An international team of researchers has sequenced the largest genome of any animal, that of the lungfish, revealing significant insights into vertebrate evolution.

The immense size of the lungfish genome is largely due to autonomous transposons, which make up over 90% of its genetic material and contribute to its rapid expansion.

Remarkably, eighteen of the nineteen chromosomes of the South American lungfish are individually larger than the entire human genome.

This genomic research highlights how lungfish, particularly from Africa and South America, have undergone significant changes, including reduced limb-like fins.

The study indicates that the lungfish's lung development shares genetic origins with land vertebrates, including humans, illustrating a deep evolutionary connection.

The simplification of fins in African and South American lungfish is linked to changes in the Shh-signaling pathway, which plays a crucial role in digit development in vertebrates.

The lungfish genome helps explain how the fish ancestors of land vertebrates successfully transitioned to terrestrial life.

Lungfish are considered the closest living relatives of the first vertebrates that transitioned to land around 400 million years ago.

This evolutionary journey traces back to the Devonian period, approximately 420 to 360 million years ago, when lobe-finned fishes began moving onto land.

Today, three lungfish lineages exist: one in Africa, one in Australia, and one in South America, particularly in the Amazon basin, all of which have remained relatively unchanged over time.

Key references in this research include works by Meyer et al. and Wang et al., which discuss lungfish genomes in the context of vertebrate evolution.