EVOLUTIONARY HISTORY OF DECAPODIFORM CEPHALOPODS: THE IMPACT OF "OMICS" DATA ON PHYLOGENY (Invited Presentation)

The molluscan class Decapodiformes (Mollusca: Cephalopoda) comprises diverse and enigmatic group of species of squid, bobtail squid, cuttlefishes and their relatives. Known to inhabit marine ecosystems from shallow coastal waters to low oxygen mesopelagic waters to polar waters, decapodiforms possess a breadth of adaptations unique among metazoans. Phylogenetic relationships among the squids and cuttlefishes have resisted clarification for decades, despite multiple analyses of morphological, molecular, and combined data sets. More recently, analyses of complete mitochondrial genomes and hundreds of nuclear loci have yielded similarly ambiguous results. Of particular interest is the position of the for the lone species in the order Spirulida, Spirula spirula. Also known as the Ram's Horn Squid, Spirula spirula is the only living cephalopod with a chambered, spiral-shaped, internal calcareous phragmocone (shell), more reminiscent of ancestral cephalopods. While long recognized as a member of Decapodiformes, the relationship between Spirulida and the remaining decapodiforms—Oegopsida (oceanic squid), Myopsida (inshore squid), Sepiolida (bobtail squid), Idiosepiida (pygmy squid), Bathyteuthoidea (comb-finned squid) and Sepiida (cuttlefish)—remains unclear. Early morphological studies grouped Spirulida with Sepiida due to the shared presence of a calcified internal shell, but this relationship was questioned in subsequent work due to the unusual combination of characters seen in Spirulida (e.g., Spirula has an open, oegopsid-like eye). Here, will synthesize current understanding of decapodiform relationships and present a new study in which we incorporate new, high-quality transcriptome data for several new decapodiform taxa, including a specimen of Spirula spirula collected in the Gulf of Mexico with previously published transcriptome data to help resolve the impact confounding factors such as taxon sampling, orthology inference, contamination, conflicting signals, variable rate heterogeneity, have on our ability to infer higher level phylogenetic relationships among Decapodiformes.