Steven D. Leavitt

Steven D. Leavitt
Brigham Young University - Provo Main Campus | BYU · Department of Biology

PhD

About

192
Publications
74,618
Reads
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8,191
Citations
Citations since 2017
85 Research Items
5695 Citations
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201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
Additional affiliations
September 2013 - August 2016
Field Museum of Natural History
Position
  • Postdoctoral scientist
September 2013 - September 2015
University of Chicago
Position
  • Postdoctoral Scientist
January 2013 - August 2013
Brigham Young University - Provo Main Campus
Position
  • Research Associate

Publications

Publications (192)
Preprint
Full-text available
Aneuraceae is the largest family of the simple thalloid liverworts. Despite simple morphological features, this family is well-known for its unique ecology, cryptic diversity, and species-rich lineages. In this study, we explored the evolutionary history and diversification of the Aneuraceae. Investigating the effects of fossil calibrations on dive...
Preprint
Full-text available
Lichens have been reappraised as self-sustaining and long-living ecosystems in which a multiplicity of microorganisms are housed, in addition to the main symbiotic partners. Lichen-associated microfungi can frequently occur cryptically, and their species diversity has recently been more fully elucidated by DNA metabarcoding studies and culture isol...
Article
Two new species belonging to the lichen genus Anaptychia are described from western North America. Anaptychia nevadensis is superficially similar to the Eurasian A. desertorum but is distinguished by having longer ascospores, in producing scant pruina only near the lobe tips, and in regularly producing variolaric acid. Anaptychia roemerioides is de...
Article
Biomonitoring studies evaluating air quality via airborne element accumulation patterns in lichens typically control variability by focusing on narrow geographic regions and short time windows. Using samples of the widespread “rock‐posy” lichen sampled across the Intermountain Region of the United States, we investigate whether accumulation pattern...
Article
There are growing numbers of lichens observed outside their expected distributions. A recent discovery of Xanthoria parietina in Provo, Utah, USA is added to that list. Other individuals of this species have been noted in inland western United States, but this specimen was believed to be the first sighting of X. parietina in the Great Basin. Herbar...
Article
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In this study, two new species, Peltula confusa Q.X. Yang & X.L. Wei, sp. nov., growing in a dry microenvironment within a semi-humid area, and Peltula subpatellata Q.X. Yang & X.L. Wei, sp. nov., occurring in arid and semi-arid regions, are described. In addition, two species, P. polyspora (Tuck.) Wetmore and P. obscuratula (Nyl.) Poelt ex Egea, a...
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Subalpine habitats in sky islands in the Southwestern USA are currently facing large-scale transformations. Lichens have widely been used as bioindicators of environmental change. On the Colorado Plateau, fruticose lichens occur in patchy, disconnected populations, including unique lichen-draped conifer sites in subalpine forests in the La Sal Moun...
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Biodiversity inventories are important for informing land management strategies, conservationefforts, and for biomonitoring studies. For many organismal groups, including lichens,comprehensive, accurate inventories are challenging due to the necessity of taxonomic expertise,limitations in sampling protocols, and the commonplace occurrence of morpho...
Article
Twenty-five North American lichens are issued in Fascicle VIII of the "Anderson and Shushan: Lichens of Western North America" series, numbers 176-200. This fascicle is comprised of material representing specimens from the Rhizoplaca melanophthalma aggregate, including the vagrant taxa R. arbuscula, R. haydenii, and R. idahoensis; two collections r...
Article
Lichens are well-known examples of complex symbiotic associations between organisms from different Kingdoms. Microfungi in particular, establish diverse associations with the hosting lichen thallus, as species-specific parasites or transient co-inhabitants. The whole community of lichen-associated fungi constitute the ‘lichen mycobiome’ and compris...
Article
While advances in sequencing technologies have been invaluable for understanding evolutionary relationships, increasingly large genomic data sets may result in conflicting evolutionary signals which are often caused by biological processes, including hybridization. Hybridization has been detected in a variety of organisms, influencing evolutionary...
Preprint
Full-text available
Molecular sequence data has transformed the field of lichen taxonomy and provided crucial insight into evolutionary relationships. However, DNA obtained from standard extraction methodologies may not yield sufficient high-quality DNA to successfully perform high-throughput sequencing. Furthermore, standard DNA extraction protocols often, require th...
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Robust species delimitations provide a foundation for investigating speciation, phylogeography, and conservation. Here we attempted to elucidate species boundaries in the cosmopolitan lichen-forming fungal taxon Lecanora polytropa. This nominal taxon is morphologically variable, with distinct populations occurring on all seven continents. To delimi...
Article
The Colorado River and its tributaries on the Colorado Plateau are home to unique desert river ecosystems and changing environmental conditions. Within this region, the Glen Canyon National Recreation Area (GCNRA) is composed of rugged, high desert terrain and is managed by the United States National Park Service as both a recreational and conserva...
Article
Full-text available
Fungal–algal relationships—both across evolutionary and ecological scales—are finely modulated by the presence of the symbionts in the environments and by the degree of selectivity and specificity that either symbiont develop reciprocally. In lichens, the green algal genus Trebouxia Puymaly is one of the most frequently recovered chlorobionts. Treb...
Article
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Lichen associations are overwhelmingly supported by carbon produced by photosynthetic algal symbionts. These algae have diversified to occupy nearly all climates and continents; however, we have a limited understanding of how their climatic niches have evolved through time. Here we extend previous work and ask whether phylogenetic signal in, and th...
Article
Full-text available
Species delimitation among closely related species is challenging because traditional phenotype-based approaches, for example, using morphology, ecological, or chemical characteristics, may not coincide with natural groupings. With the advent of high-throughput sequencing, it has become increasingly cost-effective to acquire genome-scale data which...
Article
Full-text available
Lichens are symbiotic associations resulting from interactions among fungi (primary and secondary mycobionts), algae and/or cyanobacteria (primary and secondary photobionts), and specific elements of the bacterial microbiome associated with the lichen thallus. The question of what is a species, both concerning the lichen as a whole and its main fun...
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Lichens are major components of high altitude/latitude ecosystems. However, accurately characterizing their biodiversity is challenging because these regions and habitats are often underexplored, there are numerous poorly known taxonomic groups, and morphological variation in extreme environments can yield conflicting interpretations. Using an iter...
Article
Based on field collections made during the summers of 1987, 1988, and 1989, we report 159 species of lichens in 69 genera for the Jarbidge Wilderness Area (JWA) and adjacent Forest Service lands, located in the northern Great Basin, USA. Specimens were collected at 25 sites, distributed across the JWA along with two additional sites north of the wi...
Article
Full-text available
The genus Xanthoparmelia is the largest genus of lichen- forming fungi with about 800 species worldwide. Xanthoparmelia is also common in the deserts of central Mexico, but only a few molecular studies exist on its species’ diversity in this region. In this study, we sampled 38 Xanthoparmelia species from around the world including species from the...
Article
Full-text available
In show caves, artificial lighting is intended to illuminate striking cave formations for visitors. However, artificial lighting also promotes the growth of novel and diverse biofilm communities, termed lampenflora, that obtain their energy from these artificial light sources. Lampenflora, which generally consist of cyanobacteria, algae, diatoms, a...
Article
Full-text available
Lichens are classic models of symbiosis, and one of the most frequent nutritional modes among fungi. The ecologically and geographically widespread lichen-forming algal (LFA) genus Trebouxia is one of the best-studied groups of LFA and associates with over 7000 fungal species. Despite its importance, little is known about its diversification. We sy...
Preprint
Full-text available
Species delimitation among closely related species is challenging because traditional phenotype-based approaches, e.g., morphology, ecological, or chemical characteristics, often produce conflicting results. With the advent of high-throughput sequencing, it has become increasingly cost-effective to acquire genome-scale data which can resolve previo...
Article
Full-text available
Background Regions within the nuclear ribosomal operon are a major tool for inferring evolutionary relationships and investigating diversity in fungi. In spite of the prevalent use of ribosomal markers in fungal research, central features of nuclear ribosomal DNA (nrDNA) evolution are poorly characterized for fungi in general, including lichenized...
Article
Full-text available
Parmeliaceae is the largest family of lichen-forming fungi with a worldwide distribution. We used a target enrichment data set and a qualitative selection method for 250 out of 350 genes to infer the phylogeny of the major clades in this family including 81 taxa, with both subfamilies and all seven major clades previously recognized in the subfamil...
Article
Full-text available
Lichens have traditionally been considered the symbiotic phenotype from the interactions of a single fungal partner and one or few photosynthetic partners. However, lichen symbioses have been shown to be far more complex and may include a wider range of other interacting organisms, including non-photosynthetic bacteria, accessory fungi, and algae....
Article
Abstract Lichens provide valuable systems for studying symbiotic interactions. In lichens, these interactions are frequently described in terms of availability, selectivity and specificity of the mycobionts and photobionts towards one another. The lichen-forming, green algal genus Trebouxia Puymaly is among the most widespread photobiont, associati...
Article
Two new species belonging to the common and widespread lichen genus Physcia are described from western North America. One of these, P. occidentalis, is an obligately saxicolous species that reproduces by fragmentation, primarily through the production of largely terminal blastidia. Only a single very immature apothecium was observed among all colle...
Article
Full-text available
Lichens of the Ramalina siliquosa complex dominate seashore cliffs in Europe and South-East Asia, but their taxonomy has been vigorously debated for over a century. On many cliffs, they exhibit a bewildering zonation of chemotypes that resembles the classic zonation of organisms that occupy the littoral zone below. Do the chemotypes represent separ...
Article
The La Sal Mountains in eastern Utah, USA, contain the only alpine habitat on the Colorado Plateau in Utah. These unique sky island alpine communities are vulnerable to a wide range of disturbances, including factors associated with the recent introduction of mountain goats (O. americanus). In order to monitor the potential impact of O. americanus,...
Article
Lichens provide valuable systems for studying symbiotic interactions. In lichens, these interactions are frequently described in terms of availability, selectivity and specificity of the mycobionts and photobionts towards one another. The lichen-forming, green algal genus Trebouxia Puymaly is among the most widespread photobiont, associating with a...
Preprint
Full-text available
Lichens have traditionally been considered the symbiotic phenotype from the interactions of a single fungal partner and one or few photosynthetic partners. However, the lichen symbiosis has been shown to be far more complex and may include a wide range of other interacting organisms, including non-photosynthetic bacteria, accessory fungi, and algae...
Article
Full-text available
Advancements in molecular genetics have revealed that hybridization may be common among plants, animals, and fungi, playing a role in evolutionary dynamics and speciation. While hybridization has been well-documented in pathogenic fungi, the effects of these processes on speciation in fungal lineages with different life histories and ecological nic...
Preprint
Full-text available
Background: Regions within the nuclear ribosomal operon are a major tool for inferring evolutionary relationships and investigating diversity in fungi. In spite of the prevalent use of ribosomal markers in fungal research, central features of nuclear ribosomal DNA (nrDNA) evolution are poorly characterized for fungi in general, including lichenized...
Preprint
Full-text available
Background: Regions within the nuclear ribosomal operon are a major tool for inferring evolutionary relationships and investigating diversity in fungi. In spite of the prevalent use of ribosomal markers in fungal research, central features of nuclear ribosomal DNA (nrDNA) evolution are poorly characterized for fungi in general, including lichenized...
Article
Full-text available
Abstract Dothideomycetes is the most diverse fungal class in Ascomycota and includes species with a wide range of lifestyles. Previous multilocus studies have investigated the taxonomic and evolutionary relationships of these taxa but often failed to resolve early diverging nodes and frequently generated inconsistent placements of some clades. Here...
Article
Full-text available
Natural history collections, including name-bearing type specimens, are an important source of genetic information. These data can be critical for appropriate taxonomic revisions in cases where the phylogenetic position of name-bearing type specimens needs to be identified, including morphologically cryptic lichen-forming fungal species. Here, we u...
Preprint
Full-text available
Regions within the nuclear ribosomal operon are a major tool for inferring evolutionary relationships and investigating diversity in fungi. In spite of the prevalent use of ribosomal markers in fungal research, central features of nuclear ribosomal DNA (nrDNA) evolution are poorly characterized for fungi in general, including lichenized fungi. The...
Preprint
Full-text available
Background Regions within the nuclear ribosomal operon are a major tool for inferring evolutionary relationships and investigating diversity in fungi. In spite of the prevalent use of ribosomal markers in fungal research, central features of nuclear ribosomal DNA (nrDNA) evolution are poorly characterized for fungi in general, including lichenized...
Article
Lichen communities in many National Parks are diverse and perform essential but often poorly understood ecological roles. However, lichen diversity in many National Parks is poorly characterized. Because of this, limited interpretive resources are currently available. Here we report a preliminary checklist of the lichen species found in Great Basin...
Article
Processes that shape biogeographic patterns in lichens have been of long-standing interest, especially in extreme environments. Lecideoid lichens in Antarctica have been relatively well-studied and are thought to have a high degree of endemism. However, recent collection efforts in montane regions of western North America have uncovered lecideoid l...
Article
Twenty-five North American lichens are issued in this exsiccat series, numbers 151-175. In this fascicle, collections were made from nine states, including: Alaska (1), Arizona (3), California (2), Colorado (6), Idaho (1), Montana (4), Nevada (2), New Mexico (4), and Utah (2). Here, Thamnolia subuliformis (Ehrh.) W. L. Culb. (No. 173) is reported a...
Article
Full-text available
Historical mass extinction events had major impacts on biodiversity patterns. The most recent and intensively studied event is the Cretaceous – Paleogene (K-Pg) boundary (ca. 66 million years ago [MYA]). However, the factors that may have impacted diversification dynamics vary across lineages. We investigated the macroevolutionary dynamics with a s...
Article
Full-text available
Aim Contemporary species’ distributions are shaped by both geography and historical events, such as extinction, diversification in specific areas and long‐distance dispersals. In the most diverse family of lichen‐forming fungi, Parmeliaceae, the Hypogymnioid clade, is an example of an evolutionary lineage comprised of species occurring in temperate...
Article
Full-text available
Biological soil crusts (BSCs) exist commonly on soil surfaces in many arid and semiarid areas, and disturbed soil surfaces in more mesic environments. BSCs perform many essential ecological functions. Substantial resources have been invested trying to restore or replace BSCs that have been damaged by anthropogenic disturbances, with various levels...
Article
Full-text available
Fungal reproduction is regulated by the mating-type (MAT1) locus, which typically comprises two idiomorphic genes. The presence of one or both allelic variants at the locus determines the reproductive strategy in fungi-homothallism versus heterothallism. It has been hypothesized that self-fertility via homothallism is widespread in lichen-forming f...
Article
Comprehensive lichen inventories at biomonitoring reference sites provide valuable ecological information but are notoriously difficult to obtain. Due to the limited number of specialists and challenges with generating objective species inventories, investigating alternative or complementary strategies for compiling lichen inventories is paramount...
Article
Full-text available
Taxonomic ranks above the species level are inherently arbitrary. However, there is a growing number of publications aimed at more consistent classifications with comparable ranks among taxa. For this study, we use a recently developed temporal approach that utilizes time-calibrated chronograms to identify and define temporal bands for comparable o...
Article
Full-text available
Xanthoparmelia (Parmeliaceae, Ascomycota) is the most species-rich genus of lichen-forming fungi. Species boundaries are based on morphological and chemical features, varying reproductive strategies and, more recently, molecular sequence data. The isidiate Xanthoparmelia mexicana group is common in arid regions of North and Central America and incl...
Article
Phycologia: 2018, Vol. 57, No. 5, pp. 503-524. www.phycologia.org https://doi.org/10.2216/17-134.1 The class Trebouxiophyceae is comprised of coccoid to ellipsoid unicells, filaments, blades and colony-forming species of green algae occurring in diverse terrestrial and aquatic environments. Some representatives have evolved parasitic heterotrophic...
Article
A broad range of morphological variation is known to occur within the lichen-forming fungal genus Acarospora (Acarosporaceae, Ascomycota). In this study, we investigated the relationships of a number of interesting Acarospora collections from western North America using morphological, chemical and molecular sequence data. Our results revealed patte...
Article
Full-text available
Taxonomic ranks above the species level are inherently arbitrary. However, there is a growing number of publications aimed at more consistent classifications with comparable ranks among taxa. For this study, we use a recently developed temporal approach that utilizes time-calibrated chronograms to identify and define temporal bands for comparable o...
Article
Full-text available
Phylogenomic datasets continue to enhance our understanding of evolutionary relationships in many lineages of organisms. However, genome-scale data have not been widely implemented in reconstructing relationships in lichenized fungi. Here we generate a data set comprised of 2556 single-copy protein-coding genes to reconstruct previously unresolved...
Article
Full-text available
Species richness is not evenly distributed across the tree of life and a limited number of lineages comprise an extraordinarily large number of species. In lichen-forming fungi, only two genera are known to be ‘ultradiverse’ (>500 species), with the most diverse genus, Xanthoparmelia , consisting of c . 820 spe c ies. While Australia and South Afri...
Article
Full-text available
The effect of microevolutionary processes on macroevolutionary patterns, and vice versa, is an important but under-investigated question. Here we present an integrative population genetic and phylogenetic study using molecular sequence data from three lichen-forming fungal lineages to empirically test the potential correlation between effective pop...
Article
Full-text available
Multiple drivers shape the spatial distribution of species, including dispersal capacity, niche incumbency, climate variability, orographic barriers, and plate tectonics. However, biogeographic patterns of fungi commonly do not fit conventional expectations based on studies of animals and plants. Fungi, in general, are known to occur across exceedi...
Data
Niche ecospace as described by PC1 and PC2, derived from a phylogenetic PCA on the mean candidate species values for 19 bioclim variables. Candidate species are plotted by name, and eigenvectors as arrows. Together, PC1 (66.4%) and PC2 (20.2%) account for account for >86% of the variation. Temperature and precipitation variables are associated with...
Data
Bioclimatic data for 19 Bioclim variables for candidate species. Latitude and longitude were used to extract bioclimatic variables at a spatial resolution of 2.5 min, using the R (R Core Team, 2015) package raster (Hijmans et al., 2015).
Data
List of specimens included in this study.
Article
Full-text available
Lineages with broad, intercontinental distributions can provide insight into factors that influence diversity across both temporal and geographic scales. Lichens are well known for distinct biogeographic distribution patterns, including a high number of lineages with intercontinental distributions. The lichen-forming fungal genus Oropogon, from one...
Article
Full-text available
Biological soil crusts (BSCs) commonly occupy the surface of many arid and semiarid soils, and disturbed soils in more mesic environments. BSCs perform many essential ecological services. Substantial resources have been invested trying to restore BSCs that have been damaged by anthropogenic disturbances, largely to no avail. The nexus of science re...
Article
Full-text available
Despite increasing availability of phylogenomic datasets, strategies to generate genome-scale data from organisms involved in symbiotic relationships remains challenging. Re