To learn more about humans, a large international team of scientists has tracked some of the strangest creatures on the planet for years. They camped on an Arctic ice floe and took his DNA from a single tusk. Narwhala small net bumblebee bat In the cave-rich region of Southeast Asia, I stepped behind the scenes at a Caribbean zoo to draw the blood out of my slender nose. Solenondonone of the few poisonous mammals in the world.
The researchers compared the genomes of these mammals to those of other mammals of various species, including aardvarks, meerkats, star-nosed moles, and humans. In doing so, they were able to identify stretches of DNA that have changed little over the years of mammalian evolution and are therefore likely to be essential for human health and function.
Their compiled genetic database contains the complete genomes of 240 species, covering over 80% of all mammals (and humans included) on Earth. This could help scientists answer a variety of questions about other animals. For example, when and how animals evolved and the biological basis for their extraordinary talents.
“What’s the most amazingly cool thing those species can do that humans can’t?” Geneticist at UMass Chan Medical School and Broad Institute zoonomia project“We always think of humans as the most special species. But we’ve found them very boring in many ways.”
The Zoonomia dataset has limitations. It contains only one genome per species (with the exception of domestic dogs, which have been sequenced twice), and thousands of mammals are missing.
But in a new series of papers published Thursday in Science, the Zoonomia team showed the power of this kind of multispecies data. And that’s just the beginning.
“Sequencing a lot of genomes is no small feat,” says Michael G. Campana, a computational genomics scientist at the Smithsonian’s National Zoo and Conservation Biology Institute, who said the project did not participate in “What really matters is putting these data to practical use.”
Here are some of the things Zoonomia scientists are already doing with it.
Revealing the basics of special skills
To look for the basis of an animal’s extraordinary talents, scientists looked for gene sequences that evolved abnormally rapidly in species that shared certain traits, such as the ability to hibernate.
of one analysis, researchers focused on deep-hibernating animals such as thick-tailed dwarf lemurs and bats, which can maintain low body temperatures for days or weeks at a time. The researchers found evidence of ‘evolutionary acceleration’ in a variety of genes, including genes known to help protect cells from temperature-related stress and genes that inhibit cellular pathways associated with aging. discovered.
“Many hibernating species live exceptionally long,” Dr. Karlsson says.
The researchers also investigated mammalian sense of smell. Animals have a large number of different olfactory receptors, each of which can bind to specific odor-causing molecules. Species with more olfactory receptor genes generally have a more acute sense of smell.
When the Zoonomia team tabulated the number of these genes by species, the African savannah elephant took the top spot with 4,199. Nine-band Armadillo and Hoffmann’s his two-toed sloth followed, with Agouti of Central America taking his fourth place.
Agouti “turns out to have one of the best olfactory repertoires of any mammal, for reasons that are completely unknown,” says Dr. Karlsson. “It’s a reminder that there’s a diversity out there that we don’t know anything about.”
On the other hand, Cetaceans, a group that includes dolphins and whales, have significantly fewer olfactory receptor genes. “They communicate in different ways,” says Kirsten Lindblad, a geneticist at the Broad Institute and Uppsala University and another leader of the Zoonomia project.
Species with more olfactory receptor genes also tended to have more olfactory turbinates, the bony structures in the nasal cavity that aid in olfaction. The results suggest that “when certain traits are important, they evolve in multiple ways,” Dr. Lindblad-Toh said.
“I think one of the important things about our dataset is that we can generate genome sequences for so many different species and people can start looking for their favorite traits.”
paint a group portrait
In February 1925, during a diphtheria epidemic, a relay dog sled team delivered an emergency supply of antivenom to a snow-strapped Nome, Alaska state. Balto, one of his dogs who ran the final leg of the relay, became famous. When he died a few years later, his taxidermied body was displayed at the Cleveland Museum of Natural History.
Zoonomia’s team of researchers used small pieces of its taxidermy tissue to Learn more about celebrity sled dogs and his dog contemporaries. “I thought this was a bit of a challenge,” said her Kathleen Morrill, author of the Balto paper, who did the research as a graduate student at UMass Chan Medical School and is now a senior scientist at his Colossal Biosciences. increase. “This is one really famous person. We don’t know much about his biology. What can we say about his genome?”
They found that Baltos were genetically “healthier” than modern purebred dogs, passing on more genetic mutations and fewer potentially harmful mutations. , which may stem from the fact that sled dogs are typically bred for physical ability and may be of mixed breeds.
Researchers found that Balto had various genetic mutations that were not present in wolves and rare or absent in modern purebred dogs. Many variants are in genes involved in tissue development and may have affected various traits important to sled dogs, such as skin thickness and joint formation. Balto had two copies of her of these mutants, inheriting one of him from each parent. This meant that they were at least somewhat common among other Alaskan sled dogs of the time.
“It gives us a clearer picture of who he is and what his population looks like,” said study author Katie Moon, a postdoctoral fellow at the University of California, Santa Cruz. “And that picture is of a working sled dog that is really well adapted.”
Illuminate the evolutionary timeline
Scientists have long debated when and how today’s diverse mammals originated. Did the mammalian family tree diverge after the extinction of the dinosaurs some 66 million years ago, or did the process largely take place before the catastrophe?
a New analyzes with zoonotic genomes The answer suggests both.Mammals first began to diversify About 102 million years ago, when the Earth’s continents broke apart and sea levels began to rise. “This segregated the predecessors of modern lineages to different land masses,” says study author William Murphy, an evolutionary geneticist at Texas A&M University.
But after the dinosaurs went extinct, new lands emerged and the disappearance of living reptiles brought new habitats, resources and opportunities for mammals, further diversifying them, researchers say. discovered.
“This is a really groundbreaking paper,” said Scott Edwards, an evolutionary biologist at Harvard University, who was not involved in the study. “This is probably the largest of its kind in terms of fitting mammals to the timescale.”
The Zoonomia package is more broadly a “monumental body of work,” he added. “This will set the standard for understanding mammalian evolution going forward.”
Extinction risk prediction
Mammals normally inherit two copies of most gene sequences, one from each parent. By determining how well these sequences match, we can get an idea of the size of past animal populations. For example, long stretches of matching DNA could be a sign of inbreeding.
Allin Wilder, a conservation geneticist at the San Diego Zoo and Wildlife Alliance, says that a single animal’s genome reflects “how closely its parents, grandparents were related all along.”
Dr. Wilder and colleagues Using the zoonomia genome Estimate populations of various species throughout history. Species that were historically low in population relative to historically high abundance may carry potentially harmful genetic mutations and be classified as threatened with extinction. I got taller. International Union for Conservation of Nature.
The researchers also analyzed the genomes of three species that the IUCN deemed of unknown extinction risk due to lack of data. Killer Whale, Blind Mobar Rat of Upper Galilee, Javan Deer (looks exactly as advertised). The results suggested that killer whales may be most at risk.
Beth Shapiro, a paleogeneticist at the University of California, Santa Cruz, and study author, said the approach offers a rapid way to prioritize species for more thorough and resource-intensive risk assessments. said it could be done. “It might be a relatively easy way to do conservation triage,” she said.
