Local representation of global diversity in a cosmopolitan lichen‐forming fungal species complex (Rhizoplaca, Ascomycota)

Abstract

Aim The relative importance of long-distance dispersal versus vicariance in determining the distribution of lichen-forming fungi remains unresolved. Here, we examined diversity and distributions in a cosmopolitan lichen-forming fungal species complex, Rhizoplaca melanophthalma sensu lato (Ascomycota), across a broad, intercontinental geographical distribution. We sought to determine the temporal context of diversification and the impacts of past climatic fluctuations on demographic dynamics within this group.Location Antarctica, Asia, Europe, North America and South America.Methods We obtained molecular sequence data from a total of 240 specimens of R. melanophthalma s.l. collected across five continents. We assessed the monophyly of candidate species using individual gene trees and a tree from a seven-locus concatenated data set. Divergence times and relationships among candidate species were evaluated using a multilocus coalescent-based species tree approach. Speciation probabilities were estimated using the coalescentbased species delimitation program bpp. We also calculated statistics on molecular diversity and population demographics for independent lineages.Main conclusions Our analyses of R. melanophthalma s.l. collected from five continents supported the presence of six species-level lineages within this complex. Based on current sampling, two of these lineages were found to have broad intercontinental distributions, while the other four were limited to western North America. Of the six lineages, five were found on a single mountain in the western USA and the sixth occurred no more than 200 km away from this mountain. Our estimates of divergence times suggest that Pleistocene glacial cycles played an important role in species diversification within this group. At least three lineages show evidence of recent or ongoing population expansion.

DNA barcode identification of lichen-forming fungal species in the Rhizoplaca melanophthalma species-complex (Lecanorales, Lecanoraceae), including five new species

“…However, these candidate species were not formally described due to the limited geographical sampling. Increased geographic sampling, including collections from Antarctica, Central Asia, Europe, and North and South America, along with additional genetic markers corroborate the previously recognized candidate species (Leavitt et al 2013).…”

“…In spite of a high degree of morphological and chemical variation within this species complex, most of the candidate species identified in this study were morphologically and/or chemically polymorphic, and diagnostic morphological/chemical characters were not identified for the majority of the independent species-level lineages (Leavitt et al 2011a). Recently, additional data, including broader geographic sampling and three additional genetic markers, provide additional support that the candidate species identified in Leavitt et al (2011a) represent species-level lineages (Leavitt et al 2013).…”

“…In this study, we used the ITS alignment and phylogeny reported in Leavitt et al (2013) (Fig. 2A; supplementary file 1; TreeBase ID 13903).…”

“…This data consisted of 228 sequences and 524 aligned nucleotide position characters. A full description of multiple sequence alignment and phylogenetic reconstruction methods is given in Leavitt et al (2013). In short, the multiple sequence alignment was performed using the program MAFFT v6 (Katoh et al 2005;Katoh and Toh 2008), and phylogenetic relationships were estimated using maximum likelihood using the program RAxML v7.2.8 (Stamatakis 2006;Stamatakis et al 2008).…”

“…Therefore, accurate specimen identification may have important implications for bio-monitoring and pharmaceutical research using R. melanophthalma s.l. Furthermore, several lineages within the R. melanophthalma species-complex are broadly distributed (Leavitt et al 2013), and these may potentially serve as valuable groups for assessing dispersal capacity and landscape-level genetics in response to changing climatic conditions, assuming accurate specimen identification. Given the overall importance of accurate specimen identification, including phenotypically cryptic lineages, the objectives of this study are to (1) formally describe five new species within this group and (2) provide a reference DNA sequence database using the ITS marker as a DNA barcode for identifying species within this complex.…”