Steve Stephenson
University of Arkansas, Biological Sciences, Faculty Member
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An analysis of ITS sequences of Didymium squamulosum, a myxomycete regarded as cosmopolitan, shows variation among geographically separated isolates. ITS 1 and 2 and 5.8S rDNA were amplified from specimens collected in widely scattered... more
An analysis of ITS sequences of Didymium squamulosum, a myxomycete regarded as cosmopolitan, shows variation among geographically separated isolates. ITS 1 and 2 and 5.8S rDNA were amplified from specimens collected in widely scattered localities. The sequences were analyzed by parsimony analysis and the resulting trees show separate, moderate and well supported clades grouping some, but not all, of the geographic locations. ITS is the first molecular marker examined for intraspecific variation in myxomycetes, and although sequence analysis shows statistically significant differences among sequences from the 14 specimens considered, the heterogeneity in ITS 1 and ITS 2 appears to be too great for any more meaningful biogeographical conclusions. Variation in the 5.8S and the amount of variation found in ITS 1 and 2 may signify that the isolates examined represent a complex of sibling species, although this particular marker cannot be used to make that distinction in this myxomycete.
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Research Interests: Earth Sciences, Environmental Science, Acid Mine Drainage, Trace Metals, Environmental Chemistry, and 15 moreBiological Sciences, Aquatic Ecosystem, Environmental Sciences, Coal Mining, Surface Water, Environmental Effect, Transect, Species Diversity, Species Composition, Environmental quality, Streams, Toxic Metals, Stratified Random Sampling, Bryophyte, and Environment Quality
Summary In mountainous regions, road construction is accompanied by large‐scale physical disturbance associated with cut and fill operations that drastically alter the landscape. Cut operations remove soil and rock from the hillside above... more
Summary In mountainous regions, road construction is accompanied by large‐scale physical disturbance associated with cut and fill operations that drastically alter the landscape. Cut operations remove soil and rock from the hillside above the proposed road, while soil and rock are deposited on the down‐slope area in fill operations. The resultant roadsides are highly disturbed habitats characterized by plant communities maintained at an early successional stage. They are often planted with non‐native species and frequently provide vectors for the introduction and spread of invasive species. Public transportation managers need to balance the rapid revegetation of roadsides with the goal of maximizing use of native species and minimizing the introduction of non‐native species. This study examined vegetation–site relationships along 13 major four‐lane highways in West Virginia, USA, using analysis of variance, multiresponse permutation procedures and indicator species analysis. Mean so...
Research Interests: Management, Geography, Exotic Species, Ecology, Invasive Species, and 15 moreApplied Ecology, Habitat, Applied, Indicator species, Erosion Control, Introduced species, Analysis of Variance, Plant Community, Large Scale, Ecological Applications, Non native Species, Community Composition, Native Species, ENVIRONMENTAL SCIENCE AND MANAGEMENT, and Plant species richness
Abstract This study represented an effort to apply some of the relatively well-known biogeographical and macroecological models to the observed structure of myxomycete assemblages, with emphasis on the northern Neotropical region. A... more
Abstract This study represented an effort to apply some of the relatively well-known biogeographical and macroecological models to the observed structure of myxomycete assemblages, with emphasis on the northern Neotropical region. A series of 28 ...
Research Interests: Community Ecology, Biology, Ecology, Thailand, Costa Rica, and 15 moreBiogeography, Mexico, Biological Sciences, Environmental Sciences, Guatemala, Fungal ecology, Central America, Niche Breadth, Neotropical Region, Latitudinal Gradient, MEXICO, Niche, Temperate Climate, Temperate Forest, and myxogastrids
ABSTRACT The distribution of fruit bodies of myxomycetes under different ecological conditions at the Los Amigos Biological Station in southeastern Peru was studied. Six study areas were surveyed using a combined field-laboratory... more
ABSTRACT The distribution of fruit bodies of myxomycetes under different ecological conditions at the Los Amigos Biological Station in southeastern Peru was studied. Six study areas were surveyed using a combined field-laboratory methodology under different climatic conditions. Sixty species were recorded and differences in fruit body abundance and structure of the assemblages were found among collecting periods. A diversity analysis based on fruit bodies showed that values were predominantly higher during the dry period. An analysis of microenvironmental conditions applied to a subset of data collected in the field showed that pH and substratum diameter accounted for most of the variation. In addition, the most abundant myxomycetes based on fruit body occurrence showed a multivariate arrangement that suggests the existence of functional groups.
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Patterns of occurrence of myxomycetes on different types of lianas were assessed at the Mushroom Research Centre in northern Thailand during the rainy season of Jun.Sep. 2008. A total of 30 species representing, 15 genera of myxomycetes,... more
Patterns of occurrence of myxomycetes on different types of lianas were assessed at the Mushroom Research Centre in northern Thailand during the rainy season of Jun.Sep. 2008. A total of 30 species representing, 15 genera of myxomycetes, were obtained from a series of moist ...
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Research Interests: Biology, Ecology, Biodiversity, Biological Sciences, Environmental Sciences, and 11 moreSlime Molds, Fungal ecology, Species Distribution, Litter, Plant Litter, Environmental Gradient, National Park, Canonical Correspondence Analysis, Elevated Temperature, Elevation Gradient, and species abundance distribution
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ABSTRACT Data were obtained on the assemblages of corticolous myxomycetes (plasmodial slime moulds or myxogastrids) associated with the bark surface of living white oak (Quercus alba) trees from two different size classes. Bark samples... more
ABSTRACT Data were obtained on the assemblages of corticolous myxomycetes (plasmodial slime moulds or myxogastrids) associated with the bark surface of living white oak (Quercus alba) trees from two different size classes. Bark samples obtained from larger trees were characterized by higher values for both species richness and diversity when compared to those collected from smaller trees. This might have been expected since the former possess a larger surface area and presumably have persisted over a longer period of time. However, the myxomycete assemblage associated with smaller trees was appreciably different and did not simply represent a depauperate version of the assemblage associated with larger trees. This suggests that the differences observed between size classes cannot be simply attributed to size alone.
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Successful penetration of living plant tissue by fungal pathogens is preceded by an exchange of signals between both organisms. Recent mutational approaches revealed the importance of cAMP-dependent signalling pathways for fungal... more
Successful penetration of living plant tissue by fungal pathogens is preceded by an exchange of signals between both organisms. Recent mutational approaches revealed the importance of cAMP-dependent signalling pathways for fungal development and virulence on their hosts.
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Specimens of myxomycetes obtained as field collections or from moist chamber cultures during biodiversity surveys carried out in several regions of Australia during the period of 2004 to 2008 have included 12 species not previously known... more
Specimens of myxomycetes obtained as field collections or from moist chamber cultures during biodiversity surveys carried out in several regions of Australia during the period of 2004 to 2008 have included 12 species not previously known from the country ...
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Myxomycetes (plasmodial slime moulds) are best known from temperate and boreal forests, where they are commonly found in association with decaying coarse woody debris and leaf litter on the forest floor (Martin & Alexopoulos 1969). There... more
Myxomycetes (plasmodial slime moulds) are best known from temperate and boreal forests, where they are commonly found in association with decaying coarse woody debris and leaf litter on the forest floor (Martin & Alexopoulos 1969). There have been only a few reports of myxomycetes from either the continent of Antarctica or the subantarctic islands. In what apparently represents the first record of a myxomycete from the south polar region, Horak (1966) described a new species, Diderma antarcticolum Horak, from material collected on the Antarctic Peninsula (64°53′S, 62°53′W). Later, Ing & Smith (1980,1983) reported Didymium dubium Rost., Lamproderma arcyrioides (Sommerf.) Rost., Stemonitopsis (Comatricha) subcaespitosa (Peck) Nann.- Brem. and Diderma niveum (Rost.) Macbr. from South Georgia (54–55°S, 36–38°W). They also indicated that the latter species was known from Signy Island, South Orkney Islands (60°43′S, 45°36′W) and the Antarctic Peninsula (65°16′S, 64°08′W) as well as South ...
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The results of a biodiversity survey for myxomycetes, carried out in montane rainforests of the Ecological Reserve “Alturas de Banao” in the Macizo Guamuahaya Mountains of central Cuba, are reported here. The survey yielded more than 200... more
The results of a biodiversity survey for myxomycetes, carried out in montane rainforests of the Ecological Reserve “Alturas de Banao” in the Macizo Guamuahaya Mountains of central Cuba, are reported here. The survey yielded more than 200 field collections of myxomycetes, and 56 species were identified, from these field collections and moist chamber culture collections. Amongst these were 23 species recorded for the first time from Cuba: Arcyria afroalpina, A. globosa, Badhamia melanospora, Ceratiomyxa sphaerosperma, Clastoderma debaryanum, Collaria lurida, Comatricha laxa, C. nigra, C. tenerrima, Craterium concinnum, Cribraria microcarpa, C. tenella, Diderma corrugatum, Didymium iridis, Echinostelium bisporum, E. minutum, Hemitrichia pardina, Licea bulbosa, L. erecta var. erectoides, L. scyphoides, Perichaena vermicularis, Physarum crateriforme, and P. galbeum, Dead leaves of the palm Roystonea regia were an especially productive substrate for myxomycetes, with members of the Trichi...
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Research Interests: Geography, Forestry, Plant Biology, Biology, Ecological Succession, and 3 moreCastanea, Basal Area, and Balsam
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The present study represented an effort to develop a better understanding of the assemblages of myxomycetes fruiting under natural conditions in the field during two different seasons in the tropical forests of Chiang Mai Province,... more
The present study represented an effort to develop a better understanding of the assemblages of myxomycetes fruiting under natural conditions in the field during two different seasons in the tropical forests of Chiang Mai Province, northern Thailand. Sixty-seven ...
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Research Interests: Geography, Plant Biology, Biology, Ecology, Biodiversity, and 3 morePatagonia, Tierra, and Tierra del Fuego
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Twelve new records of myxomycetes are reported for Colombia. These additions increase the number of myxomycetes known from this country to 108 species. Since the Colombian territory is part of a biodiversity-rich region in the heart of... more
Twelve new records of myxomycetes are reported for Colombia. These additions increase the number of myxomycetes known from this country to 108 species. Since the Colombian territory is part of a biodiversity-rich region in the heart of the Neotropics, the present effort may be considered as a minor contribution. However, due to scarcity of myxomycete research in this country and the importance of inventories involving microorganisms for such purposes as restoration ecology and ecosystem functioning projects, the data presented herein represent a necessary contribution to an understudied aspect of tropical ecology.
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The first checklist of the myxomycetes (plasmodial slime molds) of the Big Thicket National Preserve is presented herein. Eighty-eight spe-cies are listed. Fifty-three of the species listed are new records for the Preserve of which six... more
The first checklist of the myxomycetes (plasmodial slime molds) of the Big Thicket National Preserve is presented herein. Eighty-eight spe-cies are listed. Fifty-three of the species listed are new records for the Preserve of which six are new records for Texas. One of the species new to Texas and the Preserve (Arcyria margino-undulata) is considered to be rare. Three other species (Craterium paraguayense, Physarella ob-longa, and Physarum bogoriense) are recorded more often from subtropical and tropical than temperate habitats. RESUMEN Se presenta el primer catálogo de myxomycetes de la Big Thicket National Preserve. Se listan ochenta y ocho especies. Cincuenta y tres de las especies listadas son citas nuevas para la Reserva y de ellas seis son citas nuevas para Texas. Una de las especies nueva para Texas y la Reserva (Arcyria margino-undulata) se considera rara. Otras tres especies (Craterium paraguayense, Physarella oblonga, y Physarum bo-goriense) se colectan más a menudo en háb...