Question

Describe the equation

$N_{t+1}$ =$N_t$ + $\left[\right(B+I)–(D+E\left)\right]$

Mention the different ways by which the population density of different species can be measured.

Answer 1

a) This equation Nt+1 =Nt + [(B + I) – (D + E)] shows the population density at time = t+ 1.

• where, N = Population density, t = Time, B = Birth rate, I = Immigration, D = Death rate, E = Emigration and Nt = Population in beginning.
• The equation demonstrates that the population density will increase if the number of births plus the number of immigrants (B + I) is more than the number of deaths plus the number of emigrants (D + E), otherwise, it will decrease.
  

b) Population density is the number of individuals of a species per unit area or volume.

• The different ways by which the population density of different species can be measured are:-
• 1) Natality- is the number of births during a given period in the population.

2) Mortality- is the number of deaths in the population during a given period.

3) Immigration- is the number of individuals that have come into the habitat from elsewhere during the time period.
4) Emigration- is the number of individuals of the population who left the habitat and moved elsewhere during a given time period.