The Mycobiont Role in Crustose Lichen Expansion on Cobbles in the Negev Desert

摘要

Whereas the role of the photobiont within microlichen symbiosisis indisputable, the role of the mycobiont in the symbiosisis still questionable. Here we report a unique expansion of the endolithiclichen Caloplaca alociza on cobbles in the Negev Desert dueto structural change induced by the mycobiont burrowing activity.By increasing the water-holding capacity of the rock it facilitateslichen expansion from the cobble margins (where they establishdue to water capillary rise) to its sides. And thus, while rare at thecobble top, lichen expansion is taking place to the sides of the cobblealbeit the fact that dew (the main water source) is significantlylower at the cobble sides than at its top.