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1.
Proc Natl Acad Sci U S A ; 117(21): 11551-11558, 2020 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-32404424

RESUMEN

As the primary decomposers of organic material in terrestrial ecosystems, fungi are critical agents of the global carbon cycle. Yet our ability to link fungal community composition to ecosystem functioning is constrained by a limited understanding of the factors accounting for different wood decomposition rates among fungi. Here we examine which traits best explain fungal decomposition ability by combining detailed trait-based assays on 34 saprotrophic fungi from across North America in the laboratory with a 5-y field study comprising 1,582 fungi isolated from 74 decomposing logs. Fungal growth rate (hyphal extension rate) was the strongest single predictor of fungal-mediated wood decomposition rate under laboratory conditions, and accounted for up to 27% of the in situ variation in decomposition in the field. At the individual level, decomposition rate was negatively correlated with moisture niche width (an indicator of drought stress tolerance) and with the production of nutrient-mineralizing extracellular enzymes. Together, these results suggest that decomposition rates strongly align with a dominance-tolerance life-history trade-off that was previously identified in these isolates, forming a spectrum from slow-growing, stress-tolerant fungi that are poor decomposers to fast-growing, highly competitive fungi with fast decomposition rates. Our study illustrates how an understanding of fungal trait variation could improve our predictive ability of the early and midstages of wood decay, to which our findings are most applicable. By mapping our results onto the biogeographic distribution of the dominance-tolerance trade-off across North America, we approximate broad-scale patterns in intrinsic fungal-mediated wood decomposition rates.


Asunto(s)
Hongos/fisiología , Madera/microbiología , Ciclo del Carbono/fisiología , Ecosistema , Hongos/clasificación , Hongos/enzimología , Hifa/fisiología , Micobioma/fisiología , América del Norte
2.
Mol Ecol ; 30(3): 855-873, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33301628

RESUMEN

Although most predators are generalists, the majority of studies on the association between prey availability and prey consumption have focused on specialist predators. To investigate the role of highly generalist predators in a complex food web, we measured the relationships between prey consumption and prey availability in two common arthropodivorous bats. Specifically, we used high-throughput amplicon sequencing coupled with a known mock community to characterize seasonal changes in little brown and big brown bat diets. We then linked spatiotemporal variation in prey consumption with quantitative prey availability estimated from intensive prey community sampling. We found that although quantitative prey availability fluctuated substantially over space and time, the most commonly consumed prey items were consistently detected in bat diets independently of their respective abundance. Positive relationships between prey abundance and probability of consumption were found only among prey groups that were less frequently detected in bat diets. While the probability of prey consumption was largely unrelated to abundance, the community structure of prey detected in bat diets was influenced by the local or regional abundance of prey. Observed patterns suggest that while little brown and big brown bats maintain preferences for particular prey independently of quantitative prey availability, total dietary composition may reflect some degree of opportunistic foraging. Overall, our findings suggest that generalist predators can display strong prey preferences that persist despite quantitative changes in prey availability.


Asunto(s)
Quirópteros , Animales , Dieta , Cadena Alimentaria , Secuenciación de Nucleótidos de Alto Rendimiento , Conducta Predatoria
3.
J Ind Microbiol Biotechnol ; 48(9-10)2021 Dec 23.
Artículo en Inglés | MEDLINE | ID: mdl-34415047

RESUMEN

Many fungi develop both asexual and sexual spores that serve as propagules for dissemination and/or recombination of genetic traits. Asexual spores are often heavily pigmented and this pigmentation provides protection from UV light. However, little is known about any purpose pigmentation that may serve for sexual spores. The model Ascomycete Aspergillus nidulans produces both green pigmented asexual spores (conidia) and red pigmented sexual spores (ascospores). Here we find that the previously characterized red pigment, asperthecin, is the A. nidulans ascospore pigment. The asperthecin biosynthetic gene cluster is composed of three genes: aptA, aptB, and aptC, where deletion of either aptA (encoding a polyketide synthase) or aptB (encoding a thioesterase) yields small, mishappen hyaline ascospores; while deletion of aptC (encoding a monooxygenase) yields morphologically normal but purple ascospores. ∆aptA and ∆aptB but not ∆aptC or wild type ascospores are extremely sensitive to UV light. We find that two historical ascospore color mutants, clA6 and clB1, possess mutations in aptA and aptB sequences, respectively.


Asunto(s)
Aspergillus nidulans , Antraquinonas , Aspergillus nidulans/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulación Fúngica de la Expresión Génica , Pigmentación , Esporas Fúngicas/genética , Esporas Fúngicas/metabolismo , Rayos Ultravioleta
4.
Mol Ecol ; 28(22): 4971-4986, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31596982

RESUMEN

A prevailing paradigm in forest ecology is that wood-boring beetles facilitate wood decay and carbon cycling, but empirical tests have yielded mixed results. We experimentally determined the effects of wood borers on fungal community assembly and wood decay within pine trunks in the southeastern United States. Pine trunks were made either beetle-accessible or inaccessible. Fungal communities were compared using culturing and high-throughput amplicon sequencing (HTAS) of DNA and RNA. Prior to beetle infestation, living pines had diverse fungal endophyte communities. Endophytes were displaced by beetle-associated fungi in beetle-accessible trees, whereas some endophytes persisted as saprotrophs in beetle-excluded trees. Beetles increased fungal diversity several fold. Over forty taxa of Ascomycota were significantly associated with beetles, but beetles were not consistently associated with any known wood-decaying fungi. Instead, increasing ambrosia beetle infestations caused reduced decay, consistent with previous in vitro experiments that showed beetle-associated fungi reduce decay rates by competing with decay fungi. No effect of bark-inhabiting beetles on decay was detected. Platypodines carried significantly more fungal taxa than scolytines. Molecular results were validated by synthetic and biological mock communities and were consistent across methodologies. RNA sequencing confirmed that beetle-associated fungi were biologically active in the wood. Metabarcode sequencing of the LSU/28S marker recovered important fungal symbionts that were missed by ITS2, though community-level effects were similar between markers. In contrast to the current paradigm, our results indicate ambrosia beetles introduce diverse fungal communities that do not extensively decay wood, but instead reduce decay rates by competing with wood decay fungi.


Asunto(s)
Escarabajos/genética , Hongos/genética , Simbiosis/genética , Gorgojos/genética , Madera/genética , Animales , Ascomicetos/genética , Biomasa , ADN/genética , Ecología/métodos , Bosques , Micobioma/genética , Pinus/genética , ARN/genética , Sudeste de Estados Unidos , Árboles/genética
5.
Biol Chem ; 399(12): 1375-1388, 2018 11 27.
Artículo en Inglés | MEDLINE | ID: mdl-30367778

RESUMEN

Pseudogymnoascus destructans is a pathogenic fungus responsible for White-nose Syndrome (WNS), a disease afflicting multiple species of North American bats. Pseudogymnoascus destructans infects susceptible bats during hibernation, invading dermal tissue and causing extensive tissue damage. In contrast, other Pseudogymnoascus species are non-pathogenic and cross-species comparisons may therefore reveal factors that contribute to virulence. In this study, we compared the secretome of P. destructans with that from several closely related Pseudogymnoascus species. A diverse set of hydrolytic enzymes were identified, including a putative serine peptidase, PdCP1, that was unique to the P. destructans secretome. A recombinant form of PdCP1 was purified and substrate preference determined using a multiplexed-substrate profiling method based on enzymatic degradation of a synthetic peptide library and analysis by mass spectrometry. Most peptide substrates were sequentially truncated from the carboxyl-terminus revealing that this enzyme is a bona fide carboxypeptidase. Peptides with arginine located close to the carboxyl-terminus were rapidly cleaved, and a fluorescent substrate containing arginine was therefore used to characterize PdCP1 activity and to screen a selection of peptidase inhibitors. Antipain and leupeptin were found to be the most potent inhibitors of PdCP1 activity.


Asunto(s)
Ascomicetos/enzimología , Carboxipeptidasas/metabolismo , Quirópteros/microbiología , Micosis/metabolismo , Animales , Antipaína/farmacología , Carboxipeptidasas/antagonistas & inhibidores , Carboxipeptidasas/aislamiento & purificación , Leupeptinas/farmacología , Micosis/microbiología , Síndrome
6.
Microb Ecol ; 76(3): 839-850, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29476344

RESUMEN

Separating symbioses from incidental associations is a major obstacle in symbiosis research. In this survey of fungi associated with Asian bark and ambrosia beetles, we used quantitative culture and DNA barcode identification to characterize fungal communities associated with co-infesting beetle species in pines (Pinus) of China and Vietnam. To quantitatively discern likely symbioses from coincidental associations, we used multivariate analysis and multilevel pattern analysis (a type of indicator species analysis). Nearly half of the variation in fungal community composition in beetle galleries and on beetle bodies was explained by beetle species. We inferred a spectrum of ecological strategies among beetle-associated fungi: from generalist multispecies associates to highly specialized single-host symbionts that were consistently dominant within the mycangia of their hosts. Statistically significant fungal associates of ambrosia beetles were typically only found with one beetle species. In contrast, bark beetle-associated fungi were often associated with multiple beetle species. Ambrosia beetles and their galleries were frequently colonized by low-prevalence ambrosia fungi, suggesting that facultative ambrosial associations are commonplace, and ecological mechanisms such as specialization and competition may be important in these dynamic associations. The approach used here could effectively delimit symbiotic interactions in any system where symbioses are obscured by frequent incidental associations. It has multiple advantages including (1) powerful statistical tests for non-random associations among potential symbionts, (2) simultaneous evaluation of multiple co-occurring host and symbiont associations, and (3) identifying symbionts that are significantly associated with multiple host species.


Asunto(s)
Escarabajos/microbiología , Hongos/aislamiento & purificación , Pinus/parasitología , Simbiosis , Animales , Biodiversidad , China , Escarabajos/clasificación , Escarabajos/fisiología , Hongos/clasificación , Hongos/genética , Hongos/fisiología , Especificidad del Huésped , Filogenia , Vietnam
7.
Proc Biol Sci ; 283(1827): 20160106, 2016 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-27009222

RESUMEN

Primary cavity excavators, such as woodpeckers, are ecosystem engineers in many systems. Associations between cavity excavators and fungi have long been hypothesized to facilitate cavity excavation, but these relationships have not been experimentally verified. Fungi may help excavators by softening wood, while excavators may facilitate fungal dispersal. Here we demonstrate that excavators facilitate fungal dispersal and thus we report the first experimental evidence of a symbiosis between fungi and a cavity excavator, the red-cockaded woodpecker (RCW,Picoides borealis). Swab samples of birds showed that RCWs carry fungal communities similar to those found in their completed excavations. A 26-month field experiment using human-made aseptically drilled excavations in live trees, half of which were inaccessible to RCWs, demonstrated that RCWs directly alter fungal colonization and community composition. Experimental excavations that were accessible to RCWs contained fungal communities similar to natural RCW excavations, whereas inaccessible experimental excavations contained significantly different fungal communities. Our work demonstrates a complex symbiosis between cavity excavators and communities of fungi, with implications for forest ecology, wildlife management, and conservation.


Asunto(s)
Basidiomycota/fisiología , Aves/microbiología , Pinus/microbiología , Simbiosis , Animales , Basidiomycota/clasificación , ADN de Hongos/genética , Comportamiento de Nidificación , North Carolina , Análisis de Secuencia de ADN/veterinaria
8.
Appl Environ Microbiol ; 80(5): 1726-31, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24375140

RESUMEN

White-nose syndrome is a fungal disease that has decimated bat populations across eastern North America. Identification of the etiologic agent, Pseudogymnoascus destructans (formerly Geomyces destructans), in environmental samples is essential to proposed management plans. A major challenge is the presence of closely related species, which are ubiquitous in many soils and cave sediments and often present in high abundance. We present a dual-probe real-time quantitative PCR assay capable of detecting and differentiating P. destructans from closely related fungi in environmental samples from North America. The assay, based on a single nucleotide polymorphism (SNP) specific to P. destructans, is capable of rapid low-level detection from various sampling media, including sediment, fecal samples, wing biopsy specimens, and skin swabs. This method is a highly sensitive, high-throughput method for identifying P. destructans, other Pseudogymnoascus spp., and Geomyces spp. in the environment, providing a fundamental component of research and risk assessment for addressing this disease, as well as other ecological and mycological work on related fungi.


Asunto(s)
Ascomicetos/clasificación , Ascomicetos/aislamiento & purificación , Microbiología Ambiental , Micología/métodos , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Ascomicetos/genética , ADN de Hongos/genética , América del Norte , Sondas de Oligonucleótidos/genética , Polimorfismo de Nucleótido Simple , Sensibilidad y Especificidad
9.
Appl Environ Microbiol ; 79(4): 1293-301, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23241985

RESUMEN

White-nose syndrome (WNS) is an emerging disease of hibernating bats caused by the recently described fungus Geomyces destructans. First isolated in 2008, the origins of this fungus in North America and its ability to persist in the environment remain undefined. To investigate the correlation between manifestation of WNS and distribution of G. destructans in the United States, we analyzed sediment samples collected from 55 bat hibernacula (caves and mines) both within and outside the known range of WNS using a newly developed real-time PCR assay. Geomyces destructans was detected in 17 of 21 sites within the known range of WNS at the time when the samples were collected; the fungus was not found in 28 sites beyond the known range of the disease at the time when environmental samples were collected. These data indicate that the distribution of G. destructans is correlated with disease in hibernating bats and support the hypothesis that the fungus is likely an exotic species in North America. Additionally, we examined whether G. destructans persists in infested bat hibernacula when bats are absent. Sediment samples were collected from 14 WNS-positive hibernacula, and the samples were screened for viable fungus by using a culture technique. Viable G. destructans was cultivated from 7 of the 14 sites sampled during late summer, when bats were no longer in hibernation, suggesting that the fungus can persist in the environment in the absence of bat hosts for long periods of time.


Asunto(s)
Ascomicetos/aislamiento & purificación , Quirópteros/microbiología , Micosis/veterinaria , Animales , Ascomicetos/patogenicidad , ADN de Hongos/genética , ADN de Hongos/aislamiento & purificación , Microbiología Ambiental , Micosis/epidemiología , Micosis/microbiología , Reacción en Cadena en Tiempo Real de la Polimerasa , Topografía Médica , Estados Unidos/epidemiología
10.
Mycologia ; 105(6): 1391-411, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23935025

RESUMEN

Phylogenetic relationships among members of the antrodia clade were investigated with molecular data from two nuclear ribosomal DNA regions, LSU and ITS. A total of 123 species representing 26 genera producing a brown rot were included in the present study. Three DNA datasets (combined LSU-ITS dataset, LSU dataset, ITS dataset) comprising sequences of 449 isolates were evaluated with three different phylogenetic analyses (maximum likelihood, maximum parsimony, Bayesian inference). We present a phylogenetic overview of the five main groups recovered: the fibroporia, laetiporus, postia, laricifomes and core antrodia groups. Not all of the main groups received strong support in the analyses, requiring further research. We were able to identify a number of well supported clades within the main groups.


Asunto(s)
ADN Espaciador Ribosómico/genética , Filogenia , Polyporales/clasificación , ADN de Hongos/genética , Datos de Secuencia Molecular , Polyporales/genética
11.
Mycologia ; 105(2): 253-9, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-22962349

RESUMEN

The fungus Geomyces destructans is the causative agent of white-nose syndrome (WNS), a disease that has killed millions of North American hibernating bats. We describe a real-time TaqMan PCR test that detects DNA from G. destructans by targeting a portion of the multicopy intergenic spacer region of the rRNA gene complex. The test is highly sensitive, consistently detecting as little as 3.3 fg genomic DNA from G. destructans. The real-time PCR test specifically amplified genomic DNA from G. destructans but did not amplify target sequence from 54 closely related fungal isolates (including 43 Geomyces spp. isolates) associated with bats. The test was qualified further by analyzing DNA extracted from 91 bat wing skin samples, and PCR results matched histopathology findings. These data indicate the real-time TaqMan PCR method described herein is a sensitive, specific and rapid test to detect DNA from G. destructans and provides a valuable tool for WNS diagnostics and research.


Asunto(s)
Ascomicetos/aislamiento & purificación , Quirópteros/microbiología , Micosis/veterinaria , Reacción en Cadena en Tiempo Real de la Polimerasa/veterinaria , Animales , Ascomicetos/clasificación , Ascomicetos/genética , ADN de Hongos/química , ADN de Hongos/genética , ADN Intergénico , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Micosis/diagnóstico , Micosis/microbiología , Filogenia , Sensibilidad y Especificidad , Piel/microbiología , Especificidad de la Especie , Factores de Tiempo , Estados Unidos
12.
Mycologia ; 105(2): 237-52, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23074174

RESUMEN

The recent emergence of white-nose syndrome (WNS), a fungal disease causing unprecedented mortality among hibernating bats of eastern North America, has revealed a knowledge gap regarding fungal communities associated with bats and their hibernacula. We used culture-based techniques to investigate the diversity of fungi in soil samples collected from 24 bat hibernacula in the eastern United States. Ribosomal RNA regions (internal transcribed spacer and partial intergenic spacer) were sequenced to preliminarily characterize isolates. Geomyces species were one of the most abundant and diverse groups cultured, representing approximately 33% of all isolates. Geomyces destructans was isolated from soil samples from three hibernacula in states where WNS is known to occur, and many of the other cultured Geomyces isolates likely represent undescribed taxa. Further characterization of the diversity of fungi that occur in hibernacula both will facilitate an improved understanding of the ecology of G. destructans within this complex fungal community and provide an opportunity to identify characteristics that differentiate G. destructans from non-pathogenic relatives.


Asunto(s)
Quirópteros/microbiología , Hongos/aislamiento & purificación , Micosis/veterinaria , Microbiología del Suelo , Animales , Ascomicetos/clasificación , Ascomicetos/genética , Ascomicetos/aislamiento & purificación , Secuencia de Bases , Basidiomycota/clasificación , Basidiomycota/genética , Basidiomycota/aislamiento & purificación , Quirópteros/fisiología , ADN de Hongos/química , ADN de Hongos/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Hongos/clasificación , Hongos/genética , Hibernación , Datos de Secuencia Molecular , Micosis/microbiología , Filogenia , Análisis de Secuencia de ADN/veterinaria , Estados Unidos
13.
Mycologia ; 115(1): 107-121, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36533930

RESUMEN

The fungus currently known as Laetiporus persicinus is a recognizable brown-rot decayer that is widespread on oak hosts in the southeastern United States. This species was first described as Polyporus persicinus in 1872 based on collections by Henry W. Ravenel from South Carolina. In this study, we elucidate the phylogenetic relationships of Laetiporus persicinus based on maximum likelihood and Bayesian inference analyses of a four-locus data set (18S, 28S, rpb2, and tef1) from taxa within the Fomitopsidaceae and Laetiporaceae. The internal transcribed spacer (ITS) region was analyzed separately because it was not possible to align this locus across a diverse data set that included taxa from multiple families. Our analysis and previous studies indicate that Laetiporus persicinus does not belong to Laetiporus sensu stricto, and we found a strongly supported relationship between Laetiporus persicinus and the African species Kusaghiporia usambarensis, despite the fact that the 28S phylogeny resolved a different (but unsupported) topology. Here, we propose Kusaghiporia persicinus, comb. nov., based on a combination of morphological and molecular data. Laetiporus persicinus shares many morphological features with K. usambarensis that are missing in other Laetiporus species, including centrally stipitate basidiomata, a brown to pinkish pileus surface, and a pore layer that bruises when touched. However, K. usambarensis and L. persicinus differ in basidiospore size and shape as well as their geographic distributions. We provide a revised taxonomic treatment for this common wood-decay fungus.


Asunto(s)
Basidiomycota , Humanos , Filogenia , Teorema de Bayes , Basidiomycota/genética , Esporas Fúngicas/genética
14.
Genome Biol Evol ; 15(8)2023 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-37498334

RESUMEN

To elucidate the genomic traits of ecological diversification in the Hymenochaetales, we sequenced 15 new genomes, with attention to ectomycorrhizal (EcM) Coltricia species. Together with published data, 32 genomes, including 31 Hymenochaetales and one outgroup, were comparatively analyzed in total. Compared with those of parasitic and saprophytic members, EcM species have significantly reduced number of plant cell wall degrading enzyme genes, and expanded transposable elements, genome sizes, small secreted proteins, and secreted proteases. EcM species still retain some of secreted carbohydrate-active enzymes (CAZymes) and have lost the key secreted CAZymes to degrade lignin and cellulose, while possess a strong capacity to degrade a microbial cell wall containing chitin and peptidoglycan. There were no significant differences in secreted CAZymes between fungi growing on gymnosperms and angiosperms, suggesting that the secreted CAZymes in the Hymenochaetales evolved before differentiation of host trees into gymnosperms and angiosperms. Nevertheless, parasitic and saprophytic species of the Hymenochaetales are very similar in many genome features, which reflect their close phylogenetic relationships both being white rot fungi. Phylogenomic and molecular clock analyses showed that the EcM genus Coltricia formed a clade located at the base of the Hymenochaetaceae and divergence time later than saprophytic species. And Coltricia remains one to two genes of AA2 family. These indicate that the ancestors of Coltricia appear to have originated from saprophytic ancestor with the ability to cause a white rot. This study provides new genomic data for EcM species and insights into the ecological diversification within the Hymenochaetales based on comparative genomics and phylogenomics analyses.


Asunto(s)
Basidiomycota , Micorrizas , Filogenia , Genómica , Lignina/metabolismo
15.
Mycologia ; 104(5): 1200-5, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22505437

RESUMEN

Armillaria altimontana, previously considered North American biological species (NABS) X, is described as new. To date, it appears that A. altimontana prefers higher-elevation, mesic sites within the dry, conifer forest zone of western interior North America. This species has been found on hardwoods and conifers and is associated most commonly with Abies-dominated forest types in southern British Columbia, Washington, Oregon, Idaho and northern California. Partial elongation factor 1-alpha (tef1) sequences were generated from six isolates of A. altimontana originating from three locations in northern Idaho. Phylogenetic analyses of all 10 North American Armillaria species were carried out with maximum parsimony and maximum likelihood. Results indicate that isolates of A. altimontana formed a monophyletic group and clustered with A. calvescens, A. cepistipes, A. gallica and A. nabsnona, which is in agreement with recent phylogenetic studies of Armillaria.


Asunto(s)
Armillaria/clasificación , Armillaria/genética , Armillaria/aislamiento & purificación , Armillaria/ultraestructura , ADN de Hongos/genética , América del Norte , Factor 1 de Elongación Peptídica/genética , Filogenia , Análisis de Secuencia de ADN/métodos , Árboles/microbiología
16.
Ecol Evol ; 12(6): e8978, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35784069

RESUMEN

The extent to which persisting species may fill the functional role of extirpated or declining species has profound implications for the structure of biological communities and ecosystem functioning. In North America, arthropodivorous bats are threatened on a continent-wide scale by the spread of white-nose syndrome (WNS), a disease caused by the fungus Pseudogymnoascus destructans. We tested whether bat species that display lower mortality from this disease can partially fill the functional role of other bat species experiencing population declines. Specifically, we performed high-throughput amplicon sequencing of guano from two generalist predators: the little brown bat (Myotis lucifugus) and big brown bat (Eptesicus fuscus). We then compared changes in prey consumption before versus after population declines related to WNS. Dietary niches contracted for both species after large and abrupt declines in little brown bats and smaller declines in big brown bats, but interspecific dietary overlap did not change. Furthermore, the incidence and taxonomic richness of agricultural pest taxa detected in diet samples decreased following bat population declines. Our results suggest that persisting generalist predators do not necessarily expand their dietary niches following population declines in other predators, providing further evidence that the functional roles of different generalist predators are ecologically distinct.

17.
Mycologia ; 103(4): 731-40, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21289107

RESUMEN

Regions of rDNA are commonly used to infer phylogenetic relationships among fungal species and as DNA barcodes for identification. These regions occur in large tandem arrays, and concerted evolution is believed to reduce intragenomic variation among copies within these arrays, although some variation still might exist. Phylogenetic studies typically use consensus sequencing, which effectively conceals most intragenomic variation, but cloned sequences containing intragenomic variation are becoming prevalent in DNA databases. To understand effects of using cloned rDNA sequences in phylogenetic analyses we amplified and cloned the ITS region from pure cultures of six Laetiporus species and one Wolfiporia species (Basidiomycota, Polyporales). An average of 66 clones were selected randomly and sequenced from 21 cultures, producing a total of 1399 interpretable sequences. Significant variation (≥ 5% variation in sequence similarity) was observed among ITS copies within six cultures from three species clades (L. cincinnatus, L. sp. clade J, and Wolfiporia dilatohypha) and phylogenetic analyses with the cloned sequences produced different trees relative to analyses with consensus sequences. Cloned sequences from L. cincinnatus fell into more than one species clade and numerous cloned L. cincinnatus sequences fell into entirely new clades, which if analyzed on their own most likely would be recognized as "undescribed" or "novel" taxa. The use of a 95% cut off for defining operational taxonomic units (OTUs) produced seven Laetiporus OTUs with consensus ITS sequences and 20 OTUs with cloned ITS sequences. The use of cloned rDNA sequences might be problematic in fungal phylogenetic analyses, as well as in fungal bar-coding initiatives and efforts to detect fungal pathogens in environmental samples.


Asunto(s)
ADN de Hongos/genética , ADN Espaciador Ribosómico/genética , Polyporales/genética , Secuencia de Bases , Evolución Molecular , Variación Genética , Repeticiones de Microsatélite , Filogenia , Polyporales/clasificación , Análisis de Secuencia de ADN
18.
Mycologia ; 103(2): 241-6, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-20952799

RESUMEN

White-nose syndrome (WNS) is an emerging disease causing unprecedented morbidity and mortality among bats in eastern North America. The disease is characterized by cutaneous infection of hibernating bats by the psychrophilic fungus Geomyces destructans. Detection of G. destructans in environments occupied by bats will be critical for WNS surveillance, management and characterization of the fungal lifecycle. We initiated an rRNA gene region-based molecular survey to characterize the distribution of G. destructans in soil samples collected from bat hibernacula in the eastern United States with an existing PCR test. Although this test did not specifically detect G. destructans in soil samples based on a presence/absence metric, it did favor amplification of DNA from putative Geomyces species. Cloning and sequencing of PCR products amplified from 24 soil samples revealed 74 unique sequence variants representing 12 clades. Clones with exact sequence matches to G. destructans were identified in three of 19 soil samples from hibernacula in states where WNS is known to occur. Geomyces destructans was not identified in an additional five samples collected outside the region where WNS has been documented. This study highlights the diversity of putative Geomyces spp. in soil from bat hibernacula and indicates that further research is needed to better define the taxonomy of this genus and to develop enhanced diagnostic tests for rapid and specific detection of G. destructans in environmental samples.


Asunto(s)
Ascomicetos/clasificación , Ascomicetos/aislamiento & purificación , Quirópteros/microbiología , ADN de Hongos/genética , Micosis/veterinaria , Microbiología del Suelo , Animales , Ascomicetos/genética , Quirópteros/fisiología , Hibernación , Datos de Secuencia Molecular , Micosis/microbiología , Filogenia , Estados Unidos
19.
PLoS One ; 16(6): e0251893, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34086700

RESUMEN

Coarse woody debris (CWD) is an important component in forests, hosting a variety of organisms that have critical roles in nutrient cycling and carbon (C) storage. We developed a process-based model using literature, field observations, and expert knowledge to assess woody debris decomposition in forests and the movement of wood C into the soil and atmosphere. The sensitivity analysis was conducted against the primary ecological drivers (wood properties and ambient conditions) used as model inputs. The analysis used eighty-nine climate datasets from North America, from tropical (14.2° N) to boreal (65.0° N) zones, with large ranges in annual mean temperature (26.5°C in tropical to -11.8°C in boreal), annual precipitation (6,143 to 181 mm), annual snowfall (0 to 612 kg m-2), and altitude (3 to 2,824 m above mean see level). The sensitivity analysis showed that CWD decomposition was strongly affected by climate, geographical location and altitude, which together regulate the activity of both microbial and invertebrate wood-decomposers. CWD decomposition rate increased with increments in temperature and precipitation, but decreased with increases in latitude and altitude. CWD decomposition was also sensitive to wood size, density, position (standing vs downed), and tree species. The sensitivity analysis showed that fungi are the most important decomposers of woody debris, accounting for over 50% mass loss in nearly all climatic zones in North America. The model includes invertebrate decomposers, focusing mostly on termites, which can have an important role in CWD decomposition in tropical and some subtropical regions. The role of termites in woody debris decomposition varied widely, between 0 and 40%, from temperate areas to tropical regions. Woody debris decomposition rates simulated for eighty-nine locations in North America were within the published range of woody debris decomposition rates for regions in northern hemisphere from 1.6° N to 68.3° N and in Australia.


Asunto(s)
Madera/química , Animales , Australia , Carbono/química , Clima , Bosques , Hongos/química , Invertebrados/química , América del Norte , Suelo/química , Temperatura , Árboles/química
20.
PLoS One ; 16(7): e0254408, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34242323

RESUMEN

Coarse woody debris (CWD) is a significant component of the forest biomass pool; hence a model is warranted to predict CWD decomposition and its role in forest carbon (C) and nutrient cycling under varying management and climatic conditions. A process-based model, CWDDAT (Coarse Woody Debris Decomposition Assessment Tool) was calibrated and validated using data from the FACE (Free Air Carbon Dioxide Enrichment) Wood Decomposition Experiment utilizing pine (Pinus taeda), aspen (Populous tremuloides) and birch (Betula papyrifera) on nine Experimental Forests (EF) covering a range of climate, hydrology, and soil conditions across the continental USA. The model predictions were evaluated against measured FACE log mass loss over 6 years. Four widely applied metrics of model performance demonstrated that the CWDDAT model can accurately predict CWD decomposition. The R2 (squared Pearson's correlation coefficient) between the simulation and measurement was 0.80 for the model calibration and 0.82 for the model validation (P<0.01). The predicted mean mass loss from all logs was 5.4% lower than the measured mass loss and 1.4% lower than the calculated loss. The model was also used to assess the decomposition of mixed pine-hardwood CWD produced by Hurricane Hugo in 1989 on the Santee Experimental Forest in South Carolina, USA. The simulation reflected rapid CWD decomposition of the forest in this subtropical setting. The predicted dissolved organic carbon (DOC) derived from the CWD decomposition and incorporated into the mineral soil averaged 1.01 g C m-2 y-1 over the 30 years. The main agents for CWD mass loss were fungi (72.0%) and termites (24.5%), the remainder was attributed to a mix of other wood decomposers. These findings demonstrate the applicability of CWDDAT for large-scale assessments of CWD dynamics, and fine-scale considerations regarding the fate of CWD carbon.


Asunto(s)
Biomasa , Bosques , Madera , Minerales , Pinus taeda
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