Nearly a hundred genes have been lost during the evolution of the woolly mammoth
A new study shows that 87 genes have been affected by deletions or short insertions over the course of mammoth evolution. The researchers note that their findings have implications for international efforts to bring extinct species, including the woolly mammoth, back to life. The study is published today in the journal iScience by researchers from the Center for Palaeogenetics in Stockholm, a collaboration between Stockholm University and the Swedish Museum of Natural History.
One of the most discussed methods of bringing extinct species back to life is to use genome editing techniques such as Crispr-Cas9 to insert key gene variants from an extinct species into a genome of its living relative. However, the results in this new study indicate that it may also be necessary to delete certain genes to preserve important biological properties while reconstructing extinct genomes.
“Editing the genome of a living species to mimic that of an extinct relative would never be easy, and these new findings certainly illustrate the complexity and difficulties ahead,” said Love Dalén, a professor of evolutionary genomics at the Center for Paleogenetics.
The researchers behind the study sequenced two new genomes of the Siberian mammoth from the last Ice Age and compared them with a total of 33 previously published genomes of mammoths, Asian elephants and African elephants.
Losing part of a gene, a deletion of a gene, will affect its function. Likewise, short insertions lead to frame-shift mutations that can render the genes unreadable. The results show that there are many thousands of deletions and short insertions in the mammoth’s genome, comprising more than three million letters in the genetic code. Overall, the researchers found that most of these were not in genes, indicating that they generally had a negative effect on mammoth viability.
“However, we also found 84 genes affected by genomic deletions and three affected by short insertions. These structural changes likely had a significant impact on the function of these genes and may have contributed to some of the woolly hair’s unique adaptations.” mammoth,” says Tom van der Valk, researcher at the Center for Paleogenetics.
The change in functionality in these 87 genes may have been important to mammoths as they evolved adaptations to the cold environment of the far north. Many adaptive traits, such as body size and cold tolerance, are regulated by different genes. Loss of some of these genes may therefore affect the functional pathways that shape the development of these adaptive traits.
“Several genes affected are related to classic woolly mammoth traits, such as coat growth and hair shape, fat deposition, as well as skeletal morphology and ear shape,” said Marianne Dehasque, a Ph.D. student mammoth genomics at the Center for Paleogenetics.
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Tom van der Valk et al, Evolutionary consequences of genomic deletions and insertions in the woolly mammoth genome, iScience (2022). DOI: 10.116/j.isci.2022.104826
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