparian vegetation holds soil in place and reduces erosion while also providing shade that cools the water. These services are also lost when the vegetation is removed. Riparian communities also serve as transportation corridors for many terrestrial species, so this function has also been lost as portions of the creek have been channelized.

Know how the following factors can influence genetic diversity: Inbreeding

It occurs when individuals in a small population mate with one another. This can occur when a population passes through a demographic bottleneck. This can increase the frequency of defective genes within a population and affect its longterm survival.

Emigration

Leaving a population. Population size decreases because of this and deaths. Part of population change equation. When births plus immigration exceed deaths plus this, population increases; when the reverse is true, population declines.

Know who Thomas Malthus & Paul Ehrlich are and why they are famous

Malthus was one of the first people to apply the concepts of population biology to humans. He was a reverend and a professor in England at the beginning of the industrial revolution (1766-1834). He was one of the first to popularize the idea that the human population had a carrying capacity. In his most famous essay (An Essay on the Principle of Population, 1798), he said that the human population was growing faster than food supplies and would eventually hit a crisis point "Malthusian Catastrophe". However, said that we could avoid this catastrophe because eventually population growth will be stopped by checks such as disease, famine and war. Because of this he was very controversial. He disagreed with contemporaries who were striving for a utopian society/continuous growth, such as Jean-Jacques Rousseau. Malthusian ideas influenced Darwin (& Alfred Russel Wallace) on theory of evolution. There are some things Malthus wasn't aware of when he wrote the essay. For example, often population rises after a war as one side has a plethora of resources that it fought for. Additionally agricultural advances since the time of Malthus have allowed the food supply to grow faster than predicted, preventing widespread famine. Finally, vaccines and medicines developed since the time of Malthus have helped to stop these disease and allowed population to grow in spite of it. However, prosperity has also become a check on pop growth that Malthus did not anticipate; affluent people tend to have fewer children. Paul Ehrlich is another population biologist that has warned of overpopulation. He is the president of the Center of Conservative Biology at Stanford and involved in the Woods Institute for the Environment at Stanford. In 1968 he published The Population Bomb which was similar to Malthus's work. It argued that we must reduce birth rates or we would face the dire consequences of overpopulation, such as running out of food. These did not occur according to Ehrlich's predictions because of agricultural advances (called the Green Revolution) in the 70s. Although Ehrlich was criticized for some predictions not coming true exactly when he said they would, the overall message of the book was accurate.

What is microlending? How does it relate to human population growth?

Most of the world's poor want to earn more, become more self-reliant, and have a better life. But they have no credit record and lack the assets needed for collateral to secure a loan to buy seeds and fertilizer for farming or tools and materials for a small business. For almost 3 decades, an innovation, called microlending or microfinance, has helped large numbers of people to deal with this problem. For example, since economist Muhammad Yunus started it in 1983, the Grameen (Village) Bank in Bangladesh has provided microloans ranging from $50 to $500 to more than 6.6 million Bangladeshi villagers. About 97% of the loans are used by women to plant crops, buy cows, or start their own small businesses as seamstresses, weavers, bookbinders, vendors, and phone service providers. This has empowered women in a male-dominated society and helped to reduce poverty. To stimulate repayment and provide support, the Grameen Bank organizes microborrowers into fivemember "solidarity" groups. If one member of the group misses a weekly payment or defaults on the loan, the other members of the group must make the payments. The Grameen Bank's microlending has been successful and profitable. The repayment rate on these microloans is an astounding 95% compared to 45-50% for loans made by traditional banks in Bangladesh. About half of Grameen's borrowers move above the poverty line within 5 years, and domestic violence, divorce, and birth rates are lower among most borrowers. These microloans have helped more than 5 million borrowers to work their way out of poverty by empowering them and giving them a sense of dignity and hope. Grameen Bank microloans are also being used to develop daycare centers, health care clinics, reforestation projects, drinking water supply projects, literacy programs, group insurance programs, and smallscale solar and wind power systems in rural villages. Grameen's model has inspired the development of microcredit projects that have helped some 50 million people in more than 58 countries, and the numbers are growing rapidly. In 2006, Citibank and TIAA-CREF (a giant academic pension investment fund) each committed $100 million to microloans. In 2006, Muhammad Yunus and his Grameen Bank jointly won the Nobel Peace Prize for their pioneering use of microcredit to assist millions of people in lifting themselves out of poverty.

Know the name of our watershed and what a watershed is

Our watershed is called the Guadelupe Watershed because all the water that falls in it will ultimately end up in the Guadelupe River. Our creek begins at Loma Prieta, behind Mt. Umunhum and flows north into the Guadelupe River and then out to San Francisco Bay. Much of our creek and other creeks in the Guadelupe Watershed have been altered by humans to have engineered channels or to flow in new locations. To understand how population change has influenced our local environment, it is helpful to look at a particular area of land that is influenced by common factors. One way to divide up land is into watersheds. A watershed is a drainage basin. This means that all the land area in that watershed will drain water into the same river/ body of water. Another way of thinking about it is if you imagine a drop of water falling anywhere in the picture to the right, that drop of water will flow downhill into the river pictured. That means that all the land shown in the picture is one watershed.

How can urbanization affect birth rates and fertility rates?

People living in urban areas usually have better access to family planning services and tend to have fewer children than do those living in rural areas (especially in developing countries) where children are often needed to help raise crops and carry daily water and fuelwood supplies.

Know how to interpret population pyramids and be able to predict population & economic change based on them

Pre-reproductive (base) is largest if population is predicted to grow in the future. Post-reproductive (top) is largest if the population is predicted to shrink in the future. Reproductive (middle) is largest if population is predicted to stay stable in the future. This is how you predict population change. Economic change can be predicted by looking at current and future working classes.

Know the 3 age structure categories used in population pyramids. Which one should you look at to predict future population change?

Pre-reproductive, reproductive, and post-reproductive. To predict future population change, should look at size of pre-reproductive category.

How can importance of children in the workforce affect birth rates & fertility rates?

Proportions of children working tend to be higher in developing countries.

Know what family planning is and be able to give some examples

Provides educational and clinical services that help couples choose how many children to have and when to have them. Such programs vary from culture to culture, but most provide information on birth spacing, birth control, and health care for pregnant women and infants. Family planning has been a major factor in reducing the number of births throughout most of the world, mostly because of increased knowledge and availability of contraceptives. According to the U.N. Population Division, 58% of married women ages 15-45 in developed countries and 54% in developing countries used modern contraception in 2008. Family planning has also reduced the number of legal and illegal abortions performed each year and decreased the number of deaths of mothers and fetuses during pregnancy. Studies by the U.N. Population Division and other population agencies indicate that family planning is responsible for at least 55% of the drop in total fertility rates (TFRs) in developing countries, from 6.0 in 1960 to 3.0 in 2008. Between 1971 and 2008, for example, Thailand used family planning to cut its annual population growth rate from 3.2% to 0.5% and its TFR from 6.4 to 1.6 children per family. Another family planning success involves Iran, which between 1989 and 2000, cut its population growth rate from 2.5% to 1.4%. Despite such successes, two problems remain. First, according to the U.N. Population Fund, 42% of all pregnancies in developing countries are unplanned and 26% end with abortion. Second, an estimated 201 million couples in developing countries want to limit the number and determine the spacing of their children, but they lack access to family planning services. According to a recent study by the U.N. Population Fund and the Alan Guttmacher Institute, meeting women's current unmet needs for family planning and contraception could each year prevent 52 million unwanted pregnancies, 22 million induced abortions, 1.4 million infant deaths, and 142,000 pregnancy-related deaths. Some analysts call for expanding family planning programs to include teenagers and sexually active unmarried women, who are excluded from many existing programs. Another suggestion is to develop programs that educate men about the importance of having fewer children and taking more responsibility for raising them. Proponents also call for greatly increased research on developing more effective and more acceptable birth control methods for men. In 1994, the United Nations held its third Conference on Population and Development in Cairo, Egypt. The experiences of countries such as Japan, Thailand, South Korea, Taiwan, Iran, and China show that a country can achieve or come close to replacement level fertility within a decade or two. Such experiences also suggest that the best ways to slow and stabilize population growth are through investing in family planning, reducing poverty, and elevating the social and economic status of women.

Know some of the problems that can result from a rapid decline in population

Reduces the labor force, hampers productivity growth and erodes the domestic market base. Therefore, there is a chance that the macroeconomic growth rate will be in negative territory and as a result per capita growth rate could also be negative.

Total fertility rate

Second type of fertility rate. The average number of children born to women in a population during their reproductive years. This factor plays a key role in determining population size. The average fertility rate has been declining. In 2008, the average global TFR was 2.6 children per woman: 1.6 in developed countries (down from 2.5 in 1950) and 2.8 in developing countries (down from 6.5 in 1950). Although the decline in TFR in developing countries is impressive, the TFR remains far above the replacement level of 2.1, not low enough to stabilize the world's population in the near future.

Density-independent population control

Some factors—mostly abiotic—that can kill members of a population are density independent. In other words, their effect is not dependent on the density of the population. For example, a severe freeze in late spring can kill many individuals in a plant population or a population of monarch butterflies, regardless of their density. Other such factors include floods, hurricanes, fire, pollution, and habitat destruction, such as clearing a forest of its trees or filling in a wetland.

Know the definitions & characteristics of r-selected species; be able to give some examples

Species with a capacity for a high rate of population increase (r ) are called r-selected species. These species have many, usually small, offspring and give them little or no parental care or protection. They overcome typically massive losses of offspring by producing so many offspring that a few will likely survive to reproduce many more offspring to begin this reproductive pattern again. Examples include algae, bacteria, rodents, frogs, turtles, annual plants (such as dandelions), and most insects. Such species tend to be opportunists. They reproduce and disperse rapidly when conditions are favorable or when a disturbance opens up a new habitat or niche for invasion. Environmental changes caused by disturbances, such as fires, clear-cutting, and volcanic eruptions, can allow opportunist species to gain a foothold. However, once established, their populations may crash because of unfavorable changes in environmental conditions or invasion by more competitive species. This helps to explain why most opportunist species go through irregular and unstable boom-and-bust cycles in their population sizes.

Understand how family planning & empowering women to become educated and work outside the home can lower population growth

Studies show that women tend to have fewer children if they are educated, hold a paying job outside the home, and live in societies where their human rights are not suppressed. Although women make up roughly half of the world's population, in most societies they do not have the same rights and educational and economic opportunities as men do. Women do almost all of the world's domestic work and child care for little or no pay and provide more unpaid health care than all of the world's organized health services combined. They also do 60-80% of the work associated with growing food, gathering and hauling wood and animal dung for use as fuel, and hauling water in rural areas of Africa, Latin America, and Asia. As one Brazilian woman put it, "For poor women the only holiday is when you are asleep." Globally, women account for two-thirds of all hours worked but receive only 10% of the world's income, and they own less than 2% of the world's land. Also, about 70% of the world's poor and 64% of all 800 million illiterate adults are women. Because sons are more valued than daughters in many societies, girls are often kept at home to work instead of being sent to school. Globally, some 900 million girls—three times the entire U.S. population—do not attend elementary school. Teaching women to read has a major impact on fertility rates and population growth. Poor women who cannot read often have five to seven children, compared to two or fewer in societies where almost all women can read. According to Thorya Obaid, executive director of the U.N. Population Fund, "Many women in the developing world are trapped in poverty by illiteracy, poor health, and unwanted high fertility. All of these contribute to environmental degradation and tighten the grip of poverty." An increasing number of women in developing countries are taking charge of their lives and reproductive behavior. As it expands, such bottom-up change by individual women will play an important role in stabilizing population and reducing environmental degradation.

How can educational/employment opportunities for women affect birth rates and fertility rates?

TFRs tend to be low when women have access to education and paid employment outside the home. In developing countries, a woman with no education typically has two more children than does a woman with a high school education. In nearly all societies, better-educated women tend to marry later and have fewer children.

How can the availability of pension systems affect birth rates and fertility rates?

The availability of private and public pension systems can influence the decision for some couples on how many children to have, especially the poor in developing countries. Pensions reduce a couple's need to have many children to help support them in old age.

Environmental resistance

The combination of all factors that act to limit the growth of a population. Together, biotic potential and environmental resistance determine the carrying capacity.

Know what replacement-level fertility rate is and why it is higher than 2 children per couple

The first type of 2 fertility rates that affect a country's population size and growth rate. the average number of children that couples in a population must bear to replace themselves. It is slightly higher than two children per couple (2.1 in developed countries and as high as 2.5 in some developing countries), mostly because some children die before reaching their reproductive years. Does reaching replacement-level fertility bring an immediate halt to population growth? No, because so many future parents are alive. If each of today's couples had an average of 2.1 children, they would not be contributing to population growth. But if all of today's girl children also have 2.1 children, the world's population will continue to grow for 50 years or more (assuming death rates do not rise).

Population density

The number of individuals in a population found in a particular area or volume. Some factors that limit population growth have a greater effect as a population's density increases. Examples of such density-dependent population controls include predation, parasitism, infectious disease, and competition for resources. Higher population density may help sexually reproducing individuals find mates, but it can also lead to increased competition for mates, food, living space, water, sunlight, and other resources. High population density can help to shield some members from predators, but it can also make large groups such as schools of fish vulnerable to human harvesting methods. In addition, close contact among individuals in dense populations can increase the transmission of parasites and infectious diseases. When population density decreases, the opposite effects occur. Density-dependent factors tend to regulate a population at a fairly constant size, often near the carrying capacity of its environment. Some factors—mostly abiotic—that can kill members of a population are density independent. In other words, their effect is not dependent on the density of the population. For example, a severe freeze in late spring can kill many individuals in a plant population or a population of monarch butterflies, regardless of their density. Other such factors include floods, hurricanes, fire, pollution, and habitat destruction, such as clearing a forest of its trees or filling in a wetland.

Understand how the US population has changed over time and some of the factors that have influenced it, including migration (p127, 129-130)

The population of the United States grew from 76 million in 1900 to 304 million in 2008, despite oscillations in the country's TFR (Figure 6-4) and birth rates (Figure 6-5). It took the country 139 years to add its first 100 million people, 52 years to add another 100 million by 1967, and only 39 years to add the third 100 million in 2006. The period of high birth rates between 1946 and 1964 is known as the baby boom, when 79 million people were added to the U.S. population. In 1957, the peak of the baby boom, the TFR reached 3.7 children per woman. Since then, it has generally declined, remaining at or below replacement level since 1972. In 2008, the TFR was 2.1 children per woman, compared to 1.6 in China. The drop in the TFR has slowed the rate of population growth in the United States. But the country's population is still growing faster than that of any other developed country, and of China, and is not close to leveling off. About 2.9 million people (one person every 11 seconds) were added to the U.S. population in 2008. About 66% (1.9 million) of this growth occurred because births outnumbered deaths and 34% (1 million) came from legal and illegal immigration (with someone migrating to the U.S. every 32 seconds). In addition to the almost fourfold increase in population growth since 1900, some amazing changes in lifestyles took place in the United States during the 20th century (Figure 6-6, p. 128), which led to dramatic increases in per capita resource use and a much larger U.S. ecological footprint. Here are a few more changes that occurred during the last century. In 1907, the three leading causes of death in the United States were pneumonia, tuberculosis, and diarrhea; 90% of U.S. doctors had no college education; one out of five adults could not read or write; only 6% of Americans graduated from high school; the average U.S. worker earned $200-400 per year and the average daily wage was 22 cents per hour; there were only 9,000 cars in the U.S., and only 232 kilometers (144 miles) of paved roads; a 3-minute phone call from Denver, Colorado, to New York city cost $11; only 30 people lived in Las Vegas, Nevada; most women washed their hair only once a month; marijuana, heroin, and morphine were available over the counter at local drugstores; and there were only 230 reported murders in the entire country. According to U.S. Census Bureau, the U.S. population is likely to increase from 304 million in 2008 to 438 million by 2050 and then to 571 million by 2100. In contrast, population growth has slowed in other major developed countries since 1950, most of which are expected to have declining populations after 2010. Because of a high per capita rate of resource use and the resulting waste and pollution, each addition to the U.S. population has an enormous environmental impact. Since 1820, the United States has admitted almost twice as many immigrants and refugees as all other countries combined. The number of legal immigrants (including refugees) has varied during different periods because of changes in immigration laws and rates of economic growth (Figure 6-7). Currently, legal and illegal immigration account for about 40% of the country's annual population growth. Between 1820 and 1960, most legal immigrants to the United States came from Europe. Since 1960, most have come from Latin America (53%) and Asia (25%), followed by Europe (14%). In 2007, Latinos (67% of them from Mexico) made up 15% of the U.S. population, and by 2050, are projected to make up 25% of the population. According to the Pew Hispanic Center, 53% of the 100 million Americans that were added to the population between 1967 and 2007 were either immigrants or their children. There is controversy over whether to reduce legal immigration to the United States. Some analysts would accept new entrants only if they can support themselves, arguing that providing legal immigrants with public services makes the United States a magnet for the world's poor. Proponents of reducing legal immigration argue that it would allow the United States to stabilize its population sooner and help reduce the country's enormous environmental impact from its huge ecological footprint. Polls show that almost 60% of the U.S. public strongly supports reducing legal immigration. There is also intense political controversy over what to do about illegal immigration. In 2007, there were an estimated 11.3 million illegal immigrants in the United States, with about 58% of them from Mexico and 22% from other Latin American countries. Those opposed to reducing current levels of legal immigration argue that it would diminish the historical role of the United States as a place of opportunity for the world's poor and oppressed and as a source of cultural diversity that has been a hallmark of American culture since its beginnings. In addition, according to several studies, including a 2006 study by the Pew Hispanic Center, immigrants and their descendants pay taxes, take many menial and low-paying jobs that most other Americans shun, start new businesses, create jobs, add cultural vitality, and help the United States succeed in the global economy. Also, according to the U.S. Census Bureau, after 2020, higher immigration levels will be needed to supply enough workers as baby boomers retire. According to a recent study by the U.N. Population Division, if the United States wants to maintain its current ratio of workers to retirees, it will need to absorb an average of 10.8 million immigrants each year—more than 13 times the current immigration level—through 2050. At that point, the U.S. population would total 1.1 billion people, 73% of them fairly recent immigrants or their descendants. Housing this influx of almost 11 million immigrants per year would require the equivalent of building another New York City every 10 months.

Know what factors can affect death rates

The rapid growth of the world's population over the past 100 years is not primarily the result of a rise in the crude birth rate. Instead, it has been caused largely by a decline in crude death rates, especially in developing countries. More people started living longer and fewer infants died because of increased food supplies and distribution, better nutrition, medical advances such as immunizations and antibiotics, improved sanitation, and safer water supplies (which curtailed the spread of many infectious diseases).

Know the 3 types of population distribution, why they might occur and be able to give examples of each

Three general patterns of population distribution or dispersion in a habitat are clumping, uniform dispersion, and random dispersion. In most populations, individuals of a species live together in clumps or patches. Examples are patches of desert vegetation around springs, cottonwood trees clustered along streams, wolf packs, flocks of birds, and schools of fish. The locations and sizes of these clumps and patches vary with the availability of resources. Southern sea otters, for example, are usually found in groups known as rafts or pods ranging in size from a few to several hundred animals. Why clumping? Several reasons: First, the resources a species needs vary greatly in availability from place to place, so the species tends to cluster where the resources are available. Second, individuals moving in groups have a better chance of encountering patches or clumps of resources, such as water and vegetation, than they would searching for the resources on their own. Third, living in groups protects some animals from predators. Fourth, hunting in packs gives some predators a better chance of finding and catching prey. Fifth, some species form temporary groups for mating and caring for young. Some species maintain a fairly constant distance between individuals. Because of its sparse distribution pattern, creosote bushes in a desert have better access to scarce water resources. Organisms with a random distribution are fairly rare. The living world is mostly clumpy and patchy.

Know how poverty contributes to human population growth

When in poverty, typically need more children in the workforce, lower cost of raising and educating children, less urbanization, less education/employment opportunities for women, higher infant mortality rate, lower average age at marriage, less availability of legal abortions and birth control, and more religious/cultural beliefs: all accounting for higher birth rates and fertility rates.

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