Population Ecology

Population Ecology

The word population is derived from latin word 'populus' which means people. Organism in nature rarely grow as separate from each other. Each species in an ecosystem exist as a population.

Population:   Population is the group of organisms of the same species that live in a particular geographic region at the same time with capability of interbreeding. 

Population ecology defined how these population interact with the environment. It deal with the pattern in the abundance and distribution of organisms that produce this.

There are two types of population.

A. Unitary population

B. Modular population.

A. Unitary population: 

 In unitary population each individuals is originated from zygote ( The product of fertilization of male and female gamete ) 

 and growth of such individuals is determinant and predictable.

Example: Mammals, Birds, Amphibian, Insects.

B. Modular population: 

In case of modular population, zygote develops into unit, or module, which produces more modules thus producing an organism with a variable number of modules, whose development is unpredictable and strongly e influenced by environmental.

Example: Plants, Sponges, Fungi, Bacteria, and Corals.

Monospecific population: 

Monospecific population means the population of only one species living at same area is called Monospecific population.

Polyspecific or mixed population:

 It is the population of different species (more than one species) living in the same area are called polyspecific or mixed population.

Different attributes of a population:

1. Birth rate ( natality) and  Death rate mortality.

2. Sex ratio.

3. Age distribution.

4. Population Density.

Birth rate ( Natality) : Natality is the number of children getting by birth per unit time of a population.

N = nD           N = Natality, 

         t            nd= No of new individuals

                        t= time 

Death Rate of Mortality: 

Death rate ormortality means the number of death individuals per unit time of a population.

         

M = md       M = Mortality

          t         md = Number of death individual

                     t= time.

Sex ratio: 

it is the ratio between males and females of a specific population in an area.

Age distribution: 

population countries different age groups such as reproductive reproductive and post reproductive age groups. This age distribution is graphically represented by an age pyramid. the age pyramid indicates whether a population is growing, stable or declining.

Population density:

Number of individuals of the population per unit area or unit volume.

Population density  =  number of individuals

                                                      Area.

Population density is divided into two major categories such as

A. Crude density

B. Specific or ecological density.

A. Crude density: 

number of individuals of the same species part total unit area or volume is called current density.

Example: the number of deers living in the Surulia mini jungle (Purulia.)

Specific or ecological density: 

Number of individuals of the same species per unit area that is used by the species.

Example: Say for example deers do not occupy all area of Surulia mini  Jungle but it may avoid some of the area due to lack of food, Shelters and human habitation. Therefore the area in habitat by the deer actually will be ecological density.

Age structure: 

In the most type of populations individuals are of different age. The proportion of individuals in each group is called a structure of that population. The ratio of the various age groups in a population determines the current reproductive status of the population.

Chohort: 'Chohort' reffers to a group of people having same age and characteristic features in a population.

Age pyramid: Pyramid is a graphical illustration that shows the distribution of various age groups in a population which forms the shape of a pyramid when a population growing.

Age pyramids are divided into three major groups such as

1. Expanding population

2. Stable population

3. Diminishing population