Genetic Innovations Underpin Morphological Diversity and Radiation in Teleost Fish

Abstract

Teleosts, the most species-rich group of jawed vertebrates, have evolved a remarkable diversity of primitive and specialized features that provide a valuable resource for understanding vertebrate evolution. Here, we collected a comprehensive genome dataset of fish, including 115 newly sequenced species, to fill genome gaps for seven orders. By combining the phylogenetic and fossil records of teleosts, we observed that they were relatively scarce from the early to middle Triassic but quickly flourished following the massive extinction event at the end of the Triassic. This rapid radiation coincided with global temperature increases and the fragmentation of Gondwana, implying a positive correlation between temperature rise, tectonic plate movements, and teleost radiations. Our data also revealed that the end-Triassic extinction event had a greater impact on teleost radiation than the Permian-Triassic extinction. We identified a core set of regulatory elements related to aquatic adaptation traits such as swim bladder functional shift and structural specialization of pectoral fin, which were crucial for the adaptation of teleosts to their broad ecological niches. Functional experiments validated the regulatory roles of these conserved elements on the formation of specialized homologous organs in teleosts. Overall, our findings shed light on the links between teleost speciation bursts with geological events, and genetic innovations that have shaped extant teleost biodiversity.