The science of Genetics deals with the principles that explain the similarities between parents and their progeny. All living organisms fundamentally have the capacity of reproduction.The reproduction is the production of a new generation of offsprings that resembles the parental generations.It involves the transfer of biological information of parental generation to the new organism via the egg a
nd sperm. The offspring of dogs always resemble with their parents and never with cats or elephants.This tendency of individuals to resemble their progenitors is called Heredity. Though the offspring of a species may resemble very closely to their parents but they never resemble exactly with them.The offsprings of a particular set of parents differ from each other and from their parents in many respects and to different degrees. In other words we can say that each species has individuality i.e., each species is recognisable by its certain specific morphologyical,physiological and behavioural characteristics by whic he is easily recognised by other persons.The characters which provide individuality to a species are said to cause VARIATION among the species. THE VARIATIONS MAY BE OF FOLLOWING TWO KINDS:
1-HEREDITY VARIATION[inheritance variation]
2-ENVIRONMENTAL VARIATION. HEREDITY VARIATION:It refers to differences in inherited characteristics.Traits which are present in parents can ressort and give rise to different combinations,which are responsible for heredity variations within the same progeny.Heridity variations are caused by genes are called genotypic variation. 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 organism are called environmental variation.
