The widespread transfer of genes between species seems to be the main driver of evolution

July 9, 2018

Far from simply being the product of our parents, scientists from the University of Adelaide have shown that the widespread transfer of genes between species has changed dramatically the mammalian genomes of today.

In the world's largest study of "jumping genes," researchers traced two particular jump genes in 759 species of plants, animals, and fungi. These jumping genes are actually small fragments of DNA that can be copied into a genome and are known as transposable elements.

They found that interspecific transfers, even between plants and animals, occur frequently during evolution. The two transposable elements that they have plotted – L1 and BovB – have entered mammals as foreign DNA. This is the first time that anyone has shown that the L1 element, important in humans, has jumped between species.

"Jumping genes, called retrotransposons, copy and glue around genomes and genomes of other species, not yet known, even if insects such as ticks or mosquitoes or possibly viruses can be involved – it's still a big headache, "says Professor David Adelson, director of the bioinformatics center at Adelaide University .Transfer, different from normal transfer parent-offspring, and it has had a huge impact on the evolution of mammals. "

For example, Professor Adelson says, 25% of the genome of cows and sheep is derived from jumping genes.

"Think of a gene jumping as a parasite," says Professor Adelson. "What's in the DNA is not so important – it's the fact that they show up in other genomes and cause gene disruption and how they are." regulated. "

Posted today in the journal Genome Biology in In collaboration with the South Australian Museum, the researchers discovered that horizontal gene transfer was far more prevalent than one does. thought.

"It was thought that L1 elements were inherited only from parents to descendants," says Dr. Atma Ivancevic, a postdoctoral researcher at the Adelaide University School of Medicine. "Most studies have examined only a handful of species and found no evidence of transfer, we examined as many species as possible."

L1 elements in humans have been badociated with cancer and neurological disorders. Researchers say that understanding the heredity of this element is important to understanding the evolution of diseases.

Researchers have found that L1 are abundant in plants and animals, although they only appear sporadically in fungi. But the most surprising result was the lack of L1 in two key mammalian species – Australian monotremes (platypus and echidnae) – showing that the gene entered the mammalian evolutionary pathway after the divergence of monotremes.

"We believe that the entry of L1s into the mammalian genome has been a key factor in the rapid evolution of mammals over the last 100 million years," says Professor Adelson

The team also examined the transfer of BovB elements between species.BovB is a much younger jumping gene: it was first discovered in cows, but it has since been demonstrated that He was jumping between a bizarre range of animals, including reptiles, elephants and marsupials.Anterior research, conducted by Professor Adelson, showed that ticks were the most likely facilitators of BovB transfer. inter-species

New research has extended the badysis to find that BovB has jumped even more widely than expected.BovB has transferred at least twice between frogs and bats, and new potential vector species they include bed bugs, leeches and locusts

The team believes that studying insect species will help find more evidence of inter-species transfer. They also aim to study other jumping genes and explore the possibility of aquatic vectors, such as sea worms and nematodes.

"Although our recent work involved the badysis of genomes of more than 750 species, we have only begun to scratch the surface of horizontal gene transfer," says Professor Adelson. "There are many more # 39; species to study and other types of gene jumpers. "