title: Phylogenetic analysis of higher-level relationships within Hydroidolina (Cnidaria: Hydrozoa) using mitochondrial genome data and insight into their mitochondrial transcription.
abstract: Hydrozoans display the most morphological diversity within the phylum Cnidaria. While recent molecular studies have provided some insights into their evolutionary history, sister group relationships remain mostly unresolved, particularly at mid-taxonomic levels. Specifically, within Hydroidolina, the most speciose hydrozoan subclass, the relationships and sometimes integrity of orders are highly unsettled. Here we obtained the near complete mitochondrial sequence of twenty-six hydroidolinan hydrozoan species from a range of sources (DNA and RNA-seq data, long-range PCR). Our analyses confirm previous inference of the evolution of mtDNA in Hydrozoa while introducing a novel genome organization. Using RNA-seq data, we propose a mechanism for the expression of mitochondrial mRNA in Hydroidolina that can be extrapolated to the other medusozoan taxa. Phylogenetic analyses using the full set of mitochondrial gene sequences provide some insights into the order-level relationships within Hydroidolina, including siphonophores as the first diverging clade, a well-supported clade comprised of Leptothecata-Filifera III-IV, and a second clade comprised of Aplanulata-Capitata s.s.-Filifera I-II. Finally, we describe our relatively inexpensive and accessible multiplexing strategy to sequence long-range PCR amplicons that can be adapted to most high-throughput sequencing platforms.
authors.affiliation: Department of Invertebrate Zoology, Smithsonian Institution , Washington, DC , USA.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Kayal
authors.affiliation: Department of Invertebrate Zoology, Smithsonian Institution , Washington, DC , USA.
authors.forename: Bastian
authors.initials: B
authors.lastname: Bentlage
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Kansas , Lawrence, KS , USA.
authors.forename: Paulyn
authors.initials: P
authors.lastname: Cartwright
authors.affiliation: Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa , Honolulu, HI , USA.
authors.forename: Angel A
authors.initials: AA
authors.lastname: Yanagihara
authors.affiliation: Japan Agency for Marine-Earth Science and Technology (JAMSTEC) , Yokosuka , Japan.
authors.forename: Dhugal J
authors.initials: DJ
authors.lastname: Lindsay
authors.affiliation: Institute of Marine Science, University of Alaska Fairbanks , Fairbanks, AK , USA.
authors.forename: Russell R
authors.initials: RR
authors.lastname: Hopcroft
authors.affiliation: Department of Invertebrate Zoology, Smithsonian Institution , Washington, DC , USA ; National Systematics Laboratory of NOAA's Fisheries Service, National Museum of Natural History , Washington, DC , USA.
authors.forename: Allen G
authors.initials: AG
authors.lastname: Collins
keywords: Aplanulata; Capitata; Filifera; Leptothecata; Low-cost multiplexing library preparation; Mitochondrial gene expression; Phylomitogenomics; Siphonophora