A likely extinct species of land snail, native to the Galapagos, could be studied using a method of DNA extraction tested by researchers at the University of Idaho.
DNA can be difficult to extract from snail shells, according to UI and Washington State University researchers, who published their article in the Malacological Society of London Journal of Molluscan Studies in 2016.
UI Professor Christine Parent, who studies rare and extinct snails in the Galapagos, said shells can provide valuable information.
“When organisms die, typically their body decomposes and disappears very quickly in the environment. However, with snails, although the animal disappears quickly, the shell is left behind and we can extract a lot of information from the shell. You can infer what habitat that species liked, but that’s about it,” Parent said. “One bit of information we were not able to understand is how they’re related.”
To understand the family tree of a particular snail species, Parent said she needs their DNA.
She said snail shells are a secretion made primarily of minerals — not cells — making it hard to find any living tissue to extract DNA from. Though the shells are not composed of living tissue, she said a few cells can be trapped as the shells form.
“Usually, tissue must be well preserved after collection or DNA will degrade quickly,” Parent said. “The shell creates a perfect preservation of the tissue.”
Researchers used shells Parent received from a colleague who collected them from 1965 to 1966 and shells Parent collected in her own research from 2000 to 2014. Both samples originated from the Galapagos, a region experiencing a significant decline in snail populations, Parent said.
The shells were taken to WSU for testing by researchers Brian Kemp and then-graduate student Fernando Villanea. There, the team used ancient DNA extraction, a method typically used on old bones or animal or plant remains in anthropological studies, on the empty snail shells and found it to be more successful than previous methods of extraction.
“The combination of using the technique of ancient DNA — merging of this anthropological approach to a biological question — opens up possibilities people just didn’t think of,” Parent said. “It’s sort of cliche, but it’s like opening up our horizons to see what our neighbors are doing and finding how something can be applicable in an interdisciplinary way.”
The ancient DNA method proved to significantly reduce the number of inhibited samples — down to 29 percent versus 86 percent in the traditional method.
Parent said the results could help scientists understand how snails and other mollusks have evolved over time and allow greater understanding of extinct species.
“For people who work on species that are rare, we can extract data without killing specimens,” Parent said. “Especially in ecosystems like the Galapagos, it can be difficult to get permits to collect specimens. But more importantly, we don’t want to kill organisms if we have a way to collect information about them without having to sacrifice individuals.”
Nishant Mohan can be reached at [email protected]