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A relic of early life on Earth- The Lichen!

Imagine a pristine but barren earth 600 million years ago! If life began in the Oceans 3.5 billion years ago, what life forms actually colonised the land mass itself all that time ago: maybe the early colonisers of land were Photosynthetic bacteria like cyanobacteria and their cousins that could use reduced Sulphur as the electron donor? But what about early multi-cellular organisms?

As a species Lichens are considered to be one of the early colonisers of land, some 600 million years ago. Some of the independent fungal species that later arose, had their origins from these Lichens. It is possible to find Lichens in some of the most inhospitable climates on Earth, from the dry expanses of  the Sahara desert to the frozen valleys of Antarctica.

The Tree Lichen, Evernia prunastri, chosen for the 25 genomes project, can be found in many parts of the World including the United Kingdom. but particularly good specimens are confined to woodlands and Moors. They prefer to grow on bark of deciduous trees but have been found on Evergreens on occasion. The possibility of sequencing the Tree Lichen will help to develop  further insights into their unique Symbiotic biology.

Above-Evernia prunastri, the Tree Lichen. Photo taken in Dartmoor

Lichens of bark come in other forms too as shown below (Photo taken in Sawston):-

As a comparison, many Lichens will grow on rocks of various types. Some examples are shown below. The first Lichen that resembles a Radio Telescope in shape, was taken on a tombstone in Sawston, near Cambridge UK, while the last one was from a rock in the glorious forested gorge of the Ardeche in the south of France.

 The diversity of Lichens is testament to their robustness, all the way from  Antarctica, through the tropics of Africa, the temperate zones of Europe and onto the tundra and Artic circle. Sequencing of the Tree Lichen is a unique opportunity to understand these exquisite life forms.