Curator and Vice President of Science and Education at the Field Museum of Natural History in Chicago (IL, USA). Formerly, president of the International Association for Lichenology (IAL). His research employs a broad scope of evolutionary biology to address issues of spatial and temporal patterns of diversification, understanding delimitation of species, reproductive modes and hybridization of fungi, and biodiversity of tropical fungi, with a focus on lichenized fungi and their photosynthetic partners.
