Comprehensive phylogenomic analyses resolve cnidarian relationships and the origins of key organismal traits
- Published
- Accepted
- Subject Areas
- Evolutionary Studies
- Keywords
- Cnidaria, Anthozoa, Staurozao, Scyphozoa, Cubozoa, Hydrozoa, Acraspeda, Hexacoralia, Octocoralia, Ceriantharia
- Copyright
- © 2017 Kayal et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Comprehensive phylogenomic analyses resolve cnidarian relationships and the origins of key organismal traits. PeerJ Preprints 5:e3172v1 https://doi.org/10.7287/peerj.preprints.3172v1
Abstract
The phylogeny of Cnidaria has been a source of debate for decades, during which nearly all-possible relationships among the major lineages have been proposed. The ecological success of Cnidaria is predicated on several fascinating organismal innovations including symbiosis, colonial body plans and elaborate life histories, however, understanding the origins and subsequent diversification of these traits remains difficult due to persistent uncertainty surrounding the evolutionary relationships within Cnidaria. While recent phylogenomic studies have advanced our knowledge of the cnidarian tree of life, no analysis to date has included genome scale data for each major cnidarian lineage. Here we describe a well-supported hypothesis for cnidarian phylogeny based on phylogenomic analyses of new and existing genome scale data that includes representatives of all cnidarian classes. Our results are robust to alternative modes of phylogenetic estimation and phylogenomic dataset construction. We show that two popular phylogenomic matrix construction pipelines yield profoundly different datasets, both in the identities and the functional classes of the loci they include, but resolve the same topology. We then leverage our phylogenetic resolution of Cnidaria to understand the character histories of several critical organismal traits. Ancestral state reconstruction analyses based on our phylogeny establish several notable organismal transitions in the evolutionary history of Cnidaria and depict the ancestral cnidarian as a solitary, non-symbiotic polyp that lacked a medusa stage. In addition, Bayes factor tests of multiple origins strongly suggest that symbiosis has evolved multiple times independently across the cnidarian radiation. Cnidaria have experienced more than 600 million years of independent evolution and in the process generated an array of organismal innovations. Our results add significant clarification on the cnidarian tree of life and the histories of these innovations. Further, we confirm the existence of Acraspeda (staurozoans plus scyphozoans and cubozoans), thus reviving an evolutionary hypothesis put forward more than a century ago.
Author Comment
Manuscript has been submitted to a peer-reviewed journal.