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As thick as three in a bed
1Biodiversity and Conservation Biology, Swiss Federal Institute for Forest, Snow and Landscape Research, WSL, Zürcherstr. 111, Birmensdorf, CH-8903, Switzerland.
Molecular Ecology
|July 15, 2016
Summary
Lichens can grow larger by forming tripartite associations with nitrogen-fixing cyanobacteria. This symbiotic shift allows them to thrive in nutrient-poor environments, demonstrating a key evolutionary adaptation in lichen biology.
Area of Science:
- Lichenology
- Symbiotic Interactions
- Evolutionary Biology
Background:
- Lichen symbiosis involves a fungus and a photobiont (alga or cyanobacterium).
- Transitions to cyanobacterial photobionts, including tripartite associations, are rare but significant.
- Tripartite lichens are highly productive and contribute to nitrogen cycling in ecosystems.
Discussion:
- This study investigates photobiont shifts in the Trapelia-Placopsis clade (Agyriales).
- Morphometric data and a fungal phylogeny were used to analyze transitions from green algal to tripartite associations.
- Phylogenetic comparative methods explored the role of cyanobacteria in lichen size evolution.
Key Insights:
- Cyanobacterial symbiosis, particularly tripartite associations, correlates with increased lichen size.
- The volume of cephalodia (cyanobacteria-containing structures) is linked to thallus thickness.
- A ninefold increase in fruiting body core volume was observed in tripartite species.
Outlook:
- Cyanobacterial symbiosis may enable lichens to overcome size limitations in oligotrophic habitats.
- This research highlights the interplay between ecology, phylogeny, and lichen development.
- The Trapelia-Placopsis clade serves as a model for understanding lichen evolution and adaptation.