Lichen myco- and photobiont diversity and their relationships at the edge of life (McMurdo Dry Valleys, Antarctica)

Abstract

Lichen-forming fungi are among the most diverse group of organisms in Antarctica. Being poikilohydric, lichens are able to cope with harsh environmental conditions that exclude other organisms like vascular plants. The McMurdo Dry Valleys (Victoria Land, Continental Antarctica) are a hyperarid cold desert where macroscopic life is reduced to a few lichens and bryophyte species. We investigated the diversity of lichen-forming fungi and their associated photobionts in three valleys (Garwood, Marshall, and Miers). Correct identification of lichen-forming fungi from extreme ecosystems is complicated by the presence of numerous sterile and extremely modified thalli. To overcome this problem, we used a combined approach for the identification of the species present in the area, the first involving identification by means of standard characters and the second, two DNA-based (ITS region) species delimitation methods (General Mixed Yule-Coalescent model and genetic distances). In addition, we also used ITS sequences for the identification of the photobionts associated with the mycobionts. We studied the relationships between both bionts and assessed the degree of selectivity and specificity found in those associations. We also looked for landscape level spatial patterns in these associations. The two DNA-based methods performed quite differently, but 27 species of lichen-forming fungi and five putative species of photobionts were found in the studied area. Although there was a general trend for low selectivity in the relationships, high specificity was found in some associations and differential selectivity was observed in some lichen-forming fungi. No spatial structure was detected in the distribution of photobionts in the studied area.

A worldwide phylogeography of the whiteworm lichens Thamnolia reveals three lineages with distinct habitats and evolutionary histories

“…Lichens are formed as a symbiosis between two main partners, a mycobiont and a photobiont. Recent lichen studies strive to integrate both morphological and molecular information from the symbiotic partners (e.g., Chen, Werth, & Sork, ; Fernandez‐Mendoza et al., ; Perez‐Ortega, Ortiz‐Alvarez, Allan Green, & de Los Rios, ; Spribille et al., ; Werth & Sork, ). In this study, we focused our efforts to describe and understand the mycobiont population structure and the associated photobionts in Thamnolia .…”

Fungal specificity and selectivity for algae play a major role in determining lichen partnerships across diverse ecogeographic regions in the lichen‐forming family Parmeliaceae (Ascomycota)

“…), Protoparmeliopsis muralis (Guzow‐Krzemińska ) and Rhizoplaca macleanii (Pérez‐Ortega et al . ). Species‐level identifications of the sampled lichenized fungal hosts were based on phenotype‐based descriptions and previous molecular phylogenetic analyses (Crespo et al .…”

Biological Soil Crusts

“…Although the identification of lichens is difficult because of the presence of numerous sterile and extremely modified thalli from maritime climate-influenced Valleys, like the Garwood or Miers Valley (Fig. 8.1), up to 15 lichen species could be identified (Pérez-Ortega et al 2012). However, their contribution/relation to BSC remained unclear.…”