Question

(a) What is "population" according to you as a biology student? 

(b) “The size of a population for any species is not a static parameter." Justify the statement with specific reference to fluctuations in the population density of a region in a given period of time. 

Answer 1

(a) A population is a group of individuals of the same species living in the same area or interbreeding and sharing genetic information. 

(b) Population density is the number of individuals of a species per unit area/ space at a given time. Various processes affecting population density are:

(i) Natality: It refers to the number of births during a given period in the population that are added to the initial density. 

(ii) Mortality: It is the number of deaths in the population during a given period. 

(iii) Immigration: It is the number of individuals of the same species that have come into the habitat from elsewhere during the time period.

(iv) Emigration: It is the number of individuals of the population who left the habitat and gone elsewhere during the time period.

If N is the population density at time t, then its density at time t + 1 is

N_t+1 = Nt + [(B + I) – (D + E)]

where, B = natality, D = mortality, E = emigration and I = immigration.