What is the significance of age structure

What are the Different Types of Population Pyramids? By Lauren Boucher | March 10, 2016 A population pyramid, or age structure graph, is a simple graph that conveys the complex social narrative of a population through its shape. Demographers use these simple graphs to evaluate the extent of development for a given population – usually an individual nation – and to make predictions about the types of services that population will need e.g. schools, hospitals, homes, etc. And while every population pyramid is unique, most can be categorized into three prototypical shapes: expansive (young and growing), constrictive (elderly and shrinking), and stationary (little or no population growth). Let’s take a deeper dive into the trends these three shapes reveal about a population and its needs. Not a population pyramid pro? Read our The Three Basic Shapes of Population Pyramids Expansive Expansive population pyramids are used to describe populations that are young and growing. They are often characterized by their typical ‘pyramid’ shape, which has a broad base and narrow top. Expansive population pyramids show a larger percentage of the population in the younger age cohorts, usually with each age cohort smaller in size than the one below it. These types of populations are typically representative of developing nations, whose populations often have high fertility rates and lower than average life expectancies. Constrictive Constrictive population pyramids are used to describe popula...

\( \newcommand\) • • • • • • Population Structure Population growth is the change in the size of the population over time. An important factor in age-sex structure. This is the number of individuals of each sex and age in the population. The age-sex structure influences population growth. This is because younger people are more likely to reproduce, while older people have higher rates of dying. Survivorship Curves Another way to show how deaths affect populations is with survivorship curves. These are graphs that represent the number of individuals still alive at each age. Examples are shown in Figure Survivorship curves reflect death rates at different ages. The three types of curves shown in the figure actually represent different strategies species use to adapt to their environment: • Type I: Parents produce relatively few offspring and provide them with a lot of care. As a result, most of the offspring survive to adulthood so they can reproduce. This pattern is typical of large animals, including humans. • Type II: Parents produce moderate numbers of offspring and provide some parental care. Deaths occur more uniformly throughout life. This pattern occurs in some birds and many asexual species. • Type III: Parents produce many offspring but provide them with little or no care. As a result, relatively few offspring survive to adulthood. This pattern is typical of plants, invertebrates, and many species of fish. The Type I strategy occurs more often in stable environment...

Governments around the world keep records of human birth and death rates—not just for the overall population of a country but also for specific groups within it, broken down by age and sex. Often, this data is arranged in summary tables called life tables. Enterprising insurance companies make good use of these life tables, taking the probability of death at a given age and using it to calculate insurance rates that, statistically, guarantee a tidy profit. Ecologists often collect similar information for the species they study, but they don't do it to maximize profits! They do it to gain knowledge and, often, to help protect species. Take, for example, ecologists concerned about the endangered red panda. They might follow a group of red pandas from birth to death. Each year, they would record how many pandas had survived and how many cubs had been born. From this data, they could better understand the life history, or typical survival and reproduction pattern, of their red panda group. What's the use of a life history? In some cases, ecologists are just plain curious about how organisms live, reproduce, and die. But there is also a practical reason to collect life history data. By combining birth and death rates with a "snapshot" of the current population—how many old and young organisms there are and whether they are male or female—ecologists can predict how a population is likely to grow or shrink in the future. This is particularly important in the case of an endangered...

• • • • Question:What is the significance of the age structure of a population to its current and future growth? A high population of juveniles will lead to high juvenile mortality. It allows you to predict whether the population will grow or decline. It tells you the age of the population. A population that has equal proportions of all age classes is rapidly increasing. What is the significance of the age structure of a population to its current and future growth? A high population of juveniles will lead to high juvenile mortality. It allows you to predict whether the population will grow or decline. It tells you the age of the population. A population that has equal proportions of all age classes is rapidly increasing. Question 2 (1 point) ✓ Saved Which of the following environmental conditions leads to a stable age structure within a population? Fluctuating environmental conditions Population with larger organisms Large number of immature individuals Stable environmental conditions Question 3 (1 point) Table 26.1 Demographic statistics for female pumpkinseed sunfish in Canadian lakes. Means are shown + 1 standard error (SE). GBM, Gonad-tobody mass ratio. Scientists studying sunfish in a series of lakes determined the mean age at maturity, the mean gonadto-body mass ratio (GBM) and the mean length at maturity (Table 26.1). What is the relationship between these three variables? Mean length at maturity is an indicator of the food abundance in the lake, so Beloporine, Blac...

• stable: patterns of birth and death are unchanging over time • stationary: both low birth and death rates (they slope gently inward and have a rounded top) • expansive: slope dramatically inward and upward from the base, indicating that a population has both high birth and death rates • constrictive: signaling low birth and death rates, and expanding outward from the base before sloping inward to achieve a rounded peak at the top The current U.S. age structure and pyramid, shown, is a constrictive model, which is typical of developed countries where family planning practices are common and access to birth control is (ideally) easy, and where advanced medicine and treatments are commonly available through accessible and affordable health care (again, ideally.) That the pyramid moves stably upward through age 59, then only gradually shrinks inward through age 69, and only gets really narrow after age 79 shows us that people are living long lives, which means that the death rate is low. Advances in medicine and elder care over the years have produced this effect in developed countries. Crossman, Ashley. "Age Structure and Age Pyramids." ThoughtCo, Aug. 27, 2020, thoughtco.com/age-structure-definition-3026043. Crossman, Ashley. (2020, August 27). Age Structure and Age Pyramids. Retrieved from https://www.thoughtco.com/age-structure-definition-3026043 Crossman, Ashley. "Age Structure and Age Pyramids." ThoughtCo. https://www.thoughtco.com/age-structure-definition-3026043 (acc...

An age structure diagram, or population pyramid, shows the distribution of age and sex in a population. The y-axis of the diagram shows age groups from birth to old age. The x-axis shows the population percentage. The percentage of males and females in each age group are shown on the left and right sides of the diagram, respectively. • A population experiencing rapid growth has a large proportion of young people and a small proportion of older people. This pattern is seen in populations with high birth and death rates. Rapid growth is common in low- and lower-middle-income countries, where families tend to have more children and individuals have shorter lifespans. An age structure diagram for a rapidly growing population is shaped like a pyramid with sides that curve inward. Other terms for this type of growth include expansive and expanding. • A population experiencing slow growth also has a higher proportion of young people compared to older people, but the difference is not as extreme as in a rapidly growing population. This pattern is seen in populations with a high birth rate and a declining death rate as more people are living into middle or old age. A variety of factors can lead to this age structure, including growth due to immigration or increasing lifespans. An age structure diagram for a slowly growing population is shaped like a pyramid. Like rapid growth, other terms for slow growth include expansive and expanding. • A population that is stable has relatively ...