New paper studies whale shark genetics from parasites collected from the sharks skin

Whale shark scientists have come up with a novel way of investigating whale shark genetics, using a minimally-invasive technique that focuses not on the shark, but rather on parasites that live on their skin!

The new scientific paper, led by Dr Mark Meekan from Australian Institute of Marine Science (AIMS) Indian Ocean Marine Research Centre, shows that it is possible to collect whale shark invertebrate-derived DNA simply from collecting small parasites, from the sharks' skin. Invertebrate-derived DNA or iDNA involves the extraction of genetic material of animals via invertebrates that parasitise them.

Up until now, most iDNA studies have focused on terrestrial (land) vertebrates and have extracted host DNA from insects, like ticks, or leeches. There has been no comparable studies in marine environments despite this technique offering both a practical and minimally invasive way of studying marine animals. This study is the first to demonstrate the use of iDNA sampling of a marine invertebrate in order to obtain mitochondrial genetic information from an elasmobranch host. Mitochondrial genetic information is genetic material found inside animal cells, which is inherited from the mother; Mitochondrial DNA allows us to study maternal ancestry and in this case population genetics of whale sharks.


 Copepods attached to the pectoral fin of a whale shark.

Copepods attached to the pectoral fin of a whale shark.

With the help of whale shark scientists around the world, including LAMAVE's Dr Alessandro Ponzo (pictured) and one of our close collaborators from Marine Megafauna FoundationDr Simon Pierce, Dr Meeken collected a total of 45 copepods from 31 individual whale sharks. 

Analysis of the iDNA collected indicated the presence of two distinct whale shark populations, one in the Indo-Pacific and the other in the Atlantic Ocean. This is consistent with previous findings.