Convergent evolution in discomycetes from bark and wood

Abstract

Dry weathered wood (lignum and arid bark support a discomycete flora which is taxonomically extremely diverse and contains a high percentage of species with characters not found in Discomycetes of more mesic habitats. A large proportion of filiform-spored, and all muriform-spored non-lichenized Discomycetes occur in this habitat. Most lignicolous Discomycetes have either a pigmented epithecium or a dark margin which covers the hymenium when dry and many have reviving, gelaious ascomata. Their asci often have a simplified structure difficult to interpret. Weathered wood is a niche which has long continuity in geologic time but is relatively unfavorable for fungi because of exposure, aridity and low nutrient levels. Strong selective pressure has consequently been exerted on those fungi able to colonize it, resulting in a high incidence of convergent evolution.