In the Mediterranean sea lives the most long-lived species of the biosphere

Researchers at CSIC have found in Formentera a clone of this marine plant which is 100,000 years old

A team of researchers from the Mediterranean Institute for Advanced Studies (IMEDEA, CSIC-UIB) has found on Formentera a clone of Posidonia oceanica, a threatened marine species which is endemic to the Mediterranean. The clone is 100,000 years old. The research results, which were published in the latest issue of the journal PLoS ONE, make this the longest-lived species of the biosphere.

The longevity key is clonal growth, a process that Posidonia shares with other sea grasses. This process is based on the constant division of the areas where new cells are generated, called meristems, and the extremely slow growth of their stems, called rhizomes.

The scientists have found that the rhizomes grow an inch every year and gradually spread until they occupy several kilometers while producing millions of plants from the same clone. The IMEDEA researcher Carlos Duarte, author of the study, explains that these rhizomes are very resistant to degradation and maintain connections with the same clone during thousands of years. The researcher adds that the process is slow because the stems are one centimeter in diameter, while leaves can reach one meter in length. In addition, its genome is extremely resistant to mutations.



Phenotypic plasticity

Researchers have taken samples around fifty seagrass meadows of the Mediterranean, from Cyprus to Almeria. After sequencing the plants they observed that many clones or genotypes were in meadows separated about 10 km from each other.

The results suggest that genotypes of this species can adapt to the environment adjusting their growth mode. In nutrient-poor regions, like the Mediterranean Sea, its growth is slower, roots will grow longer, and leaves will be longer and thinner, in order to improve efficiency, says Duarte.

The authors of the study have used a model to simulate the clonal growth and see if it is feasible to find the same clone despite the mutations. According to Duarte, the model verified that the samples were consistent with Posidonia’s clonal growth because it reproduced the same pattern of clonal dominance.

The work provides evidence that the age of clonal organisms, responsible for more than half of the biosphere primary production, “it has been systematically underestimated in the literature” and it also encourages further researche on life extension associated with clonality and its possible ecological and evolutionary implications.

Citation: Sophie Arnaud-Haond, Carlos M. Duarte, Elena Díaz-Almela, Núria Marbà, Tomás Sintes, Ester A. Serrão. Implication of extreme life span in clonal organisms: millenary clones in meadows of the threatened seagrass Posidonia oceanicaPLoS ONE. DOI: 0030454.


Pictures: Manu Sanfélix

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