Fungal–algal association patterns in lichen symbiosis linked to macroclimate

Abstract

Both macroclimate and evolutionary events may influence symbiont association and diversity patterns. Here we assess how climatic factors and evolutionary events shape fungal-algal association patterns in the widely distributed lichen-forming fungal genus Protoparmelia. Multilocus phylogenies of fungal and algal partners were generated using 174 specimens. Coalescent-based species delimitation analysis suggested that 23 fungal hosts are associating with 20 algal species. Principal component analysis (PCA) was performed to infer how fungal-algal association patterns varied with climate. Fungi associated with one to three algal partners whereas algae accepted one to five fungal partners. Both fungi and algae were more specific, associating with fewer partners, in the warmer climates. Interaction with more than one partner was more frequent in cooler climates for both the partners. Cophylogenetic analyses suggest congruent fungal-algal phylogenies. Host switch was a more common event in warm climates, whereas failure of the photobiont to diverge with its fungal host was more frequent in cooler climates. We conclude that both environmental factors and evolutionary events drive fungal and algal evolution in Protoparmelia. The processes leading to phylogenetic congruence of fungi and algae are different in different macrohabitats in our study system. Hence, closely related species inhabiting diverse habitats may follow different evolutionary pathways.

Environment and host identity structure communities of green algal symbionts in lichens

“…Studies on symbiont diversity and community composition in lichens and other symbiotic associations have highlighted that fungal–algal community structure may not be predicted from niche properties and environment alone. Biotic factors, such as partner choice and population genetic processes of the host, may in fact play an important and, in some cases, even predominant role in determining the distribution of photobionts (Leavitt et al ., ; Magain et al ., ; Singh et al ., ). In accordance with this prediction, altitude was not the only driver of algal community assembly in our study.…”

The complexity of symbiotic interactions influences the ecological amplitude of the host: A case study in Stereocaulon (lichenized Ascomycota)

“…Previous ecological studies on lichen phycobionts focused mainly on the type of growth substrate (Bačkor et al., ; Leavitt et al., ; Muggia et al., ). Several studies have investigated the effects of various climatic conditions (Fernández‐Mendoza et al., ; Grande et al., ; Leavitt et al., ; Marini, Nascimbene, & Nimis, ; Peksa & Škaloud, ; G. Singh et al., ). As of late, Rolshausen, Dal Grande, Sadowska‐Deś, Otte, and Schmitt () described mutualist‐mediated climatic niche expansion.…”

“…Previous ecological studies on lichen phycobionts focused mainly on the type of growth substrate (Bačkor et al, 2010;Leavitt et al, 2013;Muggia et al, 2014). Several studies have investigated the effects of various climatic conditions (Fernández-Mendoza et al, 2011;Grande et al, 2017;Leavitt et al, 2016;Marini, Nascimbene, & Nimis, 2011;Peksa & Škaloud, 2011;G. Singh et al, 2017).…”

Quantifying the climatic niche of symbiont partners in a lichen symbiosis indicates mutualist‐mediated niche expansions

“…cyanobacteria: Rikkinen et al 2002, Wirtz et al 2003, green algae: Doering and Piercey-Normore 2009, Dal Grande et al 2014, Singh et al 2017). On the one hand, several mycobiont species may associate with the same photobiont species, often forming so called lichen guilds (e.g.…”

“…Moreover, horizontal transfer of photobionts of the genus Trebouxia or the genus Asterochloris between different populations of mycobionts seems to have occurred with high ecological specificity both at a local-scale (Piercey-Normore 2006, Sork 2010, Peksa andŜkaloud 2011) and at larger scales of ecogeographic regions (Yahr et al 2006, Fernández-Mendoza et al 2011, Werth and Sork 2014. Mantel tests and phylogenetic signal; Yahr et al 2006, Peksa and Ŝkaloud 2011, Singh et al 2017; or 3) partitioning presence/absence variation for particular symbiont haplotypes onto environmental variables (e.g. photobionts or mycobionts) via categorical predictors for habitat and/or symbiotic partners (e.g.…”