Biodiversity Patterns and Ecological Preferences of the Photobionts Associated With the Lichen-Forming Genus Parmelia

Abstract

The worldwide, ecologically relevant lichen-forming genus Parmelia currently includes 41 accepted species, of which the Parmelia sulcata group (PSULgp) and the Parmelia saxatilis group (PSAXgp) have received considerable attention over recent decades; however, phycobiont diversity is poorly known in Parmelia s. lat. Here, we studied the diversity of Trebouxia microalgae associated with 159 thalli collected from 30 locations, including nine Parmelia spp.: P. barrenoae, P. encryptata, P. ernstiae, P. mayi, P. omphalodes, P. saxatilis, P. serrana, P. submontana, and P. sulcata. The mycobionts were studied by carrying out phylogenetic analyses of the nrITS. Microalgae genetic diversity was examined by using both nrITS and LSU rDNA markers. To evaluate putative species boundaries, three DNA species delimitation analyses were performed on Trebouxia and Parmelia. All analyses clustered the mycobionts into two main groups: PSULgp and PSAXgp. Species delimitation identified 13 fungal and 15 algal species-level lineages. To identify patterns in specificity and selectivity, the diversity and abundance of the phycobionts were identified for each Parmelia species. High specificity of each Parmelia group for a given Trebouxia clade was observed; PSULgp associated only with clade I and PSAXgp with clade S. However, the degree of specificity is different within each group, since the PSAXgp mycobionts were less specific and associated with 12 Trebouxia spp., meanwhile those of PSULgp interacted only with three Trebouxia spp. Variation-partitioning analyses were conducted to detect the relative contributions of climate, geography, and symbiotic partner to phycobiont and mycobiont distribution patterns. Both analyses explained unexpectedly high portions of variability (99 and 98%) and revealed strong correlations between the fungal and algal diversity. Network analysis discriminated seven ecological clusters. Even though climatic conditions explained the largest proportion of the variation among these clusters, they seemed to show indifference relative to climatic parameters. However, the cluster formed by P. saxatilis A/P. saxatilis B/Trebouxia sp. 2/Trebouxia sp. S02/Trebouxia sp. 3A was identified to prefer cold-temperate as well as humid summer environments.

Punctelia borreri and P. subrudecta (Parmeliaceae) associate with a partially overlapping pool of Trebouxia gelatinosa lineages

“…This evidence suggests that the two lichens are highly selective (sensu Beck et al 2002) for this phycobiont taxon across a large geographical range in the Northern Hemisphere that includes various bioclimatic and biogeographical areas. These results agree with other observations in which identical phycobiont strains associated with a single mycobiont in distant geographical areas (Fernández-Mendoza et al 2011;Garrido-Benavent et al 2020;Moya et al 2021). The fact that P. borreri and P. subrudecta usually reproduce by soredia might explain why these lichens retain the same microalgal species as their photosynthetic partner; however, genetic differentiation may still be occurring, for example, owing to intrathalline somatic mutations occurring during algal cell division (Dal Grande et al 2014).…”

“…Parmelia saxatilis (L.) Ach. and P. sulcata Taylor species complexes; Moya et al 2021), or in phylogeographical assessments based on large specimen sampling. For example, diverse Trebouxia species and infraspecific lineages were found in association with Cetraria aculeata (Schreb.)…”

Trebouxia lynnae sp. nov. (Former Trebouxia sp. TR9): Biology and Biogeography of an Epitome Lichen Symbiotic Microalga

“…The new species Trebouxia lynnae belongs to Trebouxia clade A (as shown here and in previous studies [ 5 , 6 , 9 , 10 , 31 , 86 ]) and was found to be a sister species of T. jamesii ( Figure 4 ). BI and ML analyses were topologically congruent and high posterior probabilities (PP) and bootstrap supports (BS) were obtained for all species-level lineages.…”

Ecolichenology of Eastern Ghats diversity against climatic fluctuations in Kolli Hills, India

“…the advancement of the lichen thallus over miniaturized and large-scale biological scales was clearly affected by the nearness of the two primary symbionts within the environment and by the portion of selectivity and specificity that either symbiont appears for each other (Moya et al 2021). Typically, commonly considered a versatile procedure of the mycobiont to colonize a more extensive extent of natural conditions, selecting the leading adjusted phycobiont (Muggia et al 2013).…”

“…The density of lichens is reassessed based on the morpho chemotic features and its updated taxonomic keys. The impact of the susceptibility of lichen species to abiotic and biotic changes was influenced by the ability of the thallus accumulation within challenging environments through physiological adhesiveness (Kodnik et al 2015;Moya et al 2021). Most corticolous and saxicolous taxa were reported with multiple species rich in nature (Belguidoum et al 2022a,b).…”