mortality rate

(noun)

the number of deaths per given unit of population over a given period of time

Related Terms

Examples of mortality rate in the following topics:

  • The Study of Population Dynamics

    • the probability of individuals dying before their next birthday (i.e., mortality rate)
    • The mortality rate per 1,000 individuals is calculated by dividing the number of individuals dying during an age interval by the number of individuals surviving at the beginning of the interval, multiplied by 1,000.
    • This number is then multiplied by 1,000 to get the mortality rate per thousand.
    • As can be seen from the mortality rate data (column D), a high death rate occurred when the sheep were between 6 and 12 months old, which then increased even more from 8 to 12 years old, after which there were few survivors.
    • This life table of Ovis dalli shows the number of deaths, number of survivors, mortality rate, and life expectancy at each age interval for the Dall mountain sheep.

  • Density-Dependent and Density-Independent Population Regulation

    • Population regulation is a density-dependent process, meaning that population growth rates are regulated by the density of a population.
    • Usually, the denser a population is, the greater its mortality rate.
    • For example, during intra- and interspecific competition, the reproductive rates of the individuals will usually be lower, reducing their population's rate of growth.
    • In addition, low prey density increases the mortality of its predator because it has more difficulty locating its food source.
    • Many factors, typically physical or chemical in nature (abiotic), influence the mortality of a population regardless of its density.

  • Human Population Growth

    • The "population growth rate" is the rate at which the number of individuals in a population increases in a given time period as a fraction of the initial population.
    • In 2009, the estimated annual growth rate was 1.1%.
    • The CIA World Factbook gives the world annual birthrate, mortality rate, and growth rate as 1.89%, 0.79%, and 1.096% respectively.
    • Each region of the globe has seen reductions in growth rate in recent decades, though growth rates remain above 2% in some countries of the Middle East and Sub-Saharan Africa, and also in South Asia, Southeast Asia, and Latin America.
    • However, some countries do experience negative population growth, mainly due to low fertility rates, high death rates and emigration.

  • Overcoming Density-Dependent Regulation

    • Developing countries have also made advances in curbing mortality from infectious disease.
    • The advent of modern medicine is very closely tied to childhood mortality, as well as the number of children per mother (Fertility Rate).
    • As modern medicine decrease child mortality, the birth rate decreases.

  • History of Bacterial Diseases

    • Although contracting bubonic plague before antibiotics meant almost certain death, the bacterium responds to several types of modern antibiotics; mortality rates from plague are now very low.

  • Overharvesting

    • Ecologists use the term to describe populations that are harvested at a rate that is unsustainable, given their natural rates of mortality and capacities for reproduction.

  • Age Structure, Population Growth, and Economic Development

    • A population's growth rate is strongly influenced by the proportions of individuals of particular ages.
    • Age structure data allow the rate of growth (or decline) to be associated with a population's level of economic development.
    • Improved health care, beginning in the 1960s, is one of the leading causes of the increased growth rates that created the population explosion.
    • The percent growth rate of population in different countries shows that the highest growth rates are in underdeveloped regions of Africa and Asia.
    • The relatively few young people may not be making up for the mortality among the older age groups.

  • Theories of Life History

    • The first variable is K (the carrying capacity of a population; density dependent), and the second variable is r (the intrinsic rate of natural increase in population size, density independent).
    • As many as 50,000 acorns can be produced by an individual tree, but the germination rate is low as many of these rot or are eaten by animals such as squirrels.
    • Furthermore, the theory ignored the age-specific mortality of the populations which scientists now know is very important.
    • New demographic-based models of life history evolution have been developed which incorporate many ecological concepts included in r- and K-selection theory, as well as population age structure and mortality factors.

  • Protists as Human Pathogens

    • During epidemic periods, mortality from the disease can be high.

  • Exponential Population Growth

    • Therefore, when calculating the growth rate of a population, the death rate (D; the number organisms that die during a particular time interval) is subtracted from the birth rate (B; the number organisms that are born during that interval).
    • where $\Delta N$ = change in number, $\Delta T$ = change in time, $B$ = birth rate, and $D$ = death rate.
    • The birth rate is usually expressed on a per capita (for each individual) basis.
    • Thus, B (birth rate) = bN (the per capita birth rate "b" multiplied by the number of individuals "N") and D (death rate) = dN (the per capita death rate "d" multiplied by the number of individuals "N").
    • The difference between birth and death rates is further simplified by substituting the term "r" (intrinsic rate of increase) for the relationship between birth and death rates: