Implications of Extreme Life Span in Clonal Organisms: Millenary Clones in Meadows of the Threatened Seagrass Posidonia oceanica

Abstract

The maximum size and age that clonal organisms can reach remains poorly known, although we do know that the largest natural clones can extend over hundreds or thousands of metres and potentially live for centuries. We made a review of findings to date, which reveal that the maximum clone age and size estimates reported in the literature are typically limited by the scale of sampling, and may grossly underestimate the maximum age and size of clonal organisms. A case study presented here shows the occurrence of clones of slow-growing marine angiosperm Posidonia oceanica at spatial scales ranging from metres to hundreds of kilometres, using microsatellites on 1544 sampling units from a total of 40 locations across the Mediterranean Sea. This analysis revealed the presence, with a prevalence of 3.5 to 8.9%, of very large clones spreading over one to several (up to 15) kilometres at the different locations. Using estimates from field studies and models of the clonal growth of P. oceanica, we estimated these large clones to be hundreds to thousands of years old, suggesting the evolution of general purpose genotypes with large phenotypic plasticity in this species. These results, obtained combining genetics, demography and model-based calculations, question present knowledge and understanding of the spreading capacity and life span of plant clones. These findings call for further research on these life history traits associated with clonality, considering their possible ecological and evolutionary implications.

Long telomeres are associated with clonality in wild populations of the fissiparous starfish Coscinasterias tenuispina

“…In these cases, genetic analyses can reveal the level of clonality within a population as well as the extent of a clone, thus providing information regarding its age and longevity (Ally et al, 2010). Indeed, extremely large and longlived clonally propagating populations exist, such as some sea grass species, with clones that are estimated to be 1000 year (Reusch et al, 1999) or more (Arnaud-Haond et al, 2012). In the case of a terrestrial tree, the age of some clones have been estimated as old as 10 000 year (Ally et al, 2010) and in cold waters, clonal individuals of the coral Lophelia pertusa are estimated to be 4500-6000 year (Dahl et al, 2012).…”

Functional, Phylogenetic and Host-Geographic Signatures of Labyrinthula spp. Provide for Putative Species Delimitation and a Global-Scale View of Seagrass Wasting Disease

“…However, they also represent our best cases of host specificity: sampling spanned several years as well as several sites, but no shared haplotypes were found among these hosts (in this study). Both of these hosts are also extremely long-lived clonal species (centuries to millennia; Arnaud-Haond et al 2012) that share a bioregion, suggesting a relatively recent divergence among these haplotypes/putative species. For the only previously described and sequenced marine species, L. zosterae, we also provide basic morphological data (see Results for our isolate 95w1 (haplotype 1, species A)) showing considerable overlap with the diagnosis of L. zosterae by Muehlstein et al (1991).…”

Response of key stress-related genes of the seagrass <i>Posidonia oceanica</i> in the vicinity of submarine volcanic vents

“…The volcanic vent in Ischia could in fact be as old as about 2000 years, as indicated by archaeological evidence (Lombardi et al, 2011), whereas the vent in Panarea is only about 10 years old. It is quite possible that some of the Ischia genotypes of P. oceanica have been there since the onset of the volcanic vents as it has been recently revealed that the longevity of this species can be up to thousands of years (Arnaud-Haond et al, 2012). This is the first time that a gene expression study has been performed in marine plants in the vicinity of submarine volcanic vents, which are generally assumed to be good natural laboratories for investigating the effects of increased CO 2 and ocean acidification on marine organisms.…”