Scientists have successfully sequenced the genome of the South American lungfish, a primordial air-breathing fish that has existed for hundreds of millions of years. The genome is an astonishing 30 times larger than the human genome, clocking in at 91 billion base pairs.
The study published in Nature found that the majority of the genetic material is made up of transposable elements (TEs), or “jumping” genes that were copied from elsewhere in the genome. This massive expansion of DNA code over the past 100 million years has allowed the lungfish to adapt to changing environments, according to evolutionary biologist Axel Meyer.
The findings also shed light on how genomes expand across the tree of life. The researchers discovered key genes that suppress TEs, which organisms may have inherited from viruses long ago.
While carrying around such genetic baggage can be problematic, it can also come in handy when animals need to adapt to changing environments. The extra DNA allows for more rapid adaptation through the up or down regulation of gene expression.
The South American lungfish holds the record for the largest known animal genome, but there may be other contenders waiting to be sequenced. The marbled lungfish, for example, may have a genome 50% larger than this one.
Source: https://www.livescience.com/health/genetics/largest-animal-genome-sequenced-and-just-1-chromosome-is-the-size-of-the-entire-human-genome