# South American Lungfish Genome Reaches Record 91 Billion Base Pairs Researchers discover that massive lungfish genomes consist primarily of repetitive, non-functional genetic material. - **Source:** [All Articles | Discover Magazine](https://www.discovermagazine.com/rss/all) - **Published:** 2026-10-30 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/a4cfcdcd-5e1b-4ff5-a1db-0a4a1acd4527 ## Record Breaking Genetic Scale The South American lungfish possesses the largest animal genome ever recorded, containing 91 billion base pairs. This figure is approximately 30 times larger than the human genome, which totals nearly 3 billion base pairs. Despite this massive scale, the lungfish does not exhibit higher biological complexity compared to human beings. ## Evolutionary Context of Lungfish Lungfish are the closest living relatives to tetrapods, the group that transitioned from water to land during the late Devonian period. This transition occurred between 380 million and 360 million years ago. Studying their complete genome provides critical insights into the biological adaptations that enabled early vertebrates to inhabit terrestrial environments. ## Mechanism of Genome Expansion The massive size of the lungfish genome is driven by an abundance of transposons, often referred to as jumping genes. These segments replicate uncontrollably throughout the genome. Research indicates that every 10 million years, the South American lungfish genome expanded by an amount equivalent to the entire size of the human genome. ## Role of piRNA Deficiency The unchecked growth of these transposons is linked to low levels of piRNAs within the lungfish. These ribonucleic acids typically function to limit the spread of transposable elements in an organism. Without sufficient piRNA regulation, these sequences have accumulated over millions of years, leading to the gargantuan genome sizes observed today. ## Composition of Genetic Material Approximately 90 percent of the lungfish genome consists of repetitive DNA sequences, often described as genetic fluff or junk DNA. While these sequences have replicated out of control, they do not necessarily provide functional benefits to the species. The genome remains surprisingly stable despite the high volume of repetitive content present. ## Comparative Genomic Observations Other lungfish species also exhibit significant genome sizes, such as the West African lungfish at 40 billion base pairs and the Australian lungfish at 43 billion. The Marbled lungfish potentially holds an even larger genome of 133 billion base pairs, though this remains unconfirmed as the species has not been officially sequenced. ## Broader Biological Implications Large genomes are not exclusive to lungfish; salamanders and Antarctic krill also possess massive genetic structures filled with repetitive sequences. Research suggests that in some species, these large genomes correlate with larger cell sizes and lower metabolic rates. However, for lungfish, the accumulation is largely considered a result of purposeless evolutionary processes. ## Scientific Significance of Findings The 2024 study published in Nature highlights how genomic sequencing clarifies the evolutionary history of lobe-finned fish. By analyzing these massive structures, scientists better understand the genetic shifts that occurred over the last 100 million years. These findings emphasize that genome size is not a direct indicator of an organism's evolutionary advancement. ## Sources covering this story - https://www.discovermagazine.com/the-largest-animal-genome-belongs-to-a-freshwater-fish-at-91-billion-base-pairs-but-90-percent-is-repeat-dna-49875 — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._