Welcome to IMC 2018 International Mycological Congress
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The origin and phylogenetic diversity of lichen-forming fungi in the Basidiomycota
- J. Lawrey
- M. Dal Forno
- R. Luecking
Abstract
Abstract
Lichenization is a major evolutionary lifestyle in Fungi, with approximately 20,000 species currently recognized and up to 28,000 estimated. Although most lichenized species (99.7%) are members of the Ascomycota, basidiolichens have evolved independently and relatively recently in at least four separate orders, making them excellent models to study the evolution of lichenization, since descent from non-lichenized ancestors can be reliably established for many groups. Molecular data have revolutionized the classification of Basidiomycota, including lichenized lineages, reflected in the changes to classification attempts made throughout history, starting with Zahlbruckner and during recent decades by Oberwinkler. Two surprising recent classification-altering discoveries are that clavarioid lichens belong to unrelated lineages and that mushroom-forming and corticioid lichens are closely related. Molecular approaches also led to the discovery of many new taxa. At present, over 300 species of basidiolichens are recognized and more than 700 are predicted, compared to only 40 species distinguished less than a decade ago. The highest diversity of basidiolichens is in the agaric family Hygrophoraceae, which harbors hundreds of newly described species in two distinctive lineages representing separate lichenization events. One of these (Dictyonema s.l.) is tropical to tropical-alpine and consists of species with a cyanobacterial photobiont, and the other (Lichenomphalia s.l.) is mainly arctic-alpine to tropical-alpine with species having a green algal photobiont. The Dictyonema s.l. clade is notable for an unusually high diversification rate, given its relatively young phylogenetic age, and a remarkable diversity of thallus morphologies, representing an evolutionary transition from loosely organized filamentous crusts with separate basidiocarps to highly derived foliose forms with integrated basidiocarps. Clades outside the Hygrophoraceae represent lichenization events that led to either little or no subsequent diversification (possibly Athelia in the Atheliales), genus-level diversification (Multiclavula in the Cantharellales) or family-level diversification with several genera and a growing number of known species (Lepidostromatales). It is expected that increased attention to the lichenized Basidiomycota will yield further insights into the process of lichenization and symbiosis in general, as reflected by the wide variety of topics featured in this symposium on 'basidiolichenology'.
The genus Cora in Colombia: diversification of a hyperdiverse, basidiolichen-forming clade in the northern Andes
- B. Moncada
- M. Dal Forno
- R. Lücking
Abstract
Abstract
The genus Cora comprises foliose basidiolichens with resupinate hymenophore. This group was first revised in a monograph of the genus Dictyonema s.lat. in 1978 by Parmasto, at which time a single foliose species was accepted under the name D. pavonium (later changed to D. glabratum). Before 1978, historically a total of five species had been described, under the epithets ciferrii, glabrata, gyrolophia, pavonia (≡ montana), and reticulifera. The group remained monospecific until 2004, when a new species was discovered. Based on subsequent molecular studies, the genus Cora was formally reinstated, and accumulation of data on the ITS barcoding locus, together with detailed field studies, showed that this genus included a much higher number of taxa than previously assumed. A 2013 revision recognized 14 species, including reinstatement of the five historical epithets, and in 2014, 116 species were distinguished phylogenetically, based on 338 ITS accessions. The most recent study, dating from 2017, distinguished 189 species based on 651 ITS accessions and five historical epithets, 92 of which are formally described. In the 2014 study, a grid-map approach predicted that Cora may contain more than 450 species, a dramatic increase from a single taxon recognized until a decade before. Most of the currently recognized 189 species are restricted to the northern Andes and particularly Colombia. In the 2014 study, 46 ouf of 116 species (40%) were from Colombia (corresponding to 145 out of 338 ITS accessions or 43%), with 36 species (31%) exclusively known from that country. In the 2017 work, 87 ouf of 189 species (46%) were present in Colombia (corresponding to 366 out of 651 ITS accessions or 56%), with 73 species (39%) exclusively known from there. Of the 92 described species, 34 (37%) have their type locality in Colombia. This is in part due to sampling effort: of the 209 sampling grids defined in the 2014 study, 15 (7%) correspond in part or entirely to Colombia, roughly mirrowing Colombia's proportional area cover within the target area (6%). Within the target area, 24 grids were sampled, three of which well-sampled, with five sampled (21%) and one well-sampled (33%) corresponding to Colombia, denoting a proportionally higher sampling effort in that country. However, the increased sampling effort also reflects the fact that Cora is most diverse in the wet (sub-)paramos of the northern Andes, characterized by the plant genus Espeletia, which range from Venezuela to Ecuador and are most extensively developed in Colombia. Molecular dating suggests that the diversification of Cora is temporally correlated with the uplift of the northern Andes during the past 10 million years, underlining the importance of Colombia as the center of diversification of the genus. Three examples of current studies in Colombia further highlight this notion: (1) testing the grid prediction method by visiting the southernmost Colombian grid, comparing detected and predicted number of species; (2) analyzing patterns of local endemism in the highly threatened Colombian paramos; and (3) documenting the discovery of novel taxa in the context of urban expansion in the metropolitan area of Bogotá.
Diversity and evolution of lichenized Basidiomycota from Colombia
- L. Coca
- R. Lücking
- B. Moncada
- M. Dal Forno
Abstract
Abstract
Basidiolichens are the morphological and physiological result of the symbiotic relationship between a basidiomycete fungus and green alga or cyanobacteria. Less than 1% of all lichen fungi are found in the Basidiomycota, whereas over 99% belong in the Ascomycota. However, even if comparatively low in species, basidiolichens appear in independent lineages in three orders: Agaricales (Acantholichen, Cora, Corella, Cyphellostereum, Dictyonema, Lichenomphalia, Semiomphalina), Cantharellales (Multiclavula) and Lepidostromatales (Ertzia, Lepidostroma, Sulzbacheromyces). Some of these groups are morphologically similar but phylogenetically unrelated, so their phenotypes have evolved independently in similar ways, such as in the genera Multiclavula and Sulzbacheromyces, both of which have a clavarioid basidiocarps and crustose thalli, hard to distinguish without genetic data. Thus, molecular methods are an important tool to elucidate the evolutionary relationships and classification in these lichen fungi. With the objective of recognizing the phylogenetic position and taxonomic identity of lichenized, mushroom-like Basidiomycota in Colombia, fresh material was collected in major Colombian biomes (Andes, Amazonas, and Chocó) and ITS barcode sequences were obtained, proving the first records of several of the aforementioned genera for Colombia. Based on phylogenetic analysis we propose three new and semi-cryptic species in the genus Sulzbacheromyces from the Amazon and the Chocó, a new polymorphic species of Multiclavula from the paramo region, a new Acantholichen without acanthohyphidia (previously considered a synapomorphy of this group), and a new non-filamentous species in Dictyonema clade as a potentially new genus. Their morphology, anatomy and phylogenetic relationships are described and discussed.
The Basidiolichens in China
- D. Liu
- L. Wang
- X. Wang
- B. Goffinet
- J. Hur
Abstract
Abstract
Lichenization is a successful strategy of establishing a stable mutualistic relationship of fungi with phycobionts. However, lichens involve almost exclusively ascomycetes associated with either green algae or cyanobacteria, and some basidiomycetes which compose a polyphyletic assemblage of Agaricales, Cantharellales, Corticiales, and Lepidostromatales containing ca. 172 known species with most of the diversity occurring in the Hygrophoraceae (Agaricales), particularly in the genera Cora, Dictyonema, and Lichenomphalia. In China, four genera and twelve species, Dictyonema (3 spp.), Lichenomphalia (3 spp.), Lepidostroma (1 spp.), Multiclavula (5 spp.), were previously reported, but most of them have no molecular data and the phylogenetic systematical position is uncertain. In order to clarify basidiolichens species flora in China, field surveys were conducted around China, covering Fujian, Guizhou, Hainan, Sichuan, Taiwan, Yunnan, Xizang province, then morphology of old (collected in last several decades) and newly collected specimens were examined under the microscope. Newly sequenced species (18S, 28S, ITS) were combined with those published on GenBank and used for maximum likelihood analysis and Bayesian inference to investigate the phylogenetic relationships. Based on morphology, phylogeny and literatures, the basidiolichens in China were revised, specimens from China regarded as Multiclavula fossicola and M. sinensis belong to the Lepidostromatales, and are transferred to Sulzbacheromyces. Chinese reports of M. clara and M. vernalis belong to species of Lepidostromatales and specimens identified as M. mucida belong to the non-lichenized genus Clavaria. Hence, evidence of Multiclavula occurring in China is lacking. Similarly, L. calocerum is excluded from the Chinese flora. The recently described L. asianum should be regarded as conspecific with S. sinensis, and detail observation on this species variation under different micro-ecology was recorded. Consequently, 2 family, 3 genera and 12 species were confirmed, including three newly described species: Dictyonema yunnanum, Sulzbacheromyces bicolor and S. yunnanensis, and two new combinations: S. fossicolus (= Multiclavula fossicola), S. sinensis (= M. sinensis), and one new record species: Lichenomphalia velutina. In addition, following basidiolichens were added into the Chinese lichen flora: Dictyonema scabridum, D. sericeum, D. thelephora, Lichenomphalia hudsoniana, L. luteovitellina, L. umbellifera.
Unexpected basidiolichen diversity discovered in lowland Brazilian forests
- M. Cáceres
- M. Dal Forno
- F. Barreto
- A. Aptroot
Abstract
Abstract
Basidiolichens comprise a diverse ecological assemblage from a few different phylogenetic lineages, mainly in the Hygrophoraceae. Basidiolichens are mostly known from cool climates and are by far most diverse in montane regions in the Neotropics, both at genus and species level. Exceptions are the genus Sulzbacheromyces and crustose species of Dictyonema, which occur in dry and wet tropical lowland areas around the world. Brazil is the country with the highest lichen biodiversity on Earth, but much of this diversity remains as yet undiscovered. A 5-year programme of field trips to Amazonian and Atlantic rain forests, as well as to Caatinga and Cerrado regions in N and NE Brazil, revealed that basidiolichens are quite common in these lowland forest biomes and more diverse than previously known. Sulzbacheromyces is not only occurring in dry biomes, but present everywhere in Amazonian and Atlantic rain forests, often found on termitaria, a substratum that was until recently rarely explored for lichens. Crustose species of Dictyonema are omnipresent in all forest types and on all available substrata (including rock and living leaves), also in dry Cerrado forests, where they seem very much out of place. A large conchate Dictyonema of the sericeum-group was found on twigs just a few kilometres from the Atlantic Ocean; species of this group are characteristic for wet mountain forests, and there is only one previous lowland record from Thailand. Cora is the most speciose genus of basidiolichens. It is most speciose on soil, rock and low shrubs in mountain regions of the Neotropics, with only one Palaeotropical species known so far. The new species Cora itabaiana was described from a similar habitat in NE Brazil, but from low elevation. Surprisingly, a species of Cora was even found seven meters high on a (fallen) tree in an Atlantic rain forest reserve in Alagoas. As there is only rarely access to this specific habitat, it might indicate that Cora is more common as epiphyte in lowland areas. A possibly undescribed species of the genus Lepidostroma, a genus which was so far known only from the Andes and mountains in Mexico and Central America, was found to be locally common in disturbed places such as road banks in Atlantic rain forest. The basidiolichens found in Brazilian lowland forests are not phylogenetically related, but do belong to at least six different lineages, and the representatives are more related to species from Neotropical mountains than to each other. There is thus no evidence that the Brazilian lowland forest region is a center of speciation in the group. Only a very small percentage of the tropical lowlands has as yet been investigated by lichenologists. Our results suggest the existence of considerable unexplored basidiolichen diversity in Neotropical lowland forests.
Microbiome of basidiolichens in the Dictyonema clade (Hygrophoraceae, Agaricales)
- M. Dal Forno
- J. Lawrey
- R. Lücking
- M. Sikaroodi
- P. Gillevet
- E. Schuettpelz
- M. Grube
Abstract
Abstract
The Dictyonema clade, also known as Dictyonema sensu lato, is the most species-rich group of basidiolichens, with 136 currently accepted species in five genera. The clade occurs worldwide, but has its highest diversity in the Neotropics. The group shows a remarkable diversity of morphologies; the basal clade of Cyphellostereum and the genus Dictyonema sensu stricto are filamentous, while the other three genera (Acantholichen, Corella and Cora) are squamulose to mostly foliose. The photobionts of these lichens are cyanobacteria of genus Rhizonema, but relatively little is known about the associated microbiomes of these basidiolichens. Here, our main objectives were to investigate these microbiomes in different genera and species belonging to the Dictyonema clade to reveal whether microbial patterns found in herbarium samples were similar to specimens recently removed from their natural habitat. We first sequenced a partial region of the 16S rRNA gene (covering variable regions one and two) with multi-tag pyrosequencing (MTPS) in a 454 Roche instrument for 697 samples from 22 countries representing all major clades within Dictyonema. Then, we sequenced another region of the16S rRNA gene from 192 samples utilizing the Illumina MiSeq platform following the procedures of the Earth Microbiome Project. We found that the most abundant non-photobiont bacteria in these basidiolichens belonged to the Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Chloroflexi. The most common Proteobacteria are Alphaproteobacteria, in agreement with previous studies of ascolichens. Our preliminary results show that genera with filamentous morphology include a higher number of bacterial OTUs than foliose samples and that only a small percentage of OTUs are found in both filamentous and foliose basidiolichens. Finally, we observed that historical herbarium samples showed a decreased number of photobiont reads with metabarcoding sequencing, drastically changing the abundance pattern of bacterial taxa. Our results provide, for the first time, important insight into basidiolichen microbiomes and advance the current knowledge of these complex symbioses.
Shared versus independent losses: evolutionary consequences of intracellular parasitism in cryptic Fungi
- C. Quandt
- T. James
Abstract
Abstract
Phylogenomic analyses have suggested that a clade comprising eukaryotic parasites with the smallest known genomes, Microsporidia, and the phylum known primarily from environmental sequences, Rozellomycota, are at the base of the fungal phylogeny. However, the ecological and genetic similarities between these distant relatives remains unclear. Recently we compared genome data of Rozellomycota and Microsporidia with the newly acquired nuclear and mitochondrial genomes of Paramicrosporidium saccamoebae – an intranuclear parasite of amoebae. Our analyses demonstrate that Microsporidia are nested within Rozellomycota, which forms a paraphyletic clade. Comparative analysis revealed that P. saccamoebae shares more gene content with distantly related Fungi than with its closest relatives, suggesting that genome evolution in Rozellomycota and Microsporidia has been affected by repeated and independent gene losses, possibly as a result of variation in parasitic strategies (e.g. host and subcellular localization) or due to multiple transitions to parasitism. To understand if this represents a larger pattern of independent gene loss within the clade, we have sequenced the genomes of new rozellids and another amoeba-parasite that previous work suggests may be the closest relative to Microsporidia. Here we will explore the variation in gene content and genome evolution within this clade of intracellular parasites.
Using codon usage bias to predict ecologically adaptive metabolic pathways in the budding yeast subphylum
- A. Labella
- D. Opulente
- C. Hittinger
- A. Rokas
Abstract
Abstract
Since diverging about a half-a-billion years ago, the 1,000+ yeast species of the subphylum Saccharomycotina have diversified into every biome on Earth. The diversity of yeast ecological adaptation is underpinned by their ability to utilize a wide range of substrates and grow in a variety of environments. Traditionally, metabolic pathways that are key for yeast ecological adaptation have been identified through functional experiments in the laboratory, statistical analysis of associations between traits and environments, and by examining signatures of selection in the genes encoding metabolic enzymes. One genomic signature that has proven especially powerful at predicting gene activity, but has yet to be widely employed in evolutionary ecological research, is codon usage bias or the differential use of synonymous codons within and between genomes. The strongest driver of genome-wide codon usage bias patterns is G/C mutational bias. Codon usage bias at the level of individual genes, however, is a consequence of selection for translational efficiency, and therefore, gene level bias is strongly associated with gene expression. We expect that highly expressed genes will show codon usage bias in favor of optimally translated codons and that networks of co-expressed genes will show bias in favor of the same set of codons. In this work, we use species-specific gene-based estimates of codon usage bias (as a proxy for genes’ expression levels) to predict metabolic pathways that are highly active across the genomes of 332 budding yeast species. These active metabolic pathways are then compared to the known habitat features of these 332 budding yeast species to identify significant associations between highly active metabolic pathways and habitat features. In my presentation, I will report the results of these analyses. Identification of significant associations between metabolic activity predicted by codon usage bias analysis and habitat features will provide insight into which metabolic capabilities may be responsible for adaptation to specific environments. More broadly, this work also sheds light on the ability of codon usage bias to be more broadly used to predict ecologically relevant genes and pathways in other microbes--especially those that are currently unculturable.
The role of gene flow in rapid adaptive evolution of fungal plant pathogens: a comparative population genomics study
- A. Feurtey
- D. Stevens
- C. Eschenbrenner
- W. Stephan
- E. Stukenbrock
Abstract
Abstract
Antagonistic co-evolution between pathogens and their hosts can drive rapid adaptive changes in both partners. Pathogens exert a strong selection pressure on their hosts, in particular on immune defense genes. At the same time, host resistance can be overcome in the pathogen evolving to escape host recognition or to suppress host defenses. The genetic innovations allowing rapid adaptation in this evolutionary “arms-race” can have various origins including mutational events, sexual recombination and gene flow. Genome-based studies of fungal pathogens have revealed a frequent contribution of inter-specific gene exchange in rapid evolution. We used a population genomics approach based on de novo assemblies of genomes and whole genome alignments to characterize the distribution of highly variable regions in the fungal wheat pathogen Zymoseptoria tritici. These regions are found throughout the genome, comprise around 5% of the total genome size and overlap with 600 predicted coding sequences. We performed window based phylogenetic analyses align the genome alignment and show that the highly variable regions overlap with regions of showing signature of past interspecific hybridization events. We detect a similar pattern in the closely related wild grass pathogen, Zymoseptoria ardabiliae, and some hybridization events have involve these two species. Overall, our results demonstrate a significant impact of frequent interspecific hybridization on the genome evolution of this important wheat pathogen. We speculate that gene flow act to fuel arms race evolution of Z. tritici with its host.
Coccidioidomycosis in the surrounding landmasses of the Caribbean Sea is caused by cryptic Coccidioides posadasii populations
- B. Barker
- M. Teixeira
- P. Alvarado
- G. Thompson
- E. Arathon
- C. Canteros
Abstract
Abstract
Coccidioides posadasiicauses coccidioidomycosis in arid regions of the Americas. C. posadasiiis comprised of at least two populations; Arizona (AZ) and Texas/Mexico/South America (TXMXSA). The exact range of C. posadasiiin Central and South America is undetermined for many reasons. For one, the disease is sub-notified to local health departments. Second, fewer than 1,000 total cases across the region have been reported. The Caribbean region is bordered by the Caribbean Sea, and the surrounding continental landscape and islands may play an important role in the dispersion of C. posadasiithrough Mexico, Guatemala and Venezuela. To define the distribution of C. posadasiipopulations in Central and South America, we sequenced the genomes of 6 clinical isolates from Venezuela, 1 from Argentina, 2 from Mexico, 1 from Texas and 1 from Florida. References were assembled using the Unmanned Genome Assembly Pipeline using SPAdes as well the Pilon toolkit. Weincorporated 52 published genomes from C. posadasiito identify the genetic background of newly sequenced strains and develop hypotheses regarding the dispersion into Central and South America.Maximum Likelihood methods implemented in IQ-TREE software using jModelTest for model selection and 1,000 ultrafast bootstraps with Shimodaira-Hasegawa-like approximate likelihood ratio test were performed for branch confidence. The genealogical concordance level was tested using the Bayesian concordance analysis implemented in the BUCKy. To avoid linkage disequilibrium effect, the SNP matrix was assessed in 2500bp blocks. Posterior tree distribution of each locus was individually tested via MrBayes under GTR nucleotide substitution model. SNP matrices were run using two independent Markov Chain Monte Carlo simulations and four chains for 10 million generations with samples collected every 1,000 generations. Tracer was used to check convergence between the two chains and individual loci. Time-scaled phylogenies were calculated for timing analyses in BEAST. Trees topologies were visualized using FigTree. Comparative phylogenomic analyses reveal that clinical strains from Guatemala and Venezuela are genetically isolated from the well described populations AZ and TXMXSA, whereas the new Texan, Mexican and Argentinian isolates cluster with TXMXSA as expected. Analysis indicates that limited gene flow exists between Guatemala and AZ populations, whereas we observe nearly complete reproductive isolation from both AZ and TXMXSA among the newly sequenced Venezuela isolates. Interestingly, the isolate from a Florida patient was paraphyletic to the Venezuela/Guatemala cluster. Based on these observations, we propose new patterns of dispersion and endemicity through Central and South America. We provide strong evidence that the South American continent was colonized by at least two ancestral populations: one by a TXMXSA ancestral genotype, and the second by a Guatemalan ancestral genotype. Isolates from Brazil, Argentina and Paraguay cluster within the TXMXSA cluster whereas the Venezuelan clade shares a common ancestor with the Guatemalan cluster and together forms a newly designated “Caribbean” population, including the isolate from Florida, which is distinct from either AZ or TXMXSA. We propose that the Venezuela lineage was purified during migration through Central America to the semi-arid regions of the Paraguanápeninsula and the depression valleys of Lara and Falcon states.
Genome-wide survey for understanding genetic basis of morphological evolution of septal pore cap in Agaricomycetes
- T. Iizuka
- K. Ikeo
Abstract
Abstract
Understanding genetic basis of morphological evolution is essential for clarifying the evolutionary history of fungi. To understand the evolution of Agaricomycetes, morphological character of septal pore cap (SPC) is one of the key characters to distinguish taxonomy. In our study, we are focusing three phenotypes of SPC (vesiculate, imperforate and perforate) and searched candidate causal mutation of the differences of SPC types from fungal genome sequences. Among these three phenotypes, vesiculate SPC is known as the most ancestral characters. After the emergence of imperforate SPC from vesiculate SPC, perforate SPC had been evolved from imperforate SPC at multiple times independently (morphological independent evolution). The objective of this research is detecting mutation correlated with morphological evolution of these three types of SPC in amino acid sequence level. As the first step, for detecting the gene correlated with the evolution from imperforate SPC to perforate SPC, we searched genes that has parallel substitutions correlated with the emergence of perforate SPC from imperfotrate SPC against orthologous gene datasets of 12 fungal genomes. When genes were clustered by SPC type rather than species phylogeny by phylogenetic analysis from each orthologs, the genes were extracted as candidate causal genes. By using these genes, we searched SPC-type specific sites that show differences of amino acid residue depending on the difference of SPC types. We also checked whether the substitution had been derived in the exact ancestral brunch that is reasonable to assume as the period of emergence of perforate SPC by ancestral sequences reconstruction. For detecting the gene correlated with the evolution from vesiculate SPC to imperforate SPC, BLAST search against vesiculate type species was conducted to know gene present/absent pattern of detected gene. We detected spc33 as a gene correlated to the morphological evolution of SPC. Amino acid substitutions D254E, K357R, V359I and P402R were observed during morphological independent evolution from imperforate type species to perforate type species in both lineages. When we checked each sites of multiple alignment of spc33, we found K357R and M/V359I are remained such differences in extant species. Therefore, same genetic changes were detected from the independent emergence of perforate SPC. The results of BLAST search showed that spc33 was observed only from imperforate type species and perforate type species. Vesiculate type species and any other organisms did not have spc33 homologs. In conclusion, correlated evolutionary event in amino acid sequences of spc33 had been occurred during both the evolution from vesiculate SPC to imperforate SPC and the evolution from imperforate SPC to perforate SPC.
Multiple evolutionary origins lead to diversity in the metabolic profiles of ambrosia fungi
- Y. Huang
- J. Skelton
- J. Hulcr
Abstract
Abstract
Ambrosia fungi are an ecological assemblage of species cultivated by ambrosia beetles in their gallery as required nutrient sources. This nutritional mutualistic relationship with beetles has evolved at least 7 times in Dikarya (Ascomycota and Basidiomycota). However, whether convergence in ecology led to convergent metabolism in ambrosia fungi is still unknown. We compared the assimilation of 190 carbon sources in five independent lineages of ambrosia fungi and closely related, non-ambrosial species. These repeated comparisons, and the use of variation partitioning to separate the effects of phylogeny and ecology, enabled us to assess functional convergence versus phylogenetic divergence in the metabolic diversity of ambrosia fungi. Our results revealed no convergence in carbon utilization capacities among ambrosia fungi. Instead, metabolic variation among fungi was largely explained by phylogenetic relationships. In addition, the range of carbon usage was as diverse in ambrosia fungi as in non-ambrosial species. Our results demonstrate that carbon metabolism of each ambrosia fungus is determined by its inherited metabolism, rather by the transition towards symbiosis. In contrast to other fungus-farming systems of termites and attine ants, the fungal symbionts of ambrosia beetles are functionally diverse, which reflects their independent evolutionary origins.