A genomic compendium of hundreds of teleost fishes reveals their evolutionary landscape

The remarkable morphological diversity and species abundance of teleost fishes offer a valuable resource for understanding vertebrate evolution. In phase I of the Fish10K project, genomes of 110 teleost species were sequenced and assembled, filling gaps in 3 previously unrepresented orders, and integrated with existing data to generate a 464 species whole-genome alignment spanning all teleost orders-the largest such resource beyond mammals and birds. Comparative analyses reveal distinctive genomic features, including progressive genome compaction with shortened intron lengths relative to non-teleost ray-finned fishes. Analysis of the transposable element (TE) landscape suggests a potential association between TE expansion in teleost genomes and different habitats, as well as the uniqueness of teleosts' DNA-dominated transposon composition among vertebrates. Genome-wide phylogenetic analyses refute the widely accepted monophyly of "Siluriphysi" hypothesis and support the hypothesis of a single origin of electroreception followed by secondary loss in Characiformes. A refined evolutionary timeline of teleosts by whole-genome alignment resource placed teleosts at ∼253 million years ago, predating the Permian-Triassic extinction, and delineates three diversification phases punctuated by mass extinctions, challenging continuous post-Cretaceous-Palaeogene acceleration models. This study establishes a large-scale genomic database and a foundational whole-genome alignment resource, advancing insights into the landscape of teleost genomic architecture and macroevolution.