Lichen-forming fungi in postindustrial habitats involve alternative photobionts.

Mycobionts of many lichen genera appear to demonstrate strong selectivity in the choice of algal partner. The biological properties of a photobiont and its availability in an environment significantly determine the habitat requirements of lichens. Flexibility in photobiont choice extends the ecological amplitude of lichens; therefore, it may constitute an important adaptive strategy for colonization of extreme habitats. The photobiont inventory of the three epigeic lichens most resistant to soil pollution, i.e., , and the hyperaccumulator , was examined to verify whether and to what extent algal composition depends on the type of habitat and substrate enrichment with heavy metals. Photobionts and were identified in the studied lichen species; however, the presence of was directly related to anthropogenic sites with technogenic substrates, and the proportion of lichen specimens with these algae clearly depended on the level of heavy-metal soil pollution and the habitat type. The total number of algal haplotypes increased with increasing soil pollution, and the richness was associated more with soil pollution than with a given lichen species. Additionally, a large number of lichen individuals bearing multiple algal genotypes at polluted sites were recorded. Although lichens were previously thought to be restricted to , they are able to start the relichenization process with under specific habitat conditions and to establish a stable association with these algae when colonization of disturbed sites takes place. Comparative analysis of the internal transcribed spacer (ITS) rDNA sequences revealed as many as 13 haplotypes of , and phylogenetic analysis grouped them into two different clades. Such a high level of genetic diversity indicates that is well adapted to metal pollution and could be an alternative photosynthetic partner for certain lichens, especially in polluted sites.