Identification of asteroid genera with species capable of larval cloning.

Asexual reproduction in larvae, larval cloning, is a recently recognized component of the complex life histories of asteroids. We compare DNA sequences of mitochondrial tRNA genes (Ala, Leu, Asn, Pro, and Gln) from larvae in the process of cloning collected in the field with sequences from adults of known species in order to identify asteroid taxa capable of cloning. Neighbor-joining analysis identified four distinct groups of larvae, each having no, or very little, sequence divergence (p distances ranging from 0.00000 to 0.02589); thus, we conclude that each larval group most likely represents a single species. These field-collected larvae cannot be identified to species with certainty, but the close assemblage of known taxa with the four larval groups indicates generic or familial identity. We can assign two of the larval groups discerned here to the genera Luidia and Oreaster and another two to the family Ophidiasteridae. This study is the first to identify field-collected cloning asteroid larvae, and provides evidence that larval cloning is phylogenetically widespread within the Asteroidea. Additionally, we note that cloning occurs regularly and in multiple ways within species that are capable of cloning, emphasizing the need for further investigation of the role of larval cloning in the ecology and evolution of asteroids.