The Helvella corium species complex: Phylogeny, species delimitation and distribution in the Nordic countries

• Main Author: Løken, Solveig Bua
• Format: Master Thesis
• Language: Norwegian Bokmål
• Published: 2018
• Subjects: Arctic; Norway
• Online Access: http://hdl.handle.net/10852/64861; http://urn.nb.no/URN:NBN:no-67386

This project represents an in-depth systematic study of a pseudo-cryptic species complex, all species formerly nested under the name Helvella corium. Species limits and evolutionary relationships of this morphospecies complex were re-assessed, using an extended set of genetic markers (LSU, HSP, RPB2, EF-1α and 5.8S for 47 specimens). Following a multispecies coalescent approach, the newly developed software STACEY was implemented to delineate evolutionary species. Considerable interspecific differences in evolutionary rates were observed in ribosomal loci, suggesting careful use of these regions in delimitation of Helvella species. All identified species were supported with morphological characters to aid in non-molecular species discrimination. In order to assess the species’ distribution in the Nordic countries, all specimens stored under the name Helvella corium in the Nordic herbaria were examined and barcoded with HSP. This was supplemented with fresh collections from fieldwork in primarily under-studied alpine regions of Norway in 2015-2017. Altogether, 469 out of 496 specimens were successfully barcoded. The Helvella corium morphospecies complex consists of seven phylogenetically distinct species, nested in two divergent and strongly supported evolutionary lineages. In the alpina-corium lineage we find H. corium, H. alpina and H. pseudoalpina sp. nov. The alpestris-nannfeldtii lineage consists of H. alpestris, H. macrosperma and H. nannfeldtii. Helvella alpicola is supported as sister to the alpestris-nannfeldtii lineage. Helvella corium is the only species that occur in temperate, boreal and arctic-alpine biomes. The other six species seem restricted to the arctic-alpine biome where they occupy different but overlapping habitats. This project highlights how modern biosystematics, with the use of molecular markers and advanced statistical tools, can extend our knowledge of fungal diversity and distribution patterns. In addition, molecular systematics has implications for other fields of biological sciences, such as ecology and conservation biology. By re-examining this species complex in a genealogical framework, we can begin to understand their specific ecological roles in natural ecosystems and evaluate their needs for conservation.