Want to save an endangered species? Start with the right DNA blueprint

When scientists want to trace how a species has changed over time and predict its survival prospects – they turn to DNA. But what happens if the genetic card that guides them belongs to the bad animal?

A study led by researchers from the USC Dornsife College of Letters, Arts and Sciences shows that the use of the bad “reference genome” – the masters of scientists rely to compare DNA – can considerably distort the image. For the gray fox, one of the most common wild canids in North America, mapping a dog or Arctic fox genome, instead of itself, made the populations smaller, less diverse and even declining when they were really stable or growing.

“It turns out that the reference you use really changes the story you tell about a species,” said Jazlyn Mooney, deputy professor of quantitative and computer biology at USC Dornsife and corresponding author of the study published in Cell. “If you use the bad reference, you can end up with misleading answers on the history or the health of a species, and even its long -term chances of survival.”

Scientists have put a reference genome in the test

Each genetic study needs a starting point: a reference genome, generally built by sequencing the DNA of an individual of a species. When scientists study additional people, they align the new DNA against this reference for comparison.

But many species, especially those less studied, do not have their own reference. In these cases, researchers turn to the best following option – a close relative. For decades, the genome of the domestic dog is standing for foxes, wolves and wild dogs.

Mooney and her colleagues wondered how much this choice imported. Would the use of a genetically distant plan simply blur the details, or could it really rewrite history?

The team reanalyzed the DNA of 12 gray foxes – six from the east of North America and six from the west – comparing how their genomes aligned on three different references: the gray fox itself, the domestic dog and the Arctic fox.

They asked:

• What genetic variation appears?
• What do data on past population sizes reveal?
• Do current populations develop or decrease?
• What genes seem to be under natural selection, referring to adaptation?

The answers strongly depended on which genome served as a card.

With the Gray Fox genome, researchers detected 26% at 32% more genetic differences between individuals and approximately a third more rare variants (subtle DNA changes that reveal how populations have changed recently).

Estimates the population size was also 30% to 60% higher. In the western United States, for example, the gray fox genome has shown stability and growth, while the genomes of the dog and the Arctic fox have suggested the decline.

The bad reference also triggered measures of how DNA mixes during reproduction. With the genomes of the dog or the Arctic fox, the figures have sometimes doubled or even tripled compared to the genome of the gray fox, in particular near the ends of the chromosomes.

“This is the kind of thing that could change conservation decisions,” said Mooney. “If you think that a population shrinks when it is not, or vice versa, you could eventually protect the bad group or miss an opportunity to protect genetic diversity.”

The study has also shown that the use of the bad reference could create misleading signs of natural selection. The genomes of the dog and the Arctic fox have identified twice as many potential “hot spots” of DNA – regions which seemed to be adaptive – compared to the genome of the gray fox. Many of these signals were false alarms, caused by the discrepancy between species.

Why the right reference genome is important for conservation and people

The implications of the study go far beyond the foxes. Conservation biologists use genetic data to decide which populations protect, how to design reproductive programs and if endangered species are at risk of consanguinity. If the genetic image is distorted, these decisions can rest on a trembling soil.

This could affect high -level species such as the Ethiopian wolf, the African wild dog or even the tiny foxes of the island of the number off the coasts of southern California. For animals already on the edge, an imperfect card could mean misunderstanding their vulnerability.

“Maintaining the world’s biodiversity is not only to save animals for themselves,” said Mooney. “Biodiversity supports drinking water, food safety and climate stability. If the conservation plans are based on incomplete or biased genetic information, we risk poorly managing species and weakening natural systems on which people depend.”

These results echo a lesson in human genetics: for years, the human reference genome has mainly drawn from a few people, limiting research between populations. More recent efforts are to create references that better reflect global diversity.

Scientists call for better genomic cards

Researchers argue that the solution is to invest in the construction of specific reference genomes. The assembly of a high -quality genome sequence is expensive, and almost 99% of species are not lacking, but the gain could be crucial.

For species without their own reference, Mooney and his team point to new calculation methods and the construction of high quality genomes which more capture the diversity of a species – such as means of reducing biases.

“We do not say that all species will be as affected as the gray foxes,” said Mooney. “But our study shows that the risks are real and can lead you out.”

The Gray Fox study is both a warning and a call for action: choosing the bad reference does not just blur the details – it can redraw the past and the future of a species.