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population
1.
2. Name – Gurjit Kaur
Class – 9th E₂
Roll No. – 5
House no. – T-841
3. INTRODUCTION
A population is a summation of all the organisms of
the same group or species, who live in the
same geographical area, and have the capability of
interbreeding.In ecology the population of a certain
species in a certain area is estimated using the Lincoln
Index. The area that is used to define
a sexual population is defined as the area where inter-
breeding is potentially possible between any pair within
the area. The probability of interbreeding is greater than
the probability of cross-breeding with individuals from
other areas. Under normal conditions, breeding is
substantially more common within the area than across
the border.
In sociology, population refers to a collection
of human beings. Demography is a social
science which entails the statistical study of human
4. Population genetics
In population genetics a sexual population is a set of organisms in which any
pair of members can breed together. This means that they can regularly
exchange gametes to produce normally-fertile offspring, and such a breeding
group is also known therefore as a gamodeme. This also implies that all members
belong to the same of species, such as humans. If the gamodeme is very large
(theoretically, approaching infinity), and all gene alleles are uniformly
distributed by the gametes within it, the gamodeme is said to be panmictic.
Under this state, allele (gamete) frequencies can be converted to genotype
(zygote) frequencies by expanding an appropriate quadratic equation, as shown
by Sir Ronald Fisher in his establishment of quantitative genetics.
Unfortunately, this seldom occurs in nature : localisation of gamete exchange –
through dispersal limitations, or preferential mating, or cataclysm, or other
cause – may lead to small actual gamodemes which exchange gametes
reasonably uniformly within themselves, but are virtually separated from their
neighbouring gamodemes. However, there may be low frequencies of exchange
with these neighbours. This may be viewed as the breaking up of a large sexual
population(panmictic)into smaller overlapping sexual populations. This failure
of panmixia leads to two important changes in overall population structure: .the
component gamodemes vary (through gamete sampling) in their allele
frequencies when compared with each other and with the theoretical panmictic
original nd the level of homozygosity rises in the entire collection of
gamodemes.
5. As of today's date, the world population is estimated by the United States
Census Bureau to be Expression error: Unrecognized punctuation
character . billion.The US Census Bureau estimates the 7 billion number
was surpassed on 12 March 2012. According to a separate estimate by the
United Nations, Earth’s population exceeded seven billion in October 2011, a
milestone that offers unprecedented challenges and opportunities to all of
humanity, according to UNFPA, the United Nations Population Fund.
According to papers published by the United States Census Bureau, the
world population hit 6.5 billion on 24 February 2006. The United Nations
Population Fund designated 12 October 1999 as the approximate day on
which world population reached 6 billion. This was about 12 years after
world population reached 5 billion in 1987, and 6 years after world
population reached 5.5 billion in 1993. The population of some countries,
such as Nigeria, is not even known to the nearest million, so there is a
considerable margin of error in such estimates.
Researcher Carl Haub calculated that a total of over 100 billion people have
probably been born in the last 2000 years.
6. In the year 2005, the world population isestimated to have reached
6.5 billion, more than two and a half times the level in 1950;
according to the medium-variant projection of the 2004 Revision, it is
expected to reach 9.1 billion in 2050 The less developed regions, with
5.3 billion people in 2005, account for the vast majority of the world
population (81.3 per cent). The more developed regions have an
estimated population of 1.2 billion, or 18.7 per cent of the world
population. More and more of the world’s inhabitants are coming to
reside in the less developed regions, increasing from 67.7 per centin
1950 to a projected 86.4 per cent in 2050.Within the less developed
regions in 2005, the least developed countries account for about 0.8
billion and otherless developed countries for 4.5 billion. The share of
the least developed countries is projected to grow from 8.0 per cent
in 1950 to 19.1 per cent in 2050.
7.
8. Population growth is the change in a population over time, and can
be quantified as the change in the number of individuals of
any species in a population using "per unit time" for measurement.
In biology, the term population growth is likely to refer to any
known organism, but this article deals mostly with the application of
the term to human populations indemography.
Population growth rates might have declined, but in 2013 every 60
minutes there are another 8,000 people in the world: about 75
million every year.
In demography, population growth is used informally for the more
specific term population growth rate (see below), and is often used
to refer specifically to the growth of the humanpopulation of the
world.
Simple models of population growth include the Malthusian Growth
Model and the logistic model.
The world population grew from 1 billion to 7 billion from 1800 to
2011. During the year 2011, according to estimates, 135 million
people were born and 57 million died, for an increase in population
of 78 million.
10. Three Processes of Population
Change
Natural increase of population is the difference between birth rates and death
rates.
Birth rate is the number of live births per thousand persons in ayear.It is a
major component of growth in India because birth rates have always been
higher than death rates here.
Death rate is the number of deaths per thousand persons in a year.Main cause
of rapid rate of growth of the Indian population is the fast decline in the death
rates
Migration is the third component of population growth:
It is the movement of people across regions and territories.
ii. It is both internal and international.
Internal migration is the movement of people from one region to another
within the country.
International migration is the movement of people from one to another
country.
11. A further demographic feature that has implications for current
economic status and future economic need is the contrast
between the age distribution of the Indigenous and non-
Indigenous populations (as shown in for the East Kimberley
region as a whole. For the Indigenous population, several
features are noteworthy. First, the broad base of the age
pyramid describes a population with continued high fertility (a
Total Fertility Rate (Second, the rapid taper with advancing age
highlights continued high adult mortality. Using the ABS
experimental Indigenous life table for the Northern Territory
(which arguably reflects age-specific mortality rates closest to
those of the East Kimberley population), life expectancies for
males and females are seemingly stuck at around 56 and 63
years respectively, with much of the excess mortality occurring in
adult Third, uniformity in the decline of population with age
suggests net inter-regional migration balance. Finally, the
relatively large numbers of women in the childbearing ages, and
the even larger cohorts beneath them, indicate substantial
population momentum with associated high potential for future
growth in numbers. Actual numbers in each age group are
shown for Indigenous males and females in
