BovB: Jumping the fine LINE between species

In higher organisms such as vertebrates, it is generally believed that lateral transfer of genetic information does not readily occur, with the exception of retroviral infection. However, horizontal transfer (HT) of protein coding repetitive elements is the simplest way to explain the patchy distribution of BovB, a LINE (Long Interspersed Nuclear Element) about 3.2kb long, that has been found in ruminants, marsupials, squamates, monotremes and African mammals. BovB sequnces are a major component of some of these genomes. Here we show that HT of BovB is significantly more widespread than believed, and we demonstrate for the first time the existence of two plausible arthropod vectors, specifically reptile ticks. A phylogenetic tree built from BovB sequences from species in all of these groups does not conform to expected evolutionary relationships of the species, and our analysis indicates that at least 9 HT events are required to explain the observed topology. Our results provide compelling evidence from HT of genetic material that has transformed vertebrate genomes.