Power of Genetics
DNA Forensics Help Solve Wildlife Crimes, Conserve Species
Photo: Rebecca N. Johnson
Genomics can help solve animal cruelty cases, prosecute wildlife crimes and conserve endangered species, said Dr. Rebecca Johnson, member of the Order of Australia and chief scientist at the Smithsonian National Museum of Natural History.
“DNA can really be a valuable tool for fighting wildlife crime when combined with museum collections,” said Johnson during the recent Louise M. Slaughter National DNA Day lecture.
The annual lecture honors the life and legacy of the late New York congresswoman, who was a strong advocate for genomics research. She was also responsible for passing the 2003 resolution in the U.S. House of Representatives that created National DNA Day. NHGRI established the Slaughter lecture in 2018.
In 2004, Johnson worked as a DNA laboratory manager at the Australian Museum, one of the world’s oldest natural history museums, in Sydney, Australia. The museum contains millions of specimens from a vast number of countries around the globe and thousands of frozen genomic samples.
That same year, police asked for her help solving an allegation of animal cruelty. A man was accused of intentionally driving his car through a flock of cockatoos. After the incident, police found blood under the man’s car, but they had no way of determining what animal the blood came from. The officers called Johnson.
“I thought, as a geneticist, I could certainly help with this identification,” she said. “Working at the Australian Museum, I had plenty of access to cockatoos that I could use as reference samples.” A detailed DNA analysis revealed the blood indeed was cockatoo.
Johnson has since analyzed many samples linked to wildlife crime, a fast-growing, multi-billion-dollar industry. Her background allows her to give authorities genetic data that provides evidence in court.
In one instance, her forensics lab developed a DNA test for the species identification of rhino horns. The greatest threat to these animals is poaching their horns for illegal trade. Rhinos are being killed faster than they can reproduce.
There are 5 species of rhinoceros—2 are endemic to Africa and 3 are native to Asia. Johnson said identifying where the horn originated is very important “if you’re trying to prosecute a case based on where it might have come from or get intelligence as to what species is being targeted by poachers.”
Her lab shared the testing method with several countries in southeast Asia because trade in rhino horns is higher in that part of the world. Several nations used the test before she could publish her results, a circumstance she described as both encouraging and depressing, because there’s such a high demand for such testing.
Johnson’s lab also developed a DNA test to track the source of echidnas in the illegal wildlife trade. Echidnas are egg-laying mammals native to Australia and a few countries in southeastern Asia.
Photo: Rebecca N. Johnson
Each year, more than 150 “captive-bred” echidnas are offered for sale to zoos and other collecting institutions. However, these animals are notoriously difficult to breed in captivity. Within the past 10 years, only 30 baby echidnas, or puggles, were born in Australian zoos.
“The equation didn’t fit that 150 captive-bred animals were being sold,” she said. “We thought this might be worth investigating. We worked with several zoos who really, really wanted to make sure they were sourcing their animal from ethical and legal sources.”
In some instances, trafficking of a species declines once it’s known there is a DNA test for that species. Johnson isn’t sure if echidna trafficking has declined yet.
Australia has one of the worst extinction rates in the world. Since Europeans settled the country in 1788, more than 10 percent of Australian land mammals have gone extinct. One of the most famous examples is the thylacine, also known as the Tasmanian tiger, the last of which died on Sept. 7, 1936, in captivity.
“It’s a reminder that you can’t just sit by and watch. Intervention needs to happen well before you’re looking at the last animal,” Johnson warned.
Photo: Credit Greta Frankham
As the climate gets hotter and urban development further encroaches on forested areas, many species are at risk for extinction, including red-tailed cockatoos and koalas.
Red-tailed cockatoos inhabit savannahs, deserts, temperate forests and woodlands across Australia. These large iconic cockatoos nest in hollows inside old trees. Unfortunately, these older trees are disappearing due to change in land use (land clearing) and climate change. This has decimated the bird species population in certain areas.
Thanks to genomics, Johnson and her team have identified new cockatoo subspecies. This means her group can determine which subspecies are most at risk. In a southern area of Australia, for instance, one subspecies has fewer than 1,000 birds. This means conservationists can direct resources at conserving that population.
Another iconic Australian species, the koala, is under threat from habitat loss, climate change and disease. Over the next 15 years, several koala populations are projected to decline by up to 53 percent in some areas.
A few years ago, Johnson and a team of experts successfully sequenced the koala genome, which has revealed important information about their diet and genetic diversity. The data was integrated into a plan to conserve the species.
A koala’s diet consists primarily of leaves from toxic eucalyptus species. They are essentially “super-detoxing” organisms. Johnson explained, “They’re one of the very few animals that has been able to specialize, to eat something that’s not just unpalatable to most other species, but deadly in high enough quantity.”
Understanding how koalas metabolize eucalyptus leaves has implications for veterinary care.
Some koala populations in Australia vary in genetic diversity. The population in the north is very diverse, while the population in the south is abundant, but inbred. “This is not a great practice to perpetuate,” she said. “There’s a lot of discussion about how this might be handled going forward.”
Now at the Smithsonian, Johnson is working hard to develop the museum’s genomics department. “We have an extremely active genomics community and are specializing our environment that maximizes our ability to extract valuable information from museum collections, so we can be good contributors and collaborators to the knowledge of biodiversity,” she concluded.