Evolutionary history of Southern Ocean Odontaster sea star species (Odontasteridae; Asteroidea)

Abstract

We investigated the recent evolutionary history of demersal sea stars in the genus Odontaster throughout the Western Antarctic waters and on the South American shelf. The mitochondrial 16S ribosomal and cytochrome c oxidase subunit I (COI) genes were sequenced from adult and larval specimens. TCS parsimony network analysis and Bayesian inference were used to examine evolutionary history. Hierarchical AMOVA and mitochondrial DNA diversity statistics were also computed. Additionally, morphological characters were used. In assessing O. validus, we discovered morphological and range descriptions of Odontaster species to be inaccurate and include other Odontaster species in the Southern Ocean. We found O. meridionalis on both sides of the Antarctic circumpolar current (ACC) and Antarctic polar front (APF), whereas O. validus and O. penicillatus do not appear to have permeated these oceanographic features. Additionally, we discovered previously unrecognized species of Odontaster. Subsequent examination revealed diagnostic morphological differences in the number of spinelets on the abactinal and actinal plates. Mitochondrial characterization of Odontaster species suggests their recent history has been influenced by the APF and ACC in different ways. With the exception of O. meridionalis, Odontaster species are restricted to either side of the Drake Passage. O. validus shows genetic connectivity throughout sampled Antarctic waters.