Mother-of-pearl (left) rock mother-of-pearl (centre) & a hybrid specimen (right). | R.L./IEO


The mother-of pearl Pinna nobilis has been dying off in the Mediterranean for years, because of a parasite called Haplosporiudium pinnae and has been listed as an endangered species in the Spanish Catalogue of Threatened Species and IUCN Red List.

Now Researchers from the Balearic Oceanographic Centre of the Spanish Institute of Oceanography o5 IEO and the Center de Recherches Insulaires et Observatoire de l’Environnement, or Criobe, have found evidence of hybridisation between the Pinna nobilis mother-of-pearl and rock mother of pearl.

Several studies have been carried out to protect the mother-of-pearl nobilis and IEO Researchers from the National Maritime Terrestrial Park in the Cabrera have been monitoring surviving specimens.

Morphological and genetic analysis of these specimens has identified the hybridisation of Pinna nobilis mother-of-pearl and rock mother-of-pearl for the first time and that could help researchers understand the immunity of some individuals to the pathogen, because rock mother-of-pearl is resistant to the parasite and hybrids could be as well.

"All surviving specimens that were previously thought to be Pinna nobilis will have to pass a genetic identity test, because some of them may be hybrid specimens," said IEO Researcher and article author, Maite Vázquez-Luis.

Results published in the journal, Molecular Biology Reports state that three of the individuals studied had intermixed morphological characteristics of the shell and mantle, exhibiting features of both species and molecular analysis supports this finding.

Hybridisation is a common process in nature; it’s considered very important in the evolution of species and can lead to its collapse or the formation of a new one.

"It is not yet known whether these hybrids are fertile or not, more studies are needed to help determine whether the surviving individuals found in Spain and other countries are truly Pinna nobilis or hybrid specimens,” said Vázquez-Luis.