Meeting Abstract

12.4  Tuesday, Jan. 4  Larval settlement preference maximizes genetic mixing in the marine bryozoan Bugula stolonifera JOHNSON, C H; Harvard University cjohnson@oeb.harvard.edu

Conspecific aggregations in terrestrial and aquatic organisms can have a significant effect on an individual’s survival, growth, and reproductive fitness, particularly if these aggregations are composed of closely related individuals. For many species of bryozoans, larvae routinely metamorphose on conspecific colonies. In this study we conducted genetic analyses of attached individuals to examine potential kin aggregations in the marine bryozoan Bugula stolonifera. Colonies were collected from Eel Pond, Woods Hole, Massachusetts. These colonies and their attached individuals were genotyped and compared to assess genetic relatedness within and among these groups relative to the overall genetic variability of the sampling site. Overall, the population of B. stolonifera at this site was found to be outside of Hardy-Weinberg equilibrium due to significant levels of inbreeding. No significant genetic differentiation was found between any groups, documenting that a group containing a colony and its attached individuals had as much genetic variability as was found for the entire sampling site. Parentage-exclusion analyses showed that the vast majority of attached individuals (>93%) could not have derived from the colony on which they were attached. Kinship analyses showed that the majority of attached individuals (≈63%) shared less than a half-sibling relationship. These results suggest that a colony’s nearest neighbors are not composed of siblings, and thus larval settlement preference can maximize outcrossing in this inbreeding population.