Figure 1.

A wide variety of interactions occur in nature and all cases leave behind traces of environmental DNA. Clockwise starting at top left, DNA from crushed insects (B, C, D) in faeces can identify the insect prey and the predators DNA is present in traces, bees carry pollen, which provides plant DNA, parasites blood meals are a source of DNA from visited animals, chewed seeds have saliva and deposited seeds epithelial cells, which can be used to identify the dispersing animal (Photographs used with permission: mosquito – M. Brock Fenton, bee – L. Packer and Bee Tribes of the World, all others E.L. Clare).