New analysis of rare Argentinian rat unlocks origin of the largest mammalian genome
New biological information gleaned from the red vizcacha rat, a native species of Argentina, demonstrates how genomes can rapidly change in size. Red vizcacha rat, a rare species found in Argentina [Credit: McMaster University] Researchers from McMaster University set out to study this particular species because its genome, or its complete set of DNA, is the largest of all mammals, and appears to have increased in size very rapidly. The rat's genome is roughly two-and-a-half times as large as the human genome, including 102 chromosomes versus 46 for humans, and is about twice as large as one of its closest relatives, the mountain vizcacha rat. The most recent common ancestor of these species existed only about five million years ago. "This genomic transformation is striking because it happened over a very short period of time in evolutionary terms," says Ben Evans, a biologist at McMaster and lead author of the new research published in the journal Genome Biology and Evol