Fitness consequences of marine larval dispersal: the role of neighbourhood density, arrangement, and genetic relatedness on survival, growth, reproduction, and paternity in a sessile invertebrate.

The article investigates how neighborhood density, spatial arrangement, and genetic relatedness influence survival, growth, reproduction, and paternity in the sessile marine bryozoan Bugula neritina, focusing on the fitness consequences of marine larval dispersal. Through three manipulative field experiments, the study found that increased density reduced colony survival but did not affect growth rate, while relatedness of neighbors had no significant impact on survival, growth, or reproductive output. Additionally, distance to the nearest neighbor did not influence the number of settlers produced, paternity share, or multiple paternity, with genetic analyses revealing unexpectedly large sperm dispersal distances and high multiple paternity mostly from outside the experimental arrays. These findings suggest limited disadvantages to the species’ typically short larval dispersal distances, as sperm dispersal and mating dynamics mitigate potential costs of reduced dispersal and kin competition.