**13.1 Extraction of DNA from various biological samples**

There is a range of biological samples such as tissue, blood, hair, bone, scat, etc. available to analyze DNA recovered during field surveys. The protocol to apply for DNA extraction varies on the type of sample collected. To extract the DNA from stool, blood, or tissue samples Qiagen fast DNA kit, Germany is widely used and commercially available. Other kits are also available for DNA extraction. Extracted DNA will be useful for studying populations study and wildlife forensics and as well as for genetic studies and the yielded DNA can be checked under 0.8% agarose gel electrophoresis.

## **13.2 Quality assessment of isolated DNA using agarose gel electrophoresis**

Agarose gel electrophoresis is a technique used to resolve DNA fragments on the basis of their molecular weight. Smaller fragments migrate faster than larger ones. The size of fragments can be known by using known size standards DNA ladder, and comparing the distance of unknown fragment. 0.8% agarose is used for the preparation of agarose gel. The contents are boiled in the oven. And 3 μl ethidium bromide (EtBr) is added to the gel. After polymerization, the DNA sample should be loaded and mixed with 5X gel loading dye. Finally, the samples are visualized under the gel documentation system.
