New technique for genetic sampling of salt marsh rats and other small mammals

Study of endangered mice shares offline sampling method

A salt marsh harvesting mouse walks through a sedge in the Grizzly Island wildlife area in San Francisco. Credit: Cody Aylward/UC Davis

From badger species to moles, shrews and mice, many of the world’s endangered mammals are tiny. Genetic sampling is important for understanding how populations are maintained and protected. But finding effective, non-invasive ways to collect genetic samples from young animals can be challenging.

A study from the University of California, Davis, describes a new, non-invasive technique for genetic scanning of the endangered salt marsh harvester mouse, which lives only within the tides. the marshes From the mouth of the San Francisco Bay.

In large mammals, scientists often collect samples from feces, but feces small animals They can be so small that they are difficult to detect in the wild.

New technology published in Mammalology Journal, uses a combination of bait stations and genetics to sample and identify salt marsh harvest mice, or “salt” as the researchers affectionately call them. This species has lost more than 90% of its habitat due to development and is also threatened by sea level rise. That is why it is necessary to accurately and efficiently identify the remaining populations, the authors note.

Study of endangered mice shares offline sampling method

There is a bait station above the flooded tidal swamp of Corte Madeira. This Bay Area swamp bait station attracts but does not trap endangered salt marsh harvest rats, allowing scientists to collect faeces for genetic sampling without the risk of harming mice or other visiting animals as the tidal waters rise and fall. Credit: Cody Aylward/UC Davis

Eat and rush

The technique is simple: bait boxes for scientists with a snack of seeds, millet and oats, and lay out cotton bedding. Mice are free to come and go. The researcher returns a week later to collect stool pellets for genetic sampling in the laboratory. There, a unique species identification test distinguishes the samples of salt marsh harvest mice from those of other rodents that may have used the bait box.

Compare this process with the most common and intensive live trap method: a team of three to five researchers examine the traps at sunrise and sunset for several days in a row. To prevent animal drowning, these traps should be placed above the tide line, excluding several areas of tidal swamp habitat. But with this new, non-invasive technology, mice can leave at any time, allowing researchers to monitor more swamps and more mice safely and efficiently.

“Our method for genetic identification is simple, inexpensive and can be adapted to other small mammal systems,” said lead author Cody Aylward, a recent graduate and former doctoral student in the Mammal Environment and Conservation Unit at the University of California, Davis’ School of Veterinary Medicine. “I hope someone studying a small endangered animal somewhere will read this study and say, ‘This is something I can do. “

Study of endangered mice shares offline sampling method

The endangered salt marsh harvest mouse is endemic to the San Francisco Bay Area and is easily confused with the western bountiful harvest mouse. Credit: William Thein

little wonder

Little is known about salt marsh harvesting mice, so the implications of their potential loss are also unclear. Scientists know the species is unusual in many ways. For example, saltpeters are strong swimmers, can drink sea water and have a unique genetic lineage, Aylward explains:

“The genetic data says that there is a difference of 3.5 million years between them and their closest relatives,” he said. “So if we lose them, that 3.5 million years of evolutionary history is lost.”

Co-authors are principal investigator Mark Statham, Robert Grahn and Benjamin Sachs from the University of California, Davis School of Veterinary Medicine. Douglas Kilt of the Department of Wildlife, Fish and Conservation Biology at the University of California, Davis; and Lauren Barthman-Thompson of the California Department of Fish and Wildlife.


New key to species identification in salt marsh harvest mice


more information:
Cody Aylward et al, A new non-invasive genetic scanning technology for small mammals, Mammalology Journal (2022). DOI: 10.1093/jmammal/gyac070

the quote: A New Technology for Genetic Sampling of Salt Marsh Harvest Mice and Other Small Mammals (2022, September 19) Retrieved September 19, 2022 from https://phys.org/news/2022-09-genetic-sampling-technique-salt-marsh. programming language

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