Biology subjects

Thor, G.

Publications and source records attributed to Thor, G..

2 recordsLinked to original sources

bioRxiv2025

Does more data solve the problem of deep support? A phylogenomic approach to clarifying evolutionary relationships in the Lecanoraceae

The family Lecanoraceae is one of the most diverse groups within Lecanoromycetes, yet its internal relationships have remained unresolved despite previous multilocus studies. Here we present the first phylogenomic reconstruction of the family, based on 1003 nuclear orthologous genes from 65 genome assemblies representing the major species groups and genera. Phylogenetic trees inferred from coalescent-based analyses, together with Quartet Sampling (QS) evaluation, confirm the monophyly of Lecanoraceae and recover several well-supported lineages. The Lecanora subfusca group is resolved as polyphyletic, comprising three major clades together with Zeora and Vainionora. Additional strongly supported lineages correspond to Glaucomaria s. lat., the MPRPS clade, and Lecidella s. lat., while Bryonora and Frutidella represent early-diverging members of the family. The L. fuscescens group and Miriquidica form a distinct lineage sister to Lecanoraceae, whereas Ramboldia (Ramboldiaceae) constitutes another sister family. Backbone support was generally improved, and QS analyses showed counter-support for only a few deep nodes, indicating a complex evolutionary history likely shaped by incomplete lineage sorting, hybridization, or rapid radiation. Our results demonstrate that genome-scale data improve the resolution of Lecanoraceae, but increasing the number of genes alone can not fully resolve the backbone relationships of the family.

molecular biology↗

bioRxiv2020

The plot thickens: haploid and triploid-like thalli, hybridization, and biased mating type ratios in Letharia

The study of the reproductive biology of lichen fungal symbionts has been traditionally challenging due to their complex and symbiotic lifestyles. Against the common belief of haploidy, a recent genomic study found a triploid-like signal in Letharia. Here, we used genomic data from a pure culture and from thalli, together with a PCR survey of the MAT locus, to infer the genome organization and reproduction in Letharia. We found that the read count variation in the four Letharia specimens, including the pure culture derived from a single sexual spore of L. lupina, is consistent with haploidy. By contrast, the L. lupina read counts from a thallus metagenome are triploid-like. Characterization of the mating-type locus revealed a conserved heterothallic configuration across the genus, along with auxiliary genes that we identified. We found that the mating-type distributions are balanced in North America for L. vulpina and L. lupina, suggesting widespread sexual reproduction, but highly skewed in Europe for L. vulpina, consistent with predominant asexuality. Taken together, we propose that Letharia fungi are heterothallic and typically haploid, and provide evidence that triploid-like individuals are rare hybrids between L. lupina and an unknown Letharia lineage, reconciling classic systematic and genetic studies with recent genomic observations.

evolutionary biology↗