Evidence for a genetic sex determination in Cnidaria, the Mediterranean red coral (Corallium rubrum)

• Main Authors: M. Pratlong, A. Haguenauer, S. Chenesseau, K. Brener, G. Mitta, E. Toulza, M. Bonabaud, S. Rialle, D. Aurelle, P. Pontarotti
• Format: Article
• Language: English
• Published: The Royal Society 2017-01-01
• Series: Royal Society Open Science
• Subjects: genetic sex determination; corallium rubrum; rad-sequencing; cnidaria
• Online Access: https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.160880

Sexual reproduction is widespread among eukaryotes, and the sex-determining processes vary greatly among species. While genetic sex determination (GSD) has been intensively described in bilaterian species, no example has yet been recorded among non-bilaterians. However, the quasi-ubiquitous repartition of GSD among multicellular species suggests that similar evolutionary forces can promote this system, and that these forces could occur also in non-bilaterians. Studying sex determination across the range of Metazoan diversity is indeed important to understand better the evolution of this mechanism and its lability. We tested the existence of sex-linked genes in the gonochoric red coral (Corallium rubrum, Cnidaria) using restriction site-associated DNA sequencing. We analysed 27 461 single nucleotide polymorphisms (SNPs) in 354 individuals from 12 populations including 53 that were morphologically sexed. We found a strong association between the allele frequencies of 472 SNPs and the sex of individuals, suggesting an XX/XY sex-determination system. This result was confirmed by the identification of 435 male-specific loci. An independent test confirmed that the amplification of these loci enabled us to identify males with absolute certainty. This is the first demonstration of a GSD system among non-bilaterian species and a new example of its convergence in multicellular eukaryotes.