Resolved Phylogeny of the Class Cephalopoda

What We Can Learn

Recent studies of cephalopod genomes have revealed these to be highly informative for understanding the Mollusca development of intelligence, color perception, and nuanced methods of communication. Critical to such insights is a well-resolved phylogeny of this unusual mollusc radiation. Historically, morphological data and the fossil record have been utilized to infer the evolution and relatedness of taxa within this class of organisms that are incongruent with emerging sequence based analysis. However, these sequence based phylogenies have been based on limited sequence and taxon sampling, and the relationships between major clades of cephalopods remain unclear. Here we resolve these relationships using targeted sampling of ultra-conserved elements (UCE) from taxa that span all cephalopod orders. Using 44 cephalopod taxa, we analyzed 455 UCE loci under maximum likelihood using IQtree yielding the first well-supported phylogeny of all Cephalopoda. The resulting phylogeny provides critically needed resolution for the earliest divergences in the Cephalopod tree of life, and a necessary framework for understanding the evolution of this emblematic clade of invertebrates.

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