Lichens Rise to Promi­nence

Note­wor­thy

Lichens, a sym­bio­sis be­tween a fun­gus and a pho­to­syn­thetic part­ner – ei­ther an alga or a cyanobac­terium, are ap­par­ently sim­ple or­gan­isms that nonethe­less hide great com­plex­ity. Con­se­quently, un­der­stand­ing as­pects of their bi­ol­ogy and func­tion­al­ity, their tax­o­nomic clas­si­fi­ca­tion, and the re­cruit­ment of con­stituent mem­bers, in­clud­ing ad­di­tional mi­cro­bial part­ners, re­mains a chal­lenge.

Artis­tic re­con­struc­tion of Spon­gio­phy­ton dur­ing the Early De­von­ian in the high lat­i­tude de­po­si­tional sys­tem of the Paraná Basin. Source

A re­cent study sug­gests a new role for lichens: they may have in­flu­enced the col­o­niza­tion of land, one of the most im­por­tant mile­stones of life on our planet. In this work, re­searchers solved a long-stand­ing de­bate re­gard­ing a wide­spread fos­sils from the De­von­ian pe­riod called Spon­gio­phy­ton. By in­ves­ti­gat­ing the mor­phol­ogy, chem­istry, and min­er­al­ogy of Spon­gio­phy­ton from rocks in Brazil, they show that these fos­sils came from lichens, rather than from al­gae.

These fos­sils es­tab­lish that lichens ex­isted about 410 mil­lion years ago, af­ter vas­cu­lar plants emerged but be­fore these flour­ished on land. This find­ing there­fore in­di­cates that lichens could have acted as pi­o­neer or­gan­isms that al­tered soil con­di­tions and en­abled col­o­niza­tion of ter­res­trial ecosys­tems and the en­su­ing ex­pan­sion of plants and an­i­mals.