title: Employing Phylogenomics to Resolve the Relationships among Cnidarians, Ctenophores, Sponges, Placozoans, and Bilaterians.
abstract: Despite an explosion in the amount of sequence data, phylogenomics has failed to settle controversy regarding some critical nodes on the animal tree of life. Understanding relationships among Bilateria, Ctenophora, Cnidaria, Placozoa, and Porifera is essential for studying how complex traits such as neurons, muscles, and gastrulation have evolved. Recent studies have cast doubt on the historical viewpoint that sponges are sister to all other animal lineages with recent studies recovering ctenophores as sister. However, the ctenophore-sister hypothesis has been criticized as unrealistic and caused by systematic error. We review past phylogenomic studies and potential causes of systematic error in an effort to identify areas that can be improved in future studies. Increased sampling of taxa, less missing data, and a priori removal of sequences and taxa that may cause systematic error in phylogenomic inference will likely be the most fruitful areas of focus when assembling future datasets. Ultimately, we foresee metazoan relationships being resolved with higher support in the near future, and we caution against dismissing novel hypotheses merely because they conflict with historical viewpoints of animal evolution.
authors.affiliation: *Department of Biological Sciences, Molette Biology Laboratory for Environmental and Climate Change Studies, Auburn University, 101 Life Sciences Building, Auburn, AL 36849, USA; nwhelan@auburn.edu.
authors.forename: Nathan V
authors.initials: NV
authors.lastname: Whelan
authors.affiliation: School of Biological Sciences, The University of Queensland, 325 Goddard Building, St Lucia, QLD 4101, Australia.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Kocot
authors.affiliation: *Department of Biological Sciences, Molette Biology Laboratory for Environmental and Climate Change Studies, Auburn University, 101 Life Sciences Building, Auburn, AL 36849, USA;
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Halanych
mesh_terms: D000818:Animals; D003063:Cnidaria / Q000145:classification / Q000235:genetics; D037302:Ctenophora / Q000145:classification / Q000235:genetics; D007448:Invertebrates / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D054909:Placozoa / Q000145:classification / Q000235:genetics; D011161:Porifera / Q000145:classification / Q000235:genetics