Seeing stars: a molecular and morphological investigation of the Odontasteridae (Asteroidea)
Janosik, Alexis Michele
Type of Degreedissertation
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Odontasterids (Asteroidea: Echinodermata) comprise a clade described by A.E. Verrill in 1899 and are placed within Valvatida, a derived assemblage of sea stars. Boasting a worldwide distribution, Odontasterids are found in the Southern, Atlantic, and Pacific Oceans, with a concentration in cold-water habitats, in high latitudes in the Southern Hemisphere. Most of species of Odontasteridae are from the lower shelf and upper bathyal region, though some have been collected in the tidal zone. Odontasteridae includes the following genera: Acodontaster, Diabocilla, Diplodontias, Eurygonias, Hoplaster, and Odontaster, which are typically characterized by two series of equal, opposite and usually conspicuous marginal plates without intermarginal channels. They also usually possess triangular mouths and two rows of tubefeet with suckers. This group of organisms occupies an important role in marine environments and is important to the understanding of marine systems. To date, the phylogenetic and evolutionary history within the Odontasteridae has not been rigorously examined. Here, a comprehensively sampled molecular and morphological phylogenetic analysis of the Odontasteridae to assess interrelationships among and between genera is presented. More specifically, the recent evolutionary history of the genus Odontaster throughout the Western Antarctic waters and on the South American shelf is examined. The mitochondrial 16S ribosomal and cytochrome c oxidase subunit I (COI) genes were sequenced from adult and larval specimens. Finally, at a finer scale, high resolution genetic markers (microsatellites) are used to look at the circumpolar population structure of Odontaster validus.