This presentation is about population ecology. definition of population ecology, characteristics of population.

1. By
Somya Shukla

2.  Population ecology is a branch of biology that
deals with the study of the individuals of the
same species and their interdependency. It play
vital role in a number of socio-economic
problems both at national as well as
international level.
 A group of organisms of the same species living
in a particular area at a particular time makes a
population.
 Organisms in population undergo the same
lifecycle. They experience similar ecological
process at a particular stage of lifecycle.
 A set of local population connected by dispersing
individuals is called metapopulation.

3.  Population possess several characterstics such as
density, dispersion or distribution, sex ratio, age
distribution, natality, mortality.
 Density: The number of individuals of a species living
in a particular unit space is the density of population.
As we all know density is total mass divided by total
volume in case of liquid so in case of population it is
determined by total number of individual and divided
by number unit space. If total number of individual is
taken as N and the number of space is denoted as S,
then the population density (D) can be calculated as
D=N÷S
 Population density is affected by many factors such
as predators, food security, water, natural resources,
and environmental disasters also affect the density of
population.

4.  Dispersion is arrangement and pattern of the
individual in population within a particular area.
 Population density give us information about how
many individual are present in a particular area while
distribution tell us how they are arranged in that
area.
 Distribution pattern are as following:
 Regular distribution: The organisms that are
dispersed in uniform manner spread at equal distance
from one another.
 Random distribution: Organisms are unevenly
distributed.
 Clumped distribution: The organisms are organized in
cluster form. They are placed at a point within a
area.

5. Emigration: It is movement of out of the
population. This type of dispersal offer the
individual of population to interbred with
individual of other or new population that
leads to genetic heterozygocity.
Immigration: It is a movement of into the
population the population from outside.
 It leads to increase in population density.

6.  The number of individuals in a population are of
different ages. The proportion of individuals in
each age group is called as age structure of that
population.
 Age distribution influences both natality and
mortality. It is an important factor.
 Individual in a population can be divided into
three ecological ages. They are as follows:
 Pre-reproductive (Young age)
 Reproductive (Mature age)
 Post-reproductive (Old age)
 Depending upon the proportion of these age
groups, population are said to be growing,
mature or stable and diminishing.

7.  Age pyramids are hypothetical arrangement of number of
individuals in a various age groups at any given time are
geometrically presented.
(A) (B) (C)
(Expending population) (Stable population) (Decline population)
Post-reproductive
Reproductive
Pre-reproductive

8.  (A) Pyramid with broad base: It shows high
percentage of young individuals and an
exponential growth of population due to high
birth rate.
 (B)Bell-shaped pyramid: It shows a stable
population having equal number of birth and
reproductive rate and death rate is less.
 (C) Urn shaped: In this type of pyramid
reproductive rate is high as compared to birth
and death rate. It shows logistic growth.

9.  Natality is total number of new organisms are
born are natality. The increase in number of
individual in population by hatching, birth,
germination, and vegetative propagation at a
time
 Increase in number of individual is expressed per
unit time, is termed as natality rate.
 Calculation:
 Birth rate or natality rate (N)
 = number of birth per unit time/ average
population
 The maximum number of births produced per
individual under ideal condition of environment
is called potential natality.

10.  The decrease in number of individual in a
population due to death under given
environmental condition is called mortality.
 Mortality rate is number of death per unit
time.
 Moratality rate (M)= D/T
 Whereas, D is number of death per unit time
T.

11. Thank you