Molecular and Physical Relationships among Individuals in a Phoronis vancouverensis Clump

Abstract

Within the bilateria, in the group Lophotrochozoa, there are at least two phyla that have evolved coloniality: Bryozoa and Entoprocta. Most of the phyla are solitary, and reproduce only sexually (Davidson et al. 2004). However, several other phyla, such as annelids and flatworms, have the ability to reproduce asexually (Yoshida et al. 2010) (Kobayashi et al. 2009). Phylogenetic analysis of Phoronida and Brachiopoda showed it to form a monophyletic clade (Cohen et al. 1998), but some species of phoronids such as Phoronis vancouverensis form a clump. People have long questioned if this clump is colonial, yet I have been unable to find scientific reports that indicate how individuals of P. vancouverensis are related to one another within a clump. There are three possibilities, or combinations thereof, for the relationship among the clump of P. vancouverensis. The first possibility is that individuals of P. vancouverensis within a clump are solitary and reproduce only sexually. The second possibility is that P. vancouverensis has the ability to produce asexually by budding or fission, but individuals do not maintain connections in a clump. The third possibility is that P. vancouverensis is truly colonial, thus physically connected to one another and exhibits asexual reproduction in addition to sexual reproduction.