This project will involve investigators from eight institutions working to resolve evolutionary relationships within the euteleost fishes, which represent over one third of vertebrate diversity. An important component will be education of the public on the importance, evolutionary history, and diversity of these animals. Phylogenetic analyses will employ DNA sequence data from 20 genes in 1,500 species representing all euteleost families, and approximately 450 morphological characters from 300 euteleost lineages. Resulting phylogenetic hypotheses will be used to facilitate understanding of the evolution of fish diversity and re-assess and revise the systematics of euteleosts. Research on the euteleost tree of life will be integrated into science education by using euteleost phylogeny as a framework for exploring the evolution of morphological, genetic, developmental, and behavioral diversity of fishes. This will be developed as an instructional guide, a "Fish ToL Activity Book," directed at upper elementary and middle school children and disseminated in non-formal and school settings working in partnership with the National Science Teachers Association Press and the National 4-H Afterschool Council. Undergraduates, graduate students, and postdocs will participate directly in the research project.
The euteleosts include some 346 families, 2,935 genera and 17,419 species. Over two thirds of all fishes and nearly a third of all vertebrates are euteleosts, which include most of the economically important fishes such as salmons, basses, cods and tunas. This study will facilitate informed predictions about the poorly known characteristics of most euteleosts and will considerably improve the evolutionary context for understanding model organisms such as zebrafish, pufferfish, cichlids, medaka, and stickleback, which are central to the burgeoning fields of functional genomics, genetics and evolutionary developmental biology.
Fish account for over half of vertebrate species, and all vertebrates evolved from fishes. But unlike major groups in vertebrates such as mammals, birds, and reptiles, knowledge about relationships among the major groups of fishes has been hard to come by. As a consequence, the huge diversity of form and habit among fishes has been challenging to explain from an evolutionary perspective on the basis of morphological features alone. Using new molecular evidence (DNA sequences), especially collected from a large number of species to provide a rich record of historical information, the EToL team has been able to stitch together many loose branches in the tree of life of bony fishes. A major result of this research has been to establish a well-supported genealogy of all living fish groups, providing unprecedented levels of resolution among forms that have been historically difficult to classify. The intellectual merit of this project resides in the design of an informative set of more than twenty molecular markers, carefully chosen by comparing whole genomes of a few model fish species, that can be used widely across the diversity of fishes to establish their genetic affinities. Using these markers, DNA data were collected for over 1400 fish species deliberately sampled to represent their vast diversity (it is estimated that there are about thirty thousand fish species). Analysis of this new evidence led to unprecedented resolution of phylogenetic relationships among species. The resulting "family tree" explains the relationship among more than 370 families (out of about 500 currently recognized) included in the study. While some of the findings provided further support for previously understood relationships, others significantly changed existing ideas about fish relationships. Many surprising, unexpected and even strange groupings are proposed in this new tree. For example, fish commonly known as jacks –typically sleek, shiny and fast open-water fish– are identified as the closest relatives of flatfishes, which are bottom-dwelling and have distinctive asymmetric heads. Another unexpected group of closely related species includes disparate forms such as tunas and seahorses. These results led to a new classification for all fishes. This new classification will certainly produce a broad impact beyond ichthyology, especially on disciplines that deal in any way with the diversity of fishes, including fishery sciences and conservation. The standardized new names and classification scheme are available online (www.deepfin.org), and have been already adopted by public databases such as FishBase and Paleobiology. Efforts to extend the use of the new classification continue after the life of this project. Several undergraduate, graduate and postdoctoral students have been trained and were active participants in the course of this research.
