Paedomorphosis and evolution of sequestrate Basidiomycetes

Abstract

Current theories on the evolution of sequestrate (enclosed) basidiomes explain the origin of these forms in a gradualist adaptational process led by selective forces, such as drought and animal consumption. Paedomorphosis (the retention of juvenile traits) has been invoked as the phenomenon underlying sequestration, but many consequences of this process have not yet been explored. Our present interpretation of sequestrate morphologies, in light of Stephen Jay Gould’s characterization of neoteny (retention of juvenile features in an adult stage with mature reproductive structures) and progenesis (the onset of sexual maturity in a morphologically immature stage that does not reach the mature morphology observed in the ancestral form), both involved in paedomorphosis, implies that the origin of sequestrate basidiomes might constitute two distinct evolutionary processes. These two processes could be recognized among fungi by contrasting their morphological plasticity, phylogenetic diversification, and ecological patterns. The hypotheses discussed here provide new insights for interpreting and studying the evolution of sequestrate fungi.