Date Published: November 4, 2009
Publisher: Public Library of Science
Author(s): Eneour Puill-Stephan, Bette L. Willis, Lynne van Herwerden, Madeleine J. H. van Oppen, Steve Vollmer. http://doi.org/10.1371/journal.pone.0007751
Abstract: Chimeras are organisms containing tissues or cells of two or more genetically distinct individuals, and are known to exist in at least nine phyla of protists, plants, and animals. Although widespread and common in marine invertebrates, the extent of chimerism in wild populations of reef corals is unknown.
Partial Text: Chimeras are organisms containing tissues or cells of two or more genetically distinct individuals  which typically arise through fusion. Fusion of genetically distinct individuals has been documented in at least nine phyla of protists, plants and animals , , including cnidarians in experimental allorecognition studies –. However, the extent to which natural chimeras occur in populations of reef corals is currently unknown.
High levels of chimerism (5% overall, or 3% according to a more conservative estimate based on the presence of at least two non-shared alleles) were found in two wild populations of the broadcast spawning coral, Acropora millepora, on the Great Barrier Reef. Both the Magnetic Island and the south-west Pelorus Island populations had similar levels of chimerism, i.e., 5% chimerism within each population based on genotypic differences at one allele, and 2% or 5%, respectively, based on genotypes displaying at least two non-shared alleles. These results indicate that chimerism is a common feature of this coral’s biology.