Gary A. Laursen

Beringian origins and cryptic speciation events in the fly agaric (Amanita muscaria).

Amanita muscaria sensu lato has a wide geographic distribution, occurring in Europe, Asia, Africa, Australia, New Zealand, and North, Central and South America. Previous phylogenetic work by others indicates three geographic clades (i.e. ‘Eurasian’, ‘Eurasian‐alpine’ and ‘North American’ groups) within A. muscaria. However, the historical dispersal patterns of A. muscaria remained unclear. In our project, we collected specimens from arctic, boreal and humid temperate regions in Alaska, and generated DNA sequence data from the protein‐coding beta‐tubulin gene and the internal transcribed spacer (ITS) and large subunit (LSU) regions of the ribosomal DNA repeat. Homologous sequences from additional A. muscaria isolates were downloaded from GenBank. We conducted phylogenetic and nested clade analyses (NCA) to reveal the phylogeographic history of the species complex. Although phylogenetic analyses confirmed the existence of the three above‐mentioned clades, representatives of all three groups were found to occur sympatrically in Alaska, suggesting that they represent cryptic phylogenetic species with partially overlapping geographic distributions rather than being allopatric populations. All phylogenetic species share at least two morphological varieties with other species, suggesting ancestral polymorphism in pileus and wart colour pre‐dating their speciations. The ancestral population of A. muscaria likely evolved in the Siberian–Beringian region and underwent fragmentation as inferred from NCA and the coalescent analyses. The data suggest that these populations later evolved into species, expanded their range in North America and Eurasia. In addition to range expansions, populations of all three species remained in Beringia and adapted to the cooling climate.

Evidence for strong inter- and intracontinental phylogeographic structure in Amanita muscaria, a wind-dispersed ectomycorrhizal basidiomycete

A growing number of molecular studies show that many fungi have phylogeographic structures and that their distinct lineages are usually limited to different continents. As a conservative test of the extent to which wind-dispersed mycorrhizal fungi may exhibit phylogeographic structure, we chose to study Amanita muscaria, a host-generalist, widespread, wind-dispersed fungus. In this paper, we document the existence of several distinct phylogenetic species within A. muscaria, based on multilocus DNA sequence data. According to our findings, A. muscaria has strong intercontinental genetic disjunctions, and, more surprisingly, has strong intracontinental phylogeographic structure, particularly within North America, often corresponding to certain habitats and/or biogeographic provinces. Our results indicate that the view of A. muscaria as a common, widespread, easily identifiable, ecologically plastic fungus with a wide niche does not correctly represent the ecological and biological realities. On the contrary, the strong associations between phylogenetic species and different habitats support the developing picture of ecoregional endemisms and relatively narrow to very narrow niches for some lineages.

Mycorrhizae from Denali National Park and Preserve, Alaska

Abstract Roots of 40 taxa of higher plants (Pteridophyta, Spermatophyta) from two alpine study sites in Denali National Park and Preserve in central Alaska were examined for their mycorrhizal colonization. We observed ectomycorrhizae on six species: Betulanana, Salixreticulata, Salixpolaris, Salixarctica, Polygonumviviparum, and Dryasoctopetala. Seven taxa, Cassiopetetragona, Empetrumnigrum, Ledumpalustre subsp. decumbens, Ledumpalustre subsp. groenlandicum, Loiseleuriaprocumbens, Vacciniumuliginosum and Vacciniumvitis–idaea (all Ericales), had ericoid mycorrhizae. One species, Arctostaphylosalpina, formed a typical arbutoid mycorrhiza. Two species (Sibbaldiaprocumbens and Aconitumdelphinifolium) showed well-developed VA mycorrhizae, whereas three species of plants (Lycopodiumclavatum, Sileneacaulis and Oxytropisscammaniana) had vesicles, but no arbuscules. The roots of 11 other plants (Lycopodiumclavatum, Lycopodiumselago, Sileneacaulis, Gentianaalgida, Lupinusarcticus, Oxytropisscammaniana, Pedicularislangsdorffii, Pediculariscapitata, Pedicularisverticillata, Artemisia sp. and Carexbigelowii) had a variety of intracellular colonizations which are referred to as dark septate fungi. No mycorrhizae were found on 12 other plants: Equisetumarvense, Equisetumvariegatum, Lycopodiumalpinum, Polygonumbistorta, Saxifragahieracifolia, Saxifragahirculus, Astragalusalpinus, Pediculariskanei, Petasitesfrigidus, Carexpodocarpa, Carexmicrochaeta and Poaarctica. A possible ecological role of dark septate fungi is discussed.

Molecular phylogenetic biodiversity assessment of arctic and boreal ectomycorrhizal Lactarius Pers. (Russulales; Basidiomycota) in Alaska, based on soil and sporocarp DNA

Despite the critical roles fungi play in the functioning of ecosystems, especially as symbionts of plants and recyclers of organic matter, their biodiversity is poorly known in high‐latitude regions. In this paper, we discuss the molecular diversity of one of the most diverse and abundant groups of ectomycorrhizal fungi: the genus Lactarius Pers. We analysed internal transcribed spacer rDNA sequences from both curated sporocarp collections and soil polymerase chain reaction clone libraries sampled in the arctic tundra and boreal forests of Alaska. Our genetic diversity assessment, based on various phylogenetic methods and operational taxonomic unit (OTU) delimitations, suggests that the genus Lactarius is diverse in Alaska, with at least 43 putative phylogroups, and 24 and 38 distinct OTUs based on 95% and 97% internal transcribed spacer sequence similarity, respectively. Some OTUs were identified to known species, while others were novel, previously unsequenced groups. Non‐asymptotic species accumulation curves, the disparity between observed and estimated richness, and the high number of singleton OTUs indicated that many Lactarius species remain to be found and identified in Alaska. Many Lactarius taxa show strong habitat preference to one of the three major vegetation types in the sampled regions (arctic tundra, black spruce forests, and mixed birch‐aspen‐white spruce forests), as supported by statistical tests of UniFrac distances and principal coordinates analyses (PCoA). Together, our data robustly demonstrate great diversity and nonrandom ecological partitioning in an important boreal ectomycorrhizal genus within a relatively small geographical region. The observed diversity of Lactarius was much higher in either type of boreal forest than in the arctic tundra, supporting the widely recognized pattern of decreasing species richness with increasing latitude.

Molecular diversity assessment of arctic and boreal Agaricus taxa

We provide a phylogenetic diversity assessment study in genus Agaricus as part of our ongoing work to saturate ITS and LSU rDNA sequence diversity of soil-dwelling fungi in Alaska. Pairwise sequence similarity-based groupings and statistical parsimony analyses were applied to delimit operational taxonomic unit (OTU) and were compared to results of full phylogenetic analyses. Our results show that the proportion of section Arvenses taxa is particularly high in the boreal forest and hypo-arctic (low arctic) regions, whereas the genus is represented by section Agaricus in high arctic habitats. Furthermore our findings suggest that the commercially important A. bisporus occurs naturally in the boreal region of interior Alaska, substantially expanding the known northern limit of the species. Delimitations of OTU varied greatly with different methods. In general 95% similarity-based grouping proved to be the least sensitive method, often resulting in section- and subsection-level groups. The 95% connection-limit statistical parsimony separated far more groups. The 98% similarity-based groups and the 98% connection limit networks recognized respectively 11 and 13 OTU containing our specimens. The 98% connection limit statistical parsimony was the only method in which all recognized OTU consisted of members grouped by branches with significant (> .95) posterior probabilities, providing an independent support for the groups. Our results also point out that considerable additional efforts will be needed to elucidate the evolution of this diverse genus and to assess its phylogenetic diversity, given that most taxa in our analyses could not be placed convincingly within well characterized species using ITS/LSU data.

Phylogenetic and ecological analyses of soil and sporocarp DNA sequences reveal high diversity and strong habitat partitioning in the boreal ectomycorrhizal genus Russula (Russulales; Basidiomycota)

SUMMARY *Although critical for the functioning of ecosystems, fungi are poorly known in high-latitude regions. Here, we provide the first genetic diversity assessment of one of the most diverse and abundant ectomycorrhizal genera in Alaska: Russula. *We analyzed internal transcribed spacer rDNA sequences from sporocarps and soil samples using phylogenetic methods, operational taxonomic unit (OTU) delimitations and ordinations to compare species composition in various types of boreal forest. *The genus Russula is highly diverse in Alaska, with at least 42 nonsingleton OTUs (soil) and 50 phylogroups (soil + sporocarp). Russula taxa showed strong habitat preference to one of the two major forest types in the sampled regions (black spruce and birch-aspen-white spruce), and some preference for soil horizon. *Our results show that the vast majority of Russula species are present in the soil samples, although some additional taxa are expected to be found with extended sampling. OTU diversity in black spruce forests was only one-third of the diversity observed in mixed upland forests. Our findings suggest that some of the diversity is niche based, especially along host and successional axes, because most OTUs predictably occurred in specific habitats, regardless of geographical location.

Mycorrhizal Assessment of Vascular Plants from Subantarctic Macquarie Island

Roots of 40 taxa of vascular plants from subantarctic Macquarie Island were examined to determine their mycorrhizal status. Samples comprised 36 flowering plant taxa (Spermatophyta) from 16 families, and 4 nonflowering plant taxa (Pteridophyta) from 4 families. No arbutoid, ericoid, or ectomycorrhizae were observed, nor did we collect the fruiting bodies of any fungi whose presence would indicate or suggest the presence of ectomycorrhizal associations. Fifteen of the plants examined showed vesicles, but vesicles and arbuscles were observed in only three plants: Hydrocotyle novae-zeelandiae (Apiaceae), Pleurophyllum hook

Frequent circumarctic and rare transequatorial dispersals in the lichenised agaric genus Lichenomphalia (Hygrophoraceae, Basidiomycota)

Species of the genus Lichenomphalia are mostly restricted to arctic-alpine environments with the exception of Lichenomphalia umbellifera which is also common in northern forests. Although Lichenomphalia species inhabit vast regions in several continents, no information is available on their genetic variation across geographic regions and the underlying population-phylogenetic patterns. We collected samples from arctic and subarctic regions, as well as from newly discovered subantarctic localities for the genus. Phylogenetic, nonparametric permutation methods, and coalescent analyses were used to assess phylogeny and population divergence and to estimate the extent and direction of gene flow among distinct geographic populations. All known species formed monophyletic groups, supporting their morphology-based delimitation. In addition, we found two subantarctic phylogenetic species (Lichenomphalia sp. and Lichenomphalia aff. umbellifera), of which the latter formed a well-supported sister group to L. umbellifera. We found no significant genetic differentiation among conspecific North American and Eurasian populations in Lichenomphalia. We detected high intercontinental gene flow within the northern polar region, suggesting rapid (re)colonisation of suitable habitats in response to climatic fluctuations and preventing pronounced genetic differentiation. On the other hand, our phylogenetic analyses suggest that dispersal between northern circumpolar and subantarctic areas likely happened very rarely and led to the establishment and subsequent divergence of lineages. Due to limited sampling in the Southern Hemisphere, it is currently uncertain whether the northern lineages occur in Gondwanan regions. On the other hand, our results strongly suggest that the southern lineages do not occur in the circumpolar north. Although rare transequatorial dispersal and subsequent isolation may explain the emergence of at least two subantarctic phylogenetic species lineages in Lichenomphalia, more samples from the Southern Hemisphere are needed to better understand the phylogeographic history of the genus.

Myxomycetes of subantarctic Macquarie Island

Macquarie Island is an oceanic island located 1000 km south-east of Tasmania. The island, which lies close to but north of the Antarctic Convergence, is the southernmost island in the world with a fairly complete cover of vegetation. However, the vascular flora is impoverished and consists of only 46 species. During the period of late January to late April of 1995, 412 field collections of myxomycetes, representing at least 22 species in 11 genera, were obtained during the course of an intensive survey of fungal biodiversity on Macquarie Island. Moist-chamber cultures prepared with various types of plant debris yielded only 14 collections, but this total included three additional species and two additional genera. All but four of the species we recorded from the island are new records for the South Polar Region. Most field collections were associated with Stilbocarpa polaris (Araliaceae) and Pleurophyllum hookeri (Asteraceae), the usual dominants in the herbfield communities that commonly occur on upper beach slopes and coastal terraces. Trichia verrucosa (80 collections), Diderma alpinum (78) and Craterium leucocephalum (59) were the most consistently abundant myxomycetes. Other species represented by ≥15 collections were Didymium cf. dubium, Collaria lurida, Lamproderma arcyrioides and Didymium macquariense. The latter is a species new to science that was described from material collected during the present study. All of the species of myxomycetes now known to occur on Macquarie Island are members of the Trichiales, Physarales, Stemonitales or Echinosteliales; no member of the Liceales or Ceratiomyxales was ever collected.

Lichenicolous Fungi from Central Alaska: New Records and Range Extensions

Abstract Twenty-seven species of lichenicolous fungi (five of which are lichenized) are reported from Interior Alaska. Arthophacopsis parmeliarum (Sommerf.) Arnold, Capronia peltigerae (Fuckel) D. Hawksw., Merismatium heterophractum (Nyl.) Vouaux, Phomapeltigerae (P. Karst.) D. Hawksw., Roselliniella peltigericola D. Hawksw. & Miadlikowska, and Stigmidium pseudopeltideae Cl. Roux & Triebel are reported from North America for the first time. Corticifraga peltigerae (Nyl.) D. Hawksw. & R. Sant., Refractohilum peltigerae (Keissl.) D. Hawksw., and Vezdaea acicularis Coppins are here reported new to the United States.