<unk>  is the branch of<unk>  based solely on visible results of reproductive acts. It is the oldest discipline in the field of<unk> , going back to the experiments on Mendelian inheritance by Gregor Mendel who made it possible to identify the basic mechanisms of heredity. Subsequently, these mechanisms have been studied and explained at the molecular level.<unk>  consists of the techniques and methodologies of<unk>  that were in use before the advent of molecular biology. A key discovery of<unk>  in eukaryotes was<unk> linkage. The observation that some genes do not segregate independently at meiosis broke the laws of Mendelian inheritance, and provided science with a way to map characteristics to a location on the chromosomes. Linkage maps are still used today, especially in breeding for plant improvement. After the discovery of the<unk> code and such tools of cloning as restriction enzymes, the avenues of investigation open to<unk> sts were greatly broadened. Some<unk> ideas have been supplanted with the mechanistic understanding brought by molecular discoveries, but many remain intact and in use.<unk>  is often contrasted with reverse<unk> , and aspects of molecular biology are sometimes referred to as molecular<unk> .
Classical genetics
Behavioural genetics
Germ line theory
Sex linkage
Structural inheritance
Behavioral epigenetics
Epigenetics
Human genetics