Phylogeny

Modern fish phylogenomics uses thousands of nuclear gene loci simultaneously (via target capture or whole-genome sequencing) to reconstruct relationships with unprecedented resolution. The Near et al. (2012) and Betancur-R et al. (2013) studies revolutionized teleost phylogeny, revealing that Perciformes — previously the largest vertebrate order — is polyphyletic, requiring subdivision into multiple new orders. Divergence dating using molecular clocks calibrated against fossils shows that many modern fish lineages originated after the K-Pg extinction event 66 million years ago, exploiting ecological opportunities vacated by marine reptiles.