Data from: The evolution of fungal substrate specificity in a widespread group of crustose lichens

Lichens exhibit varying degrees of specialization with regard to the
surfaces they colonize, ranging from substrate generalists to strict
substrate specialists. Though long recognized, the causes and consequences
of substrate specialization are poorly known. Using a phylogeny of a
150-200 MYA clade of lichen fungi, we asked whether substrate niche is
phylogenetically conserved, which substrates are ancestral, whether
specialists arise from generalists or vice versa, and how specialization
affects speciation/extinction processes. We found strong phylogenetic
signal for niche conservatism. Specialists evolved into generalists and
back again, but transitions from generalism to specialism were more common
than the reverse. Our models suggest that for this group of fungi,
“escape” from specialization for soil, rock and bark occurred, but
specialization for wood foreclosed evolution away from that substrate
type. In parallel, speciation models showed positive diversification rates
for soil and rock dwellers but not other specialists. Patterns in the
studied group suggest that fungal substrate specificity is a key
determinant of evolutionary trajectory for the entire lichen symbiosis.