High levels of endemism and local differentiation in the fungal and algal symbionts of saxicolous lecideoid lichens along a latitudinal gradient in southern South America

Abstract

Saxicolous, lecideoid lichenized-fungi have a cosmopolitan distribution but, being mostly cold adapted, are especially abundant in polar and high-mountain regions. To date, little is known of their origin or the extent of their trans-equatorial dispersal. Several mycobiont genera and species are thought to be restricted to either the northern or southern hemisphere, whereas others are thought to be widely distributed and occur in both hemispheres. However, these assumptions often rely on morphological analyses and lack supporting molecular genetic data. Also unknown is the extent of regional differentiation in the southern Polar Regions.An extensive set of lecideoid lichens (185) was collected along a latitudinal gradient at the southern end of South America, always staying in areas of subantarctic climate by increasing the elevation of the collecting sites with decreasing latitude. The investigated specimens were brought into a global context by including Antarctic and cosmopolitan sequences from other studies. For each symbiont three markers were used to identify intraspecific variation (mycobiont: ITS, mtSSU, RPB1; photobiont: ITS, psbJ-L, COX2). For the mycobiont the saxicolous genera Lecidea, Porpidia, Poeltidea and Lecidella and their photobionts Asterochloris and Trebouxia were phylogenetically revised. The resultsshow for several globally distributed species groups geographically highly differentiated subclades, classified as operational taxonomical units (OTUs), which were assigned to the different regions of southern South America (sSA). Further, for sSA, several small endemic and well supported clades were detected at the species level for both symbionts. Keywords subantarctic subregion, pioneer vegetation on rock, global distribution, local differentiation, endemism, glacial refugia Dedicated to Hannes Hertel on his 80 th birthday in appreciation of his life-long investigation of lecideoid lichens. nM of each of the four dNTPs, 0.3 µM of each primer and about 1 ng genomic DNA.For each symbiont, three markers were amplified and sequenced with the primers presented in Table S3 with conditions as described in Ruprecht et al. (2014) and Ruprecht et al. (2016). Unpurified PCRproducts were sent to Eurofins Genomics/Germany for sequencing. Mycobiont:The internal transcribed spacer region of the nuclear ribosomal DNA (ITS) was amplified for all specimens. Furthermore, the mitochondrial small subunit (mtSSU) and the large subunit of DNA-dependent RNA polymerase 2 (RPB1) were amplified for the Lecidea/Porpidida/Poeltidea group.

Myco- and photobiont associations in crustose lichens in the McMurdo Dry Valleys (Antarctica) reveal high differentiation along an elevational gradient

“…We also amplified additional markers: for the mycobionts the mitochondrial small subunit (mtSSU) and the low-copy protein coding marker RPB1 and, for the photobionts, the chloroplastencoded intergenic spacer (psbJ-L) and part of the cytochrome oxidase subunit 2 gene (COX2). This was done using newly developed specific primers and PCR-protocols in our project-framework (Ruprecht et al 2019).…”

“…For amplifying nrITS of the mycobiont we used the primers ITS1 (White et al 1990), ITS1F (Gardes and Bruns 1993), ITS1L Ruprecht et al 2014). For the marker mtSSU the primers CU6 (https://nature.berkeley.edu/brunslab/tour/primers.html), mrSSU1 (Zoller et al 1999), mtSSU for2 (Ruprecht et al 2010) and mtSSU rev2 (Ruprecht et al 2010) and for RPB1, fRPB1-C rev (Matheny et al 2002), gRPB1-A for (Matheny et al 2002) and RPB1_for_Lec (Ruprecht et al 2019) were chosen. For the marker COX2, COXIIf2 and COXIIr (Lindgren et al 2014) and COX sense (Ruprecht et al 2019) and for psbJ-L, psbF (Werth and Sork 2010), psbL-sense and psbJ-antisense (Ruprecht et al 2014) were used.…”

“…For the marker COX2, COXIIf2 and COXIIr (Lindgren et al 2014) and COX sense (Ruprecht et al 2019) and for psbJ-L, psbF (Werth and Sork 2010), psbL-sense and psbJ-antisense (Ruprecht et al 2014) were used. All reactions were performed as described in (Ruprecht et al 2019). Unpurified PCR-products were sent to Eurofins Genomics/Germany for sequencing.…”

“…The backbone is not supported and therefore the topology will not be discussed. with numbers were included in our system of assigning the haplotypes to the appropriate OTUs (Ruprecht et al 2019) and therefore renamed.…”

“…Most of the lichens analyzed here belong to the 'lecideoid' lichen group (Hertel 1984) and these species are assigned to the generic name Lecidea sensu Zahlbruckner (1925) but they do not necessarily belong to the genus in its strict sense. Due to their inconspicous growth form, distinguishable only by a few small morphological traits such as spore size and ascus-type, the identification of these lichens is difficult even under best growing conditions (Ruprecht et al 2019). Extreme climate conditions in cold deserts result in reduced development of the thallus such as chasmolithic growth, a lack of ascomata or sparsely developed ascospores, all features that hamper identification and even the detection of the specimens in the vast landscape (Hertel 2009;Ruprecht et al 2010).…”