Question

Short / Long answer type questions
Why is genetic variability essential for a species to survive? Name the main sources of genetic variation. How do these sources work?

Answer 1

Variations result in an increase in genetic diversity. This is important due to the following reasons:

• When a population of an organism contains a large gene pool the group has a greater chance of surviving and flourishing than a population with limited genetic variability. Because of inherited traits making them particularly resistant to disease or tolerant of cold.
  
• Higher genetic variability leads to more likelihood that at least some of the individuals will be resistant, and will survive.
  
• It reduces the incidence of unfavorable inherited traits.

The main sources of genetic variability are:

• In sexually reproducing organisms, during prophase-I of meiosis the homologous pairs of chromosomes come together (synapsis) and exchange of segments of chromosomal segments occur between the two homologous chromosomes. The crossing over and exchange of the chromosomal segments occurs between non-sister chromatids. This, therefore, helps in the exchange of genetic materials from the two parents and introduce a new chromosome complement leading to new traits in the offspring. So, crossing over results in variations in sexually reproducing organisms.
  
• The separation of sister chromatids and their random distribution to daughter cells or gametes is one another reason for the generation of variations in sexually reproducing organisms.