New research is questioning our understanding of how genetic information is passed on. We tend to think of genetic material as being transferred ‘vertically’, from parent to child down generations within a species. However, it appears that a significant proportion of genetic material in humans and other animals ‘jumps’ from other species—transferring ‘horizontally’. This foreign DNA can be a significant factor in how species evolve. Scientists already knew that genetic material could be transferred horizontally between bacteria; in fact, this is how bacteria infecting humans are able to quickly develop resistance to antibiotics. Until now, however, the extent and role of this mechanism in humans and other animals was unclear.
So how does this all work? Firstly, this foreign genetic material isn’t genes as such but non-coding genetic elements that fill the spaces between genes. These transposable gene elements make up over half of our genome, and yet we still know little about them and what they do. According to Atma Ivancevic, lead author of a study published on this topic, this genetic material seems bent on replicating itself as much as possible. By looking for traces of two types of transposable elements, Bovine-B (BovB) and L1, researchers aimed to track them and see how, and how far, they spread. They found that some BovB material had hopped multiple times between frogs and bats, probably originating in snakes, and makes up about a quarter of the genome of cows and sheep. L1s were also found to be present in many animal and plant species.
So if this genetic material isn’t transferred through reproduction, how does it operate? A crucial clue came when Ivancevic and her team found such material present in parasitic creatures such as leeches and ticks, which strongly suggested that transposable genetic elements were introduced to the DNA of various species using parasites as their vehicles of dispersion. Although being ‘foreign’, transposable elements are not necessarily all bad news; although admittedly L1s may have links to cancer and neurological disorders, other gene elements are likely to be beneficial, and others still appear to do nothing at all. “We have evidence that they are doing good and bad things, almost accidentally,” says Ivancevic.
Applicants for Biology or Natural Sciences should familiarise themselves with recent developments in evolutionary biology, as well as being well-versed in the fundamentals. How does research such as this add to our understanding of evolution and the role of genetics?