Meeting Abstract
Although the vast majority of the hydrozoan clade Aplanulata comprises species that display a solitary benthic stage, some members of the genus Ectopleura appear to have re-evolved coloniality superficially similar to other hydrozoans outside Aplanulata. However, these colonies are not formed in the manner typical of other hydrozoans via asexual budding in the adult colony. Rather, the colonies of Ectopleura larynx are the products of fusion of sexually reproduced offspring onto parent colonies. As a result, individual colonies form from chimeric mixtures from genotypes, setting up a potential evolutionary conflict. If chimeric lineages vary in their ability to access the germline, germline parasitism may arise where one lineage gets most of the reproductive output while not contributing equally to the somatic functioning of the colony. In order to assess the extent to which the potential for germline parasitism is present in E. larynx given its novel mode of colony formation, we determined the level of genetic variation in an E. larynx colony relative to the accessible genetic variation in the local area and characterized genetic relationships present in colonies of E. larynx using a RAD-seq approach. Our results indicate that E. larynx colonies comprise a combination of polyps that vary in genetic relatedness from clones, to siblings, to non-siblings. However, the potential conflict inherent in this genetic chimerism is potentially mitigated by the extremely low overall genetic diversity found in populations of E. larynx, with minimal genetic distinction between self- and non-self in these populations.
