Principles of Genetics and Breeding

1.1.1 Introduction

Genetics is a science that deals with study of heredity and variation in living organisms.

Heredity deals with the transmission of "genes" and hence characters, from parents to offsprings.

The variations may be of following two kinds:

1. Hereditary variations

• Among the sexually reproducing organisms no two individuals have the same heredity.
• The differences in hereditary constitutions (genotype) of the individuals of a species are known as hereditary or genetic variations.
• Variations can also be caused due to mutation that are hereditary.

2. Environmental variations

• The variations which are not inherited but are due to the effects of temperature, moisture, food, light or other environmental factors on the development of the organisms are called environmental variations.
• For example, the differences between a well-nourished and malnourished person.
• The heredity and variations have a significant role in the formation of new species (i.e., speciation).