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The northwestern pond turtle, Actinemys marmorata, and its recently recognized sister species, the southwestern pond turtle, A. pallida, are the sole aquatic testudines occurring over most of western North America and the only living representatives of the genus Actinemys. Although it historically ranged from Washington state through central California, USA, populations of the northwestern pond turtle have been in decline for decades and the species is afforded state-level protection across its range; it is currently being considered for protection under the US Endangered Species Act. Here, we report a new, chromosome-level assembly of A. marmorata as part of the California Conservation Genomics Project (CCGP). Consistent with the reference genome strategy of the CCGP, we used Pacific Biosciences HiFi long reads and Hi-C chromatin-proximity sequencing technology to produce a de novo assembled genome. The assembly comprises 198 scaffolds spanning 2,319,339,408 base pairs, has a contig N50 of 75 Mb, a scaffold N50 of 146Mb, and BUSCO complete score of 96.7%, making it the most complete testudine assembly of the 24 species from 13 families that are currently available. In combination with the A. pallida reference genome that is currently under construction through the CCGP, the A. marmorata genome will be a powerful tool for documenting landscape genomic diversity, the basis of adaptations to salt tolerance and thermal capacity, and hybridization dynamics between these recently diverged species.

The Global Panzootic Lineage (GPL) of the pathogenic fungusBatrachochytrium dendrobatidis(Bd) has caused severe amphibian population declines, yet the drivers underlying the high frequency of GPL in regions of amphibian decline are unclear. Using publicly availableBdgenome sequences, we identified multiple non-GPLBdisolates that contain a circular Rep-encoding single stranded DNA-like virus which we named BdDV-1. We further sequenced and constructed genome assemblies with long read sequences to find that the virus is likely integrated into the nuclear genome. Attempts to cure virus positive isolates were unsuccessful, however, phenotypic differences between naturally virus positive and virus negativeBdisolates suggested that BdDV-1 decreases the growth of its hostin vitrobut increases the virulence of its hostin vivo. BdDV-1 is the first described CRESS DNA mycovirus to increase host virulence with a distribution inversely associated with the emergence of the panzootic lineage.

The cellular signals that trigger pathogen recognition of its target hosts are critical components in the infection cycle. A new study describes the amphibian host cues that induce spore germination in the deadly pathogen that causes chytridiomycosis.

By altering the abundance, diversity, and distribution of species — and their pathogens — globalization may inadvertently select for more virulent pathogens. In Brazil’s Atlantic Forest, a hotspot of amphibian biodiversity, the pet trade has facilitated the co-occurrence of previously isolated enzootic and panzootic lineages of the pathogenic amphibian-chytrid (‘Bd’) and generated new virulent recombinant genotypes (‘hybrid’). Epidemiological data indicate that amphibian declines are most severe in hybrid zones, suggesting that coinfections are causing more severe infections or selecting for higher virulence. We investigated how coinfections involving these genotypes shaped virulence and transmission. Overall, coinfection favored the more virulent and competitively superior panzootic genotype, despite dampening its virulence and transmission. However, for the least virulent and least competitive genotype, coinfection increased both pathogen virulence and transmission. Thus, by integrating experimental and epidemiological data, our results provide mechanistic insight into how globalization can select for, and propel, the emergence of introduced hypervirulent lineages, such as the globally distributed panzootic lineage of Bd.

Made available in DSpace on 2021-06-25T10:47:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 In Brazil’s Atlantic Forest (AF) biodiversity conservation is of key importance since the fungal pathogen Batrachochytrium dendrobatidis (Bd) has led to the rapid loss of amphibian populations here and worldwide. The impact of Bd on amphibians is determined by the host's immune system, of which the skin microbiome is a critical component. The richness and diversity of such cutaneous bacterial communities are known to be shaped by abiotic factors which thus may indirectly modulate host susceptibility to Bd. This study aimed to contribute to understanding the environment-host–pathogen interaction determining skin bacterial communities in 819 treefrogs (Anura: Hylidae and Phyllomedusidae) from 71 species sampled across the AF. We investigated whether abiotic factors influence the bacterial community richness and structure on the amphibian skin. We further tested for an association between skin bacterial community structure and Bd co-occurrence. Our data revealed that temperature, precipitation, and elevation consistently correlate with richness and diversity of the skin microbiome and also predict Bd infection status. Surprisingly, our data suggest a weak but significant positive correlation of Bd infection intensity and bacterial richness. We highlight the prospect of future experimental studies on the impact of changing environmental conditions associated with global change on environment-host–pathogen interactions in the AF. Institute of Zoology Universität Hamburg, Martin-Luther-King-Platz 3 Laboratório de Herpetologia Depto de Biodiversidade Instituto de Biociências and Centro de Aquicultura (CAUNESP) Universidade Estadual Paulista - UNESP Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB) Departamento de Biologia Animal Instituto de Biologia Universidade Estadual de Campinas Department of Ecology and Evolutionary Biology Cornell University Department of Wildlife Fish and Conservation Biology University of California Davis Laboratório de Antígenos Bacterianos II Departamento de Genética Evolução Microbiologia e Imunologia Instituto de Biologia Universidade Estadual de Campinas, Caixa Postal 6109 Department of Biological Sciences The University of Alabama Department of Ecology and Evolutionary Biology University of Michigan Zoological Institute Technische Universität Braunschweig, Mendelssohnstraße 4 Laboratório de Herpetologia Depto de Biodiversidade Instituto de Biociências and Centro de Aquicultura (CAUNESP) Universidade Estadual Paulista - UNESP

Globalized infectious diseases are causing species declines worldwide, but their source often remains elusive. We used whole-genome sequencing to solve the spatiotemporal origins of the most devastating panzootic to date, caused by the fungus Batrachochytrium dendrobatidis, a proximate driver of global amphibian declines. We traced the source of B. dendrobatidis to the Korean peninsula, where one lineage, BdASIA-1, exhibits the genetic hallmarks of an ancestral population that seeded the panzootic. We date the emergence of this pathogen to the early 20th century, coinciding with the global expansion of commercial trade in amphibians, and we show that intercontinental transmission is ongoing. Our findings point to East Asia as a geographic hotspot for B. dendrobatidis biodiversity and the original source of these lineages that now parasitize amphibians worldwide., S.J.O., T.W.J.G., L.Br., A.Lo., A.A.C., D.S.S., E.A.C., C.M., J.B., D.M.A., F.C., and M.C.F. were supported through NERC (standard grant NE/K014455/1). S.J.O. acknowledges a Microsoft Azure for Research Sponsorship (subscription ID: ab7cd695-49cf-4a83-910a-ef71603e708b). T.W.J.G., A.Lo., A.A.C., D.S.S., E.A.C., C.M., J.B., D.M.A., F.C., and M.C.F. were also supported by the EU BiodivERsA scheme (RACE, funded through NERC directed grant NE/G002193/1 and ANR08-Biodiversa-002-03) and NERC (standard grant NE/K012509/1). M.C.F., E.A.C., and C.M. acknowledge the Nouragues Travel Grant Program 2014. R.A.F. was supported by an MIT/Wellcome Trust Fellowship. T.W.J.G. was supported by the People’s Trust for Endangered Species and the Morris Animal Foundation (D12ZO002). J.M.G.S. and M.C.F. were supported by the Leverhulme Trust (RPG-2014-273) and the Morris Animal Foundation (D16ZO-022). F.B. was supported by the ERC (grant ERC 260801–Big_Idea). D.M.A. was funded by Wellcome Trust grant 099202. J.V. was supported by the Hungarian Scientific Research Fund (OTKA K77841) and Bolyai János Research Scholarship, Hungarian Academy of Sciences (BO/00579/14/8). D.J.G. was supported by the Conservation Leadership Programme (grant 0134010) with additional assistance from F. Gebresenbet, R. Kassahun, and S. P. Loader. C.S.-A. was supported by Fondecyt Nº11140902 and 1181758. T.M.D.-B. was supported by the Royal Geographical Society and the Royal Zoological Society of Scotland with assistance from M. Hirschfeld and the Budongo Conservation Field Station. B.W. was supported by the National Research Foundation of Korea (2015R1D1A1A01057282). L.F.T. was supported by FAPESP (#2016/25358-3) and CNPq (#300896/2016-6). L.Be., L.F.S., and R.J.W. were supported by the Australian Research Council (FT100100375, DP120100811). A.A.C. was supported by a Royal Society Wolfson Research Merit award. J.H., A.La., and S.M. were funded by the Swedish Research Council Formas (grant no. 2013- 1389-26445-20). C.W. was funded by the National Research Foundation, South Africa. T.Y.J. and T.S.J. acknowledge NSF grant DEB-1601259. W.E.H. was funded by the NSERC Strategic and Discovery grant programs

Hybridization is increasingly recognized as an important force impacting adaptation and evolution in many lineages of fungi. During hybridization, divergent genomes and alleles are brought together into the same cell, potentiating adaptation by increasing genomic plasticity. Here, we review hybridization in fungi by focusing on two fungal pathogens of animals. Hybridization is common between the basidiomycete yeast species Cryptococcus neoformans × Cryptococcus deneoformans, and hybrid genotypes are frequently found in both environmental and clinical settings. The two species show 10−15% nucleotide divergence at the genome level, and their hybrids are highly heterozygous. Though largely sterile and unable to mate, these hybrids can propagate asexually and generate diverse genotypes by nondisjunction, aberrant meiosis, mitotic recombination, and gene conversion. Under stress conditions, the rate of such genetic changes can increase, leading to rapid adaptation. Conversely, in hybrids formed between lineages of the chytridiomycete frog pathogen Batrachochytrium dendrobatidis (Bd), the parental genotypes are considerably less diverged (0.2% divergent). Bd hybrids are formed from crosses between lineages that rarely undergo sex. A common theme in both species is that hybrids show genome plasticity via aneuploidy or loss of heterozygosity and leverage these mechanisms as a rapid way to generate genotypic/phenotypic diversity. Some hybrids show greater fitness and survival in both virulence and virulence-associated phenotypes than parental lineages under certain conditions. These studies showcase how experimentation in model species such as Cryptococcus can be a powerful tool in elucidating the genotypic and phenotypic consequences of hybridization.

Competition between genotypes is likely to be a key driver of pathogen evolution, particularly following a geographical invasion by distant strains. Theory predicts that competition between disease strains will result in the most virulent strain persisting. Despite its evolutionary implications, the role of strain competition in shaping populations remains untested for most pathogens. We experimentally investigated the in vivo competitive differences between two divergent lineages of the amphibian-killing chytrid fungus ( Batrachochytrium dendrobatidis , Bd ). These Bd lineages are hypothesized to have diverged in allopatry but been recently brought back into secondary contact by human introduction. Prior studies indicate that a panzootically-distributed, global lineage of Bd was recently introduced into southern Brazil, and is competitively excluding enzootic lineages in the southern Atlantic Forest. To test for differences in competitive ability between invasive and enzootic Brazilian Bd isolates, we coinfected a model host frog system which we developed for this study ( Hymenochirus curtipes ). We tracked isolate-specific zoospore production over the course of the coinfection experiment with chip-based digital PCR (dPCR). The globally invasive panzootic lineage had a competitive advantage in spore production especially during the first one to four weeks of infection, and on frogs that eventually succumbed to Bd infection. Our study provides new evidence that competitive pressure resulting from the human movement of pathogen strains can rapidly alter the genetics, community dynamics and spatial epidemiology of pathogens in the wild.

Latitudinal gradients are linked to the dynamics of infectious diseases. Both prevalence and infection intensity of the amphibian-killing fungus, Batrachochytrium dendrobatidis (Bd), vary with latitude. Here, we tested whether abiotic and biotic factors are associated with Bd infection prevalence and intensity along a large latitudinal gradient across the Brazilian Atlantic Forest. We detected a positive association between infection prevalence and infection intensity with latitude; elevation, temperature and precipitation best explained infection prevalence, while temperature best explained infection intensity. We also detected a positive association between species richness and Bd infections and associations between Bd infections with host reproductive biology and habitat type. This represents the longest and most thoroughly sampled latitudinal gradient of Bd in anuran populations. Our results corroborate earlier findings that abiotic factors are a major determinant of Bd infections and highlight the need for a better understanding of the role that species diversity plays in disease outcomes.

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is the emerging infectious disease implicated in recent population declines and extinctions of amphibian species worldwide. Bd strains from regions of disease-associated amphibian decline to date have all belonged to a single, hypervirulent clonal genotype (Bd-GPL). However, earlier studies in the Atlantic Forest of southeastern Brazil detected a novel, putatively enzootic lineage (Bd-Brazil), and indicated hybridization between Bd-GPL and Bd-Brazil. Here, we characterize the spatial distribution and population history of these sympatric lineages in the Brazilian Atlantic Forest. To investigate the genetic structure of Bd in this region, we collected and genotyped Bd strains along a 2400-km transect of the Atlantic Forest. Bd-Brazil genotypes were restricted to a narrow geographic range in the southern Atlantic Forest, while Bd-GPL strains were widespread and largely geographically unstructured. Bd population genetics in this region support the hypothesis that the recently discovered Brazilian lineage is enzootic in the Atlantic Forest of Brazil and that Bd-GPL is a more recently expanded invasive. We collected additional hybrid isolates that demonstrate the recurrence of hybridization between panzootic and enzootic lineages, thereby confirming the existence of a hybrid zone in the Serra da Graciosa mountain range of Paraná State. Our field observations suggest that Bd-GPL may be more infective towards native Brazilian amphibians, and potentially more effective at dispersing across a fragmented landscape. We also provide further evidence of pathogen translocations mediated by the Brazilian ranaculture industry with implications for regulations and policies on global amphibian trade.

Invasive plants are major drivers of habitat modification and the scale of their impact is increasing globally as anthropogenic activities facilitate their spread. In California, an invasive plant genus of great concern is Eucalyptus. Eucalyptus leaves can alter soil chemistry and negatively affect underground macro- and microbial communities. Amphibians serve as excellent models to evaluate the effect of Eucalyptus invasion on ground-dwelling species as they predate on soil arthropods and incorporate soil microbes into their microbiotas. The skin microbiota is particularly important to amphibian health, suggesting that invasive plant species could ultimately affect amphibian populations. To investigate the potential for invasive vegetation to induce changes in microbial communities, we sampled microbial communities in the soil and on the skin of local amphibians. Specifically, we compared Batrachoseps attenuatus skin microbiomes in both Eucalyptus globulus (Myrtaceae) and native Quercusagrifolia (Fagaceae) dominated forests in the San Francisco Bay Area. We determined whether changes in microbial diversity and composition in both soil and Batrachoseps attenuatus skin were associated with dominant vegetation type. To evaluate animal health across vegetation types, we compared Batrachoseps attenuatus body condition and the presence/absence of the amphibian skin pathogen Batrachochytrium dendrobatidis. We found that Eucalyptus invasion had no measurable effect on soil microbial community diversity and a relatively small effect (compared to the effect of site identity) on community structure in the microhabitats sampled. In contrast, our results show that Batrachoseps attenuatus skin microbiota diversity was greater in Quercus dominated habitats. One amplicon sequence variant identified in the family Chlamydiaceae was observed in higher relative abundance among salamanders sampled in Eucalyptus dominated habitats. We also observed that Batrachoseps attenuatus body condition was higher in Quercus dominated habitats. Incidence of Batrachochytrium dendrobatidis across all individuals was very low (only one Batrachochytrium dendrobatidis positive individual). The effect on body condition demonstrates that although Eucalyptus may not always decrease amphibian abundance or diversity, it can potentially have cryptic negative effects. Our findings prompt further work to determine the mechanisms that lead to changes in the health and microbiome of native species post-plant invasion.

Parasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into sterile culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to interested researchers worldwide as part of the BiodivERsA project RACE – here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been widely applied across at least 5 continents, 23 countries and in 62 amphibian species, and have been successfully used to isolate chytrids in remote field locations. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species (Batrachochytrium dendrobatidis) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened amphibian species and have improved our ability to work with this important group of emerging fungal pathogens.

Made available in DSpace on 2018-11-26T17:24:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Catalyzing New International Collaborations Grant from the National Science Foundation (NSF) The Global Panzootic Lineage of the fungus Batrachochytrium dendrobatidis (Bd-GPL) is threatening amphibians worldwide. In contrast, four lineages (Bd-Brazil, Bd-CH, Bd-Cape, and Bd-Korea) that diverged early in the history of Bd have not yet been directly linked to amphibian declines. Bd likely evolves in response to strong selective pressure imposed by hosts and the environment, leading to differences among pathogen phenotypes and genotypes that may directly affect virulence. Here, We report on variation in phenotype, genotype, and virulence of Bd-Brazil and Bd-GPL. Specifically, we (i) used a controlled infection experiment to compare virulence between one Bd-Brazil and three Bd-GPL isolates on a North American amphibian host (Lithobates sylvaticus), (ii) tested for relative phenotypic and genotypic differentiation among Bd isolates from Brazil, and (iii) tested for possible correlations between environmental variables and Bd phenotypes. We found substantial variation in virulence among Bd-GPL isolates and found that our Bd-Brazil isolate showed virulence comparable to an average North American Bd-GPL. North American hosts infected with a Bd-GPL isolate from Panama did not show significant mortality. Bd phenotypes varied significantly across sampling locations; these phenotypes were neither spatially clustered nor correlated with any environmental variables. Additionally, we found a surprising lack of correlation between genotypic divergence and zoospore and zoosporangium sizes in our sample. Although Bd-Brazil was less virulent infecting L. sylvaticus than one Bd-GPL isolate, this endemic lineage still caused-50% mortality in our experimental Ndrth American hosts, This indicates that Bd-Brazil has the potential to kill amphibians if introduced to na ve wild populations. Our findings underscore that characterizing virulence of multiple Bd isolates and lineages is important for understanding the evolutionary history and diversity of Bd. (C) 2016 Elsevier Ltd and British Mycological Society. All rights reserved. Univ Estadual Paulista, Dept Zool, BR-13506900 Rio Claro, SP, Brazil James Cook Univ, Coll Marine & Environm Sci, Townsville, Qld 4811, Australia Cornell Univ, Dept Ecol & Evolutionary Biol, Ithaca, NY 14853 USA Univ Estadual Campinas, Dept Biol Anim, BR-13083862 Campinas, SP, Brazil Univ Michigan, Dept Ecol & Evolutionary Biol, Ann Arbor, MI 48109 USA Univ Estadual Campinas, Dept Genet Evolugao Bioagentes, BR-13083862 Campinas, SP, Brazil Univ Maine, Sch Biol & Ecol, Orono, ME 04469 USA Univ Estadual Paulista, Dept Zool, BR-13506900 Rio Claro, SP, Brazil FAPESP: 2011/51694-7 CNPq: 405285/2013-2 CNPq: 302589/2013-9 CNPq: 300980/2014-0 CNPq: 312895/2014-3 Catalyzing New International Collaborations Grant from the National Science Foundation (NSF): OISE-1159513

Made available in DSpace on 2019-10-04T12:40:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-31 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Deutsche Forschungsgemeinschaft-DFG Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Department of Biological Sciences at the University of Alabama Wildlife disease dynamics are strongly influenced by the structure of host communities and their symbiotic microbiota. Conspicuous amphibian declines associated with the waterborne fungal pathogen Batrachochytrium dendrobatidis (Bd) have been observed in aquatic-breeding frogs globally. However, less attention has been given to cryptic terrestrial-breeding amphibians that have also been declining in tropical regions. By experimentally manipulating multiple tropical amphibian assemblages harbouring natural microbial communities, we tested whether Bd spillover from naturally infected aquatic-breeding frogs could lead to Bd amplification and mortality in our focal terrestrial-breeding host: the pumpkin toadlet Brachycephalus pitanga. We also tested whether the strength of spillover could vary depending on skin bacterial transmission within host assemblages. Terrestrial-breeding toadlets acquired lethal spillover infections from neighbouring aquatic hosts and experienced dramatic but generally non protective shifts in skin bacterial composition primarily attributable to their Bd infections. By contrast, aquatic-bleeding amphibians maintained mild Bd infections and higher survival, with shifts in bacterial microbiomes that were unrelated to Bd infections. Our results indicate that Bd spillover from even mildly infected aquatic-breeding hosts may lead to dysbiosis and mortality in terrestrial-breeding species, underscoring the need to further investigate recent population declines of terrestrial-breeding amphibians in the tropics. Univ Alabama, Dept Biol Sci, Tuscaloosa, AL 35847 USA Univ Massachusetts, Dept Biol, Boston, MA 02125 USA Texas State Univ, Dept Biol, San Marcos, TX 78666 USA Univ Estadual Campinas, Dept Anim Biol, BR-13083865 Campinas, SP, Brazil Univ Calif Berkeley, Dept Environm Sci Policy & Management, Berkeley, CA 94720 USA Univ Sao Paulo, Dept Ecol, BR-05508090 Sao Paulo, SP, Brazil Helmholtz Ctr Infect Res, Dept Genome Analyt, D-38124 Braunschweig, LS, Germany Braunschweig Univ Technol, Zool Inst, Div Evolutionary Biol, D-38106 Braunschweig, LS, Germany Univ Estadual Paulista, Dept Zool, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Paulista, Aquaculture Ctr CAUNESP, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Paulista, Dept Zool, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Paulista, Aquaculture Ctr CAUNESP, BR-13506900 Rio Claro, SP, Brazil CNPq: 400177/2014-5 CNPq: 300896/2016-6 CAPES: 88881.062205/2014-01 Deutsche Forschungsgemeinschaft-DFG: VE247/9-1 FAPESP: 2013/50741-7 FAPESP: 2016/25358-3

BackgroundUnderstanding of the physiological effects of chytridiomycosis is crucial to worldwide amphibian conservation. Therefore, we analyzed the cardiac function of two anuran species (Xenopus laevisandPhysalaemus albonotatus) with different susceptibilities to infection by the causative agent of chytridiomycosis,Batrachochytrium dendrobatidis(hereafterBd).MethodsWe analyzed thein situheart rate (fH- bpm), relative ventricular mass (RVM -%), and Ca2+handling in heart ofBdinfected animals compared to uninfected controls of both study species.ResultsBdinfection resulted in a 78% decrease in contraction force values inP. albonotatuswhen compared to the less susceptibleX. laevis. This negative effect was even more evident (82%) for the cardiac pumping capacity. The time to reach peak tension was 125% longer inP. albonotatusthan inX. laevis, and cardiac relaxation was 57% longer.DiscussionThese results indicate a delay in the cardiac cycle ofP. albonotatuson a beat-to-beat basis, which was corroborated by the bradycardia observedin situ. In summary,Bd-sensitive species present impaired cardiac function, which could be a factor in mortality risk. The more pronounced effects ofBdinP. albonotatusmay not only result from electrolyte imbalance, as previously reported, but also could be an effect of toxins produced byBd. ForX. laevis, the ability to promote cardiac adjustments seems to be an important homeostatic feature that allows greater tolerance to chytridiomycosis. This study provides new physiological mechanisms underlying the tolerance or susceptibility of amphibian species to chytridiomycosis, which determine their adaptability to survive in the affected environments.

Made available in DSpace on 2018-11-26T16:32:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-04-01 National Science Foundation Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Environmental factors can limit the distribution of organisms if they are not able to respond through phenotypic plasticity or local adaptation. Batrachochytrium dendrobatidis (Bd) is a broadly distributed pathogen, which shows spatially patterned genotypic and phenotypic variation; however, information on the functional consequences of this variation on disease dynamics in natural hosts is limited. We genotyped and quantified variation in Bd phenotypes across an elevational gradient and quantified host infection dynamics at each site. All Bd strains were members of the global panzootic lineage yet differed in phenotype. We hypothesize that this phenotypic variance results from adaptive processes due to the interaction between pathogen, hosts, and environment. We detected a correlation between zoospore and zoosporangia sizes and a positive association between zoosporangia size and Bd prevalence. Given that Bd phenotype predicted disease status in our wild populations, we developed an index to identify critical environments where the fungus could be more deleterious. (C) 2015 Elsevier Ltd and The British Mycological Society. All rights reserved. Univ Estadual Campinas, Inst Biol, Dept Biol Anim, Lab Hist Nat Anfibios Brasileiros LaHNAB, BR-13083862 Sao Paulo, Brazil Univ Estadual Paulista, Dept Zool, BR-13506900 Sao Paulo, Brazil Univ Michigan, Dept Ecol & Evolutionary Biol, Ann Arbor, MI 48109 USA Texas State Univ, Dept Biol, San Marcos, TX 78666 USA Univ Estadual Campinas, Inst Biol, Dept Genet Evolucao & Bioagentes, BR-13083862 Sao Paulo, Brazil Cornell Univ, Dept Ecol & Evolutionary Biol, Ithaca, NY 14850 USA Univ Estadual Paulista, Dept Zool, BR-13506900 Sao Paulo, Brazil National Science Foundation: OISE-1159513 National Science Foundation: DBI-0905810 FAPESP: 2011/51694-7 FAPESP: 2012/04160-0 FAPESP: 2012/51694-7 CNPq: 405285/2013-2 CNPq: 312895/2014-3

Cystidia of Suillus americanus and S. granulatus (Boletales) were examined cytochemically and ultrastructurally with cells prepared by freeze substitution. We present the first study showing ultrastructural details and cytological functions of the cystidium to be conserved in two closely related species. The results are presented for inclusion in the AFTOL Structural and Biochemical Databasehttp://aftol.umn.eduto aid in the application of morphological characters to phylogenetic studies. The cystidia of these Suillus species appear to be united by a series of conserved characters, including specialized secretion mechanisms, smooth tubular endoplasmic reticulum and abundant free ribosomes. The conservation of these subcellular traits among members of this genus suggests that ultrastructural details of cystidia may provide a suite of phylogenetically informative characters. Inclusion of such characters in phylogenetic analyses might resolve or provide support for monophyletic groups at the level of family or genus.

Ultrastructure of the septal pore apparatus and nuclear division of Auriscalpium vulgare (Russulales) was examined with freeze substitution and is presented for inclusion in the AFTOL Structural and Biochemical Database (http://aftol.umn.edu). Previously unreported septal characters for the Russulales (Agaricomycotina) were observed: Septa of the hymenophore had bell-shaped perforated septal pore caps that may extend along the septum and a zone of organelle exclusion surrounded the septal pore apparatus. Metaphase I of meiosis and metaphase of mitosis were similar. Globular spindle pole bodies with electron-opaque inclusions were set within polar fenestrae of the nuclear envelope. The nuclear envelope was mostly intact with occasional gaps. Fragments of endoplasmic reticulum were present near the spindle pole bodies but did not form a polar cap. Structural characters may distinguish one or more clades of the Agaricomycotina and provide additional signal in phylogenetic analyses.

Phylogenetic placement of the infrageneric section Hygrometrici (genus Marasmius sensu stricto) in prior molecular phylogenetic studies have been unresolved and problematical. Molecular analyses based on newly generated ribosomal nuc-LSU and 5.8S sequences resolve members of section Hygrometrici to the family Physalacriaceae. The new genus Cryptomarasmius is proposed to accommodate members of Marasmius section Hygrometrici. Fourteen species belonging to section Hygrometrici whose available type specimens bear morphological features corresponding to the new genus are formally combined in Cryptomarasmius. Taxonomic transfers are made only for taxa in which type specimens have been studied and/or representative material sequenced. Although other species placed in section Hygrometrici may belong in Cryptomarasmius, further transfers are not proposed until additional studies on type material are conducted.

Understanding the evolutionary history of microbial pathogens is critical for mitigating the impacts of emerging infectious diseases on economically and ecologically important host species. We used a genome resequencing approach to resolve the evolutionary history of an important microbial pathogen, the chytrid Batrachochytrium dendrobatidis (Bd), which has been implicated in amphibian declines worldwide. We sequenced the genomes of 29 isolates of Bd from around the world, with an emphasis on North, Central, and South America because of the devastating effect that Bd has had on amphibian populations in the New World. We found a substantial amount of evolutionary complexity in Bd with deep phylogenetic diversity that predates observed global amphibian declines. By investigating the entire genome, we found that even the most recently evolved Bd clade (termed the global panzootic lineage) contained more genetic variation than previously reported. We also found dramatic differences among isolates and among genomic regions in chromosomal copy number and patterns of heterozygosity, suggesting complex and heterogeneous genome dynamics. Finally, we report evidence for selection acting on the Bd genome, supporting the hypothesis that protease genes are important in evolutionary transitions in this group. Bd is considered an emerging pathogen because of its recent effects on amphibians, but our data indicate that it has a complex evolutionary history that predates recent disease outbreaks. Therefore, it is important to consider the contemporary effects of Bd in a broader evolutionary context and identify specific mechanisms that may have led to shifts in virulence in this system., Instituto de Botánica "Dr. Carlos Spegazzini"