Biological interactions among extant and fossil clonal organisms

Biological interactions among clonal marine organisms are an important aspect of their behavior and are important in the construction of biological reefs. The interactions addressed here are among crustose and erect coralline algae, sponges, corals, and bryozoans, and may involve clones of the same species (conspecific), or different species (heterospecific). Conspecific interactions may be either between modules or clones that are produced asexually from one propagule, genetically identical, or between clones that are sexually produced from two or more propagules that may or may not be genetically identical. Juxtaposed genetically identical clones generally fuse whereas non-identical clones may or may not fuse, depending on their relatedness and histocompatibility. Most heterospecific clonal interactions are spatially competitive and result in overgrowths or stand-offs. Clone fission/fragmentation may occur as a result of biotic or abiotic processes that initially degrade but may eventually restore or even enhance ability to gain space and/or nutrients. Self-overgrowths also occur, usually over dead, diseased, or senescent parts of the same clone.