New DNA extraction method broadens mollusc studies

FOR centuries, scientists have been saying ‘‘What the shell’’ when studying molluscs.

Now, a new DNA extraction technique being used at the University of Otago aims to improve conservation approaches for endangered and neverbeforeseenalive molluscs.

Research author and zoology PhD candidate Kerry Walton said there were about 200,000 different species of mollusc, making them the secondmost diverse animal group after arthropods.

The shells of clams, oysters, mussels, and snails were robust and could last in some environments for hundreds or even thousands of years.

‘‘About half of living mollusc species have never been seen or collected alive, and are only known from their shells.

‘‘While there are hundreds of thousands of mollusc specimens in museum collections in New Zealand, only a few thousand — a tiny fraction — are suitable for conventional genetic research approaches.

‘‘We managed to develop a combination of methods that improved the retrieval of DNA and sequencing of genomes from mollusc shell by up to 350fold [compared with] previous methods, and we did so in a way that proved reliable and relatively affordable, without destroying the specimens.’’

He said the results provided better understanding around how different regional species related to one another, and allowed novel questions to be answered.

‘‘Enabling researchers to use historically collected shells rather than relying on freshly collected specimens, would significantly increase the number of specimens and species available for genetic research.

‘‘This would enable, for example, conservation genetic approaches to be applied to endangered or neverbeforeseenalive molluscs.

‘‘A better understanding of invertebrates is critical to understanding soil or water health, and ecosystems as a whole.’’

Mr Walton believed natural history collections, often housed in museums, were extremely important but often understated.

‘‘We can now look at how genetic diversity in molluscs have changed through time, from before human arrival in Aotearoa to the present day, and use that information to better understand evolutionary processes and provide evidencebased conservation management guidelines for our taonga species.’’

PHOTO: PETER MCINTOSH Treasure trove of information . . . University of Otago zoology PhD candidate Kerry Walton (and inset) with a Haliotis Australis shell, one of many he will be extracting DNA from as part of his research.