Photobiont Diversity in Indian Cladonia Lichens, with Special Emphasis on the Geographical Patterns

Abstract

The biogeography of lichen photobionts is still poorly known, in particular, as the majority of reports have been published from Europe and North America. In this study, we examined the diversity of Asterochloris photobionts from terricolous lichens (Cladonia spp.) collected in five different areas in India and Nepal during the years 2007 and 2010. In total, we obtained 20 internal transcribed spacer (ITS) ribosomal DNA (rDNA) photobiont sequences from 11 different Cladonia species. The phylogenetic position of Asterochloris photobionts was investigated by the phylogenetic analysis based on the concatenated ITS rDNA and actin type I intron dataset. The newly obtained photobiont sequences were inferred in six clades, including two novel clades exclusively formed by photobionts of Indian Cladonia lichens. As the sequences of these two clades were genetically considerably different from all other known Asterochloris lineages, they most probably represent new, undescribed photobiont species. According to our data, three clades seem to have rather restricted distribution, reported so far only from Europe and Asia, respectively. However, we propose that the restricted distribution of these three photobiont clades is not caused by either historic or biological factors, but more likely by specific climatic or habitat preferences and the under-exploration of such habitats in different regions.