Lichen speciation is sparked by a substrate requirement shift and reproduction mode differentiation

Abstract

We show that obligate lignicoles in lichenized Micarea are predominately asexual whereas most facultative lignicoles reproduce sexually. Our phylogenetic analyses (ITS, mtSSU, Mcm7) together with ancestral state reconstruction show that the shift in reproduction mode has evolved independently several times within the group and that facultative and obligate lignicoles are sister species. The analyses support the assumption that the ancestor of these species was a facultative lignicole. We hypothezise that a shift in substrate requirement from bark to wood leads to differentiation in reproduction mode and becomes a driver of speciation. This is the first example of lichenized fungi where reproduction mode is connected to substrate requirement. This is also the first example where such an association is demonstrated to spark lichen speciation. Our main hypothesis is that obligate species on dead wood need to colonize new suitable substrata relatively fast and asexual reproduction is more effective a strategy for successful colonization.

Regionally Varying Habitat Relationships in Lichens: The Concept and Evidence with an Emphasis on North-Temperate Ecosystems

“…It probably pays off not to be too selective when substrate diversity is very high and the colonization of emerging free surfaces by competitors is rapid. Similar thinking might also be used for relating lichens’ ability of long-distance dispersal to plasticity, but there are alternatives: either dispersal ability might be selected for because of a very specific and rare habitat (e.g., [ 263 ]), or it induces plasticity (i.e., the use of wider conditions which are more likely to be encountered at longer distances).…”

Isolation and Molecular Screening of Fungus as Agents in Cellulolytic Transformation Materials from Symbiotic Lichen

“…Lichen are organisms in a mutual symbiosis, consisting of a fungus functioning as a mycobiont, a photosynthetic bacterium that functions as the photobiont who could also be green algae or cyanobacteria (Kantelinen et al, 2022). Lignocellulose inducing fungi isolation from the lichen was done by separating the endophyte (endolichenic) mycobiont fungi from other organisms in the lichen by harvesting the mycelium and inoculating the mycelium in PDA (Potato Dextrose Agar) media.…”

“…Lichens are composite symbiotic organisms of algae or cyanobacteria (as the photobionts) living in mutualism with filament fungi species (as the mycobionts). Lichen can be found worldwide in various forest environments, tropical and subtropical, and are very important to the forest ecosystems (Kantelinen et al, 2022 andEsseen et al, 2022). Lichens are poikilohydric organisms that also serve as useful environmental global change indicators.…”