Publications by authors named "Rachel A Swenie"

5 Publications

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Pyrophilous fungi detected after wildfires in the Great Smoky Mountains National Park expand known species ranges and biodiversity estimates.

Mycologia 2020 Jul-Aug;112(4):677-698. Epub 2020 Jun 4.

Department of Plant and Microbial Biology, University of California , Berkeley, California 94520-3102.

Following a late fall wildfire in 2016 in the Great Smoky Mountains National Park, pyrophilous fungi in burn zones were documented over a 2-y period with respect to burn severity and phenology. Nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) barcodes were obtained to confirm morphological evaluations. Forty-one taxa of Ascomycota and Basidiomycota were identified from burn sites and categorized as fruiting only in response to fire or fruiting enhanced by fire. Twenty-two species of Pezizales (Ascomycota) were among the earliest to form ascomata in severe burn zones, only one of which had previously been documented in the Great Smoky Mountains National Park. Nineteen species of Basidiomycota, primarily Agaricales, were also documented. Among these, only five species (, and ) were considered to be obligate pyrophilous taxa, but fruiting of two additional taxa ( and ) was clearly enhanced by fire. was an early colonizer of severe burn sites and persisted through the winter of 2017 and into spring and summer of 2018, often appearing in close association with seedlings. Fruiting of pyrophilous fungi peaked 4-6 mo post fire then diminished, but some continued to fruit up to 2.5 y after the fire. In all, a total of 27 previously unrecorded taxa were added to the All Taxa Biodiversity Inventory (ATBI) database (~0.9%). Most pyrophilous fungi identified in this study are either cosmopolitan or have a Northern Hemisphere distribution, but cryptic endemic lineages were detected in and . One new combination, var. f. , is proposed.
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http://dx.doi.org/10.1080/00275514.2020.1740381DOI Listing
June 2020

Six new species and reports of (Cantharellales) from eastern North America.

MycoKeys 2018 30(42):35-72. Epub 2018 Nov 30.

Department of Ecology and Evolutionary Biology, 569 Dabney Hall, University of Tennessee, Knoxville, TN 37996, USA University of Tennessee Knoxville United States of America.

Five species of have been generally recognized from eastern North America based on morphological recognition: , , and varieties, , and . Other unique North American species, such as and , are either illegitimately named or considered synonymous with European taxa. Here, seventeen phylogenetic species of are detected from eastern North America based on a molecular phylogenetic survey of ITS sequences from herbarium collections and GenBank data, including environmental sequences. Based on current distribution results, sixteen of these species appear endemic to North America. Of these, six species are described as new: , , , , , and . Geographic range extensions and taxonomic notes are provided for five additional species recently described as new from eastern North America. A new name, , is proposed for Banning ex Peck, non Valenti. Overall, species of are best recognized by a combination of morphological and molecular phylogenetic analyses. Taxonomic descriptions are provided for seventeen species, including epitype designations for , , and , taxa described more than 100 years ago, and molecular annotation of the isotype of . Photographs and a key to eastern North American species are presented.
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http://dx.doi.org/10.3897/mycokeys.42.27369DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6286385PMC
November 2018

Revision of pyrophilous taxa of Pholiota described from North America reveals four species-P. brunnescens, P. castanea, P. highlandensis, and P. molesta.

Mycologia 2018 Nov-Dec;110(6):997-1016. Epub 2018 Nov 27.

a Department of Ecology and Evolutionary Biology , University of Tennessee , Dabney 569, Knoxville , Tennessee 37996-1610.

A systematic reevaluation of North American pyrophilous or "burn-loving" species of Pholiota is presented based on molecular and morphological examination of type and historical collections. Confusion surrounds application of the names P. brunnescens, P. carbonaria, P. castanea, P. fulvozonata, P. highlandensis, P. molesta, and P. subsaponacea, with multiple names applied to a single species and multiple species described more than once. Molecular annotations using nuc rDNA ITS1-5.8S-ITS2 (internal transcribed spacer [ITS] barcode) and RPB2 (RNA polymerase II second largest subunit) are used to aid in application of these names in a phylogenetic context. Based on ITS molecular annotations of 13 types, the following heterotypic synonymies are proposed: P. highlandensis (syn. P. carbonaria and P. fulvozonata); P. molesta (syn. P. subsaponacea); and P. brunnescens (syn. P. luteobadia). In addition, we observed that the species P. castanea, known previously only from the type collection in Tennessee, is found commonly on burned sites near the Gulf Coast and other southeast regions of the United States. Overall, the pyrophilous trait is evolutionarily derived in Pholiota. Endophytic and endolichenic stages were deduced for P. highlandensis, the most widely distributed of the pyrophilous Pholiota. As a result, we introduce the "body snatchers" hypothesis that explains the maintenance of some pyrophilous fungi in ecosystems as endophytes and/or endolichenic fungi. Photographs, taxonomic descriptions, and a dichotomous key to pyrophilous species of Pholiota that occur in North America are presented.
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http://dx.doi.org/10.1080/00275514.2018.1516960DOI Listing
April 2019

Stable isotope analyses reveal previously unknown trophic mode diversity in the Hymenochaetales.

Am J Bot 2018 11 26;105(11):1869-1887. Epub 2018 Oct 26.

Department of Ecology and Evolutionary Biology, University of Tennessee, 1416 Circle Drive, Knoxville, Tennessee, 37996, USA.

Premise Of The Study: The Hymenochaetales are dominated by lignicolous saprotrophic fungi involved in wood decay. However, the group also includes bryophilous and terricolous taxa, but their modes of nutrition are not clear. Here, we investigate patterns of carbon and nitrogen utilization in numerous non-lignicolous Hymenochaetales and provide a phylogenetic context in which these non-canonical ecological guilds arose.

Methods: We combined stable isotope analyses of δ C and δ N and phylogenetic analyses to explore assignment and evolution of nutritional modes. Clustering procedures and statistical tests were performed to assign trophic modes to Hymenochaetales and test for differences between varying ecologies. Genomes of Hymenochaetales were mined for presence of enzymes involved in plant cell wall and lignin degradation and sucrolytic activity.

Key Results: Three different trophic clusters were detected - biotrophic, saprotrophic, and a second biotrophic cluster including many bryophilous Hymenochaetales and mosses. Non-lignicolous Hymenochaetales are generally biotrophic. All lignicolous Hymenochaetales clustered as saprotrophic and most terricolous Hymenochaetales clustered as ectomycorrhizal. Overall, at least 15 species of Hymenochaetales are inferred as biotrophic. Bryophilous species of Rickenella can degrade plant cell walls and lignin, and cleave sucrose to glucose consistent with a parasitic or endophytic life style.

Conclusions: Most non-lignicolous Hymenochaetales are biotrophic. Stable isotope values of many bryophilous Hymenochaetales cluster as ectomycorrhizal or in a biotrophic cluster indicative of parasitism or an endophytic life style. Overall, trophic mode diversity in the Hymenochaetales is greater than anticipated, and non-lignicolous ecological traits and biotrophic modes of nutrition are evolutionarily derived features.
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http://dx.doi.org/10.1002/ajb2.1183DOI Listing
November 2018

The Inocybe geophylla group in North America: a revision of the lilac species surrounding I. lilacina.

Mycologia 2018 May-Jun;110(3):618-634. Epub 2018 Jun 22.

a Department of Ecology and Evolutionary Biology , University of Tennessee , Hesler 332, Knoxville , Tennessee 37996-1610.

The Inocybe geophylla group is circumscribed based on phylogenetic analysis of DNA sequences largely sampled from North America and Europe. Twenty-nine phylogenetic species are uncovered after analysis of combined nuc 28S rDNA (28S) and RNA polymerase II second largest subunit (rpb2) DNA sequence data. Species in the I. geophylla group share the presence of a cortina, silky-fibrillose pileus and stipe, pruinose stipe apex, spermatic odor, thick-walled hymenial cystidia, and smooth amygdaliform or elliptical basidiospores. Within the group, as many as five phylogenetic species attributable to I. lilacina and allies form a strongly supported clade based on analysis of nuc ITS1-5.8S-ITS2 rDNA (ITS [internal transcribed spacer]), 28S, and rpb2 data. However, all lilac-colored species do not form a monophyletic group. Sufficient morphological and ecological data are present to document four of the I. lilacina subgroup species, two of which are described from North America as new: I. ionocephala and I. sublilacina. Inocybe lilacina is recircumscribed based on sequencing the holotype and is distributed in the eastern United States under pines and/or hardwoods. Inocybe pallidicremea is a widespread and common conifer associate in mostly northern parts of North America, to which the name I. lilacina was previously applied. Descriptions, photographs, line drawings, and a taxonomic key to lilac species in the I. lilacina subgroup from North America are provided. Well-documented collections, especially notes on gross morphology and ecology, are needed to continue to assess and describe the high taxonomic variation in the I. lilacina subgroup and its allies worldwide.
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http://dx.doi.org/10.1080/00275514.2018.1469880DOI Listing
July 2019