*2.4. Reproductive Strategies in Lichens*

Lichens are able to reproduce both sexually and asexually. Sexual reproduction is carried out through sexual spores of the mycobiont reproducing the fungus alone. Vegetative reproduction is carried out through various types of propagules (e.g., conidia, thallus fragments, schizidia, lobules, isidia, soredia). Among them, (1) soredia are more or less granular aggregations of hyphal and algal cells ranging from 20 to 100 μm in diameter or more, and (2) isidia are small thallus outgrowths with varied morphology (e.g.,

cylindrical, clavate, coralloid) containing both symbionts [6,7]. In this work, we define "sexual species" as those species that reproduce mainly sexually through ascospores and "vegetative species" as those that reproduce mainly through vegetative diaspores. Among these latter, we only considered the most representative ones, namely soredia and isidia, while we did not take into account other less frequent types of propagules, such as conidia, thallus fragments, schizidia, and lobules.
