The biggest and oldest clones in the world
While many organisms reproduce sexually, there are others that reproduce by cloning themselves. This occurs more often in plants than in animals, with the spider plant one species where asexual plantlets develop from a parent.
Being a clone can be problematic to an organism, as disease which affects one individual will likely affect them all.
For instance, the Gros Michel was the world’s most consumed banana for over a century and was widely grown through asexual reproduction. However, the fungal Panama disease decimated plantations during the 1950s, which caused producers to switch to the Cavendish banana instead.
Despite this, clonal organisms are among some of the largest in the world. Pando is the name given to a group of around 40,000 aspen trees in Utah, USA, which are all clones of a single organism and share the same root system.
Meanwhile, meadows of clonal Posidonia oceanica found around the island of Formentera in the Mediterranean Sea are at least 12,500 years old but may be tens of thousands of years older.
The secret of P. australis‘s success in Shark Bay may lie in its genetics. Researchers found that the seagrass is a polyploid organism, with double the normal number of chromosomes.
‘Diploid organisms, like you and me, only inherit half of their parents’ genome, whereas this seagrass has all of it,’ Elizabeth explains. ‘We suspect that this gives the plant an advantage over a diploid organism as it has all of the genes that help it survive in its current environment, as well as more genes which could help it survive in others.
‘Reproducing clonally ensures the seagrass keeps the same genetics, as sexual reproduction in a diploid organism leads to new combinations of genes. While some will lead to new adaptations and an advantage, others will put it at a disadvantage.’
The genetic makeup of the seagrass is well suited to Shark Bay, which is buffered from ocean swells that could break the plant apart, and help it tolerate a wide range of temperatures and salinities. But climate change could pose a threat to the future of this enormous organism.