Unveiling the Ancient Secrets of Lichens: A Revolutionary Discovery
Imagine a world 410 million years ago, a time when the Earth's ecosystems were still taking shape. A recent groundbreaking study, led by researchers supported by FAPESP, has shed light on the very first lichens to inhabit our planet, known as Spongiophyton. These ancient organisms, a fascinating blend of fungi and algae, have left an indelible mark on the fossil record, sparking debates about their true nature.
Published in the esteemed journal Science Advances, the study brings together researchers from 19 institutions, including the University of São Paulo (USP) and the Brazilian Center for Research in Energy and Materials (CNPEM). The lead author, Bruno Becker-Kerber, shares his remarkable journey of discovery, which began during his postdoctoral research at USP's Institute of Geosciences (IGc) and CNPEM, made possible by a FAPESP scholarship.
But here's where it gets controversial... Spongiophyton has long been a subject of speculation, with experts questioning whether it was a fungus, a plant, or a lichen. Thanks to the advanced light beams from Sirius, CNPEM's state-of-the-art synchrotron light source, combined with other cutting-edge techniques, the researchers were able to visualize structures that provided a definitive answer.
"With a high level of certainty, we can now state that Spongiophyton is the earliest known lichen on Earth," Becker-Kerber asserts. The study utilized various light sources to capture images at micrometric and nanometric scales, even producing three-dimensional images. Achieving a resolution of 170 nanometers, the researchers visualized potential reproductive structures, networks of hyphae (the filaments of multicellular fungi), and algae cells—strong indicators of a lichen.
The analyses also detected calcium, nitrogen compounds, and lipids, ruling out the possibility that Spongiophyton was a plant. Jochen Brocks, a co-author and professor at the Australian National University, emphasizes the significance of these findings in a press release: "The most resilient material in non-vascular plants is cellulose. In contrast, lichens are composed of chitin, the same material found in insect shells, which is rich in nitrogen. When we analyzed Spongiophyton, we detected an exceptionally strong nitrogen signal, a rare and robust piece of evidence."
Additionally, the study identified calcium microparticles in the ancient fossils, compatible with minerals produced by modern lichens as a form of sun protection—an unprecedented discovery.
Nathaly Archilha, another co-author and researcher at the Brazilian Synchrotron Light Laboratory (LNLS) of CNPEM, highlights the importance of combining traditional methods with innovative techniques: "The measurements guided us to key regions of the fossils, allowing us to obtain nanometric-scale images that revealed the intricate networks of fungi and algae, defining Spongiophyton as a true lichen."
The discovery of Spongiophyton is a father-son affair. Becker-Kerber found the fossil in 2021 at a quarry in Rio Verde de Mato Grosso, Mato Grosso do Sul, his home state. Accompanied by his father, Gilmar Kerber, an enthusiastic paleontologist and now a doctoral student in animal biology at the Federal University of Mato Grosso do Sul (UFMS), Becker-Kerber explains the significance of their find: "Each fossil is a window into the past, and this one offers a new perspective on how life conquered the terrestrial environment."
Quarries, Becker-Kerber notes, are treasure troves for paleontologists. "My father hammered a rock, and when it split open, I realized it contained something unprecedented for that region." He immediately wrapped the material in sterile aluminum foil to minimize contamination, enabling sensitive analyses, including the identification of molecular biomarkers.
The study suggests that the first lichens emerged in the cold regions of the ancient supercontinent Gondwana, which now corresponds to South America and Africa. Contrary to previous beliefs that lichens were marginal organisms living in specific conditions, the results indicate that they were pioneers in transforming the planet's surface and played a pivotal role in the transition of life from water to land.
"Even today, we observe how lichens alter rocky substrates, dissolving rocks, and producing biomass used by plants and animals. This role was likely even more significant during that period, enabling the emergence of the complex ecosystems we have today, such as forests and fields," Becker-Kerber concludes.
The São Paulo Research Foundation (FAPESP) has been instrumental in supporting scientific research across all fields of knowledge, awarding scholarships, fellowships, and grants to researchers affiliated with higher education and research institutions in the State of São Paulo, Brazil. FAPESP recognizes the importance of international collaboration and has established partnerships with funding agencies, higher education institutions, private companies, and research organizations worldwide, known for their research excellence. FAPESP encourages its grant recipients to further develop their international collaborations, fostering a global network of scientific excellence.
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