Approximately 40,000 frozen tissue samples
Genetic analysis today is not what it used to be—and techniques continue to evolve.
“We’re in the age of genomics, and pretty soon it’ll be so cheap to sequence that we’ll just take a sample, throw it in the sequencer and do the whole genome,” says Keith Barker, curator of the Bell’s genetic resources collection.
Of course, prices have to come down first, but they are moving in the right direction. Not only is it becoming more affordable to sequence DNA, it’s getting easier. Modern methods can use samples not just from tissues but also from dried museum skins, which means even old specimens can still provide the material necessary for sophisticated genetic analysis.
Until recently, so-called Sanger sequencing used to be the state of the art, and this technique required relatively high quality DNA. For many purposes, the newer methods can use tiny pieces of DNA, Barker says, although high quality “reference” genomes still require material quickly frozen in the field and carefully stored in archival conditions. New techniques are also faster—rather than processing 96 samples one gene at a time, they can sequence thousands of genes at once.
Genetic resources are a key component of most of our museum collections. The genetic resources collection includes samples from plants of Papua New Guinea (gathered by George Weiblen, Bell science director and curator of plants), Ozarks fishes (collected by Andrew Simons, curator of the Bell’s fishes collection), Appalachian salamanders (from Ken Kozak, curator of the Bell’s amphibian and reptile collection), birds (especially from Minnesota, the Caucasus mountains, and western North America) collected by Bob Zink and his former graduate students, as well as Barker himself.
Barker is constantly adding to the collection, which is kept in freezers that are carefully monitored by University facilities staff, and served by backup generators. Sources for new samples include carcasses from The Raptor Center, the Audubon Lights Out program, wildlife rehabilitation centers, and ongoing projects in the labs of Barker and curator of birds Sushma Reddy.
How are these genetic resources used within the university? One study that Barker is working on is species limits in the marsh wren complex. Currently only one species is recognized, but there are definitely two (as different genetically as humans and chimpanzees) and possibly as many as four good species in this group. The Bell’s collection has a large number of Mexican marsh wrens, and when split the Bell will have the largest collection in the world of the endemic Mexican species.
Barker explains that the Mexican form is the most distinctive in terms of color and morphology, and is probably globally endangered because it lives in just three highly vulnerable marshes in central Mexico. This work is part of the Barker lab’s ongoing NSF-funded efforts to resolve a species-level phylogeny for all wrens, an ancient Western hemisphere group that is an important focus for research on vocal and social behavior in birds.
The genetic resources collection is linked to the Biodiversity Atlas. This means that if tissues exist for a particular specimen in the collections, people around the world working on projects can see this, email curators about their project, and ask for the information they need—like the type of tissue and collection conditions, for example. Then curatorial staff will pull out the specimen, cut a subsample, and send it to that researcher. The researcher can then extract the DNA and do whatever work they’re doing. Any data produced from those samples (for example, genomes or specific gene sequences) will be linked forever to the Bell Museum voucher by its unique specimen number.
Minnesota Biodiversity Atlas
The Minnesota Biodiversity Atlas is a searchable, public map showing where Bell Museum animal, plant, and fungal specimens have been found and collected. The Atlas focuses on Minnesota, the meeting place of three of the world’s largest terrestrial ecosystems: eastern broadleaf forests, tallgrass prairies, and coniferous forests. It also represents moments in history before key changes occurred to the landscape, environment, and climate.
What’s most exciting, scientists will use the data in the Atlas to forecast where ecosystems and their associated species may be found in the future.