DNA barcodes are short sequences of DNA that can be used for identification of a species

• The sequences from which the DNA barcodes are derived are commonly taken from mtDNA in eukaryotes and rRNA in prokaryotes
  

• The barcodes are compiled into online databases that function as a reference library (databases can contain >1 million barcodes)
  

A good DNA barcode will be short in length (~300–600 bp) and consist of two key sections:

• A unique identification sequence (possessing low intraspecific variation but high interspecific variation)
  

• A conserved flanking sequence to allow for the utilisation of universal primers (for wide taxonomic use)
  

Scientists can use DNA barcoding of environmental DNA (eDNA) to monitor the biodiversity of a habitat

• Environmental DNA describes the genetic material released by organisms into their surroundings (soil, water, faeces) 
  

• The eDNA can be used to identify the species present within the environment, without the need for direct observation or invasive tracking methods 
  

DNA Barcodes and eDNA