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opencc-zeroDec 2017View details →

Data from: Horizontal partner exchange does not preclude stable mutualism in fungus-growing ants

Vertical symbiont transmission tends to stabilize mutualisms by aligning the reproductive interests of cooperating species. The attine ants conform well to this principle, because all species are nutritionally dependent on vertically transmitted and clonally propagated fungal cultivars. Multiple mechanisms expressed by both partners constrain cultivar transmission between established colonies, but these appear not to preclude horizontal transfer during colony founding, consistent with multiple phylogenetic analyses indicating at least occasional horizontal transfer. The ecological and evolutionary impact of transfers is unknown because, although they can be induced in laboratory experiments, they remain undocumented in natural colonies. In a large-scale field study, we manipulated clusters of newly founded nests and their still portable gardens in two sympatric species of Acromyrmex leaf-cutting ants. This created mosaics of intact nests, queens without a cultivar, and cultivars without a tending queen. We tracked the movements of queens and cultivars through direct observation and microsatellite analysis, respectively. This showed that horizontal acquisition of incipient gardens is surprisingly common, because queens actively searched for replacement cultivars and often adopted orphaned gardens. However, these horizontal cultivar exchanges are unlikely to destabilize obligate farming mutualisms when they are restricted to the founding stage, as colonies eventually commit to a single cultivar clone, irreversibly aligning the partners' fitness interests before colonies reproduce.

opencc-zeroDec 2013View details →

Data from: The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited

Background: We investigate the scope for selection at the level of nuclei within fungal individuals (mycelia) of the mutualistic Termitomyces cultivated by fungus-growing termites. Whereas in most basidiomycete fungi the number and kind of nuclei is strictly regulated to be two per cell, in Termitomyces mycelia the number of nuclei per cell is highly variable. We hypothesised that natural selection on these fungi not only occurs between mycelia, but also at the level of nuclei within the mycelium. We test this hypothesis using in vitro tests with five nuclear haplotypes of a Termitomyces species. Results: First, we studied the transition from a mixture of five homokaryons (mycelia with identical nuclei) each with a different nuclear haplotype to heterokaryons (mycelia with genetically different nuclei). In vitro cultivation of this mixture for multiple asexual transfers led to the formation of multiple heterokaryotic mycelia, and a reduction of mycelial diversity over time. All heterokaryotic mycelia contained exactly two types of nucleus. The success of a heterokaryon during in vitro cultivation was mainly determined by spore production and to a lesser extent mycelial growth rate. Second, heterokaryons invariably produced more spores than homokaryons implying that homokaryons will be outcompeted. Third, no homokaryotic 'escapes' from a heterokaryon via the formation of homokaryotic spores were found, despite extensive spore genotyping. Fourth, in contrast to most studied basidiomycete fungi, in Termitomyces sp. no nuclear migration occurs during mating, limiting the scope for nuclear competition within the mycelium. Conclusions: Our experiments demonstrate that in this species of Termitomyces the scope for selection at the level of the nucleus within an established mycelium is limited. Although 'mate choice' of a particular nuclear haplotype is possible during mating, we infer that selection primarily occurs between mycelia with two types of nucleus (heterokaryons).

opencc-zeroDec 2018View details →

Data from: Disease-free monoculture farming by fungus-growing termites

Fungus-growing termites engage in an obligate mutualistic relationship with Termitomyces fungi, which they maintain in monocultures on specialised fungus comb structures, without apparent problems with infectious diseases. While other fungi have been reported in the symbiosis, detailed comb fungal community analyses have been lacking. Here we use culture-dependent and -independent methods to characterise fungus comb mycobiotas from three fungus-growing termite species (two genera). Internal Transcribed Spacer (ITS) gene analyses using 454 pyrosequencing and Illumina MiSeq showed that non-Termitomyces fungi were essentially absent in fungus combs, and that Termitomyces fungal crops are maintained in monocultures as heterokaryons with two or three abundant ITS variants in a single fungal strain. To explore whether the essential absence of other fungi within fungus combs is potentially due to the production of antifungal metabolites by Termitomyces or comb bacteria, we performed in vitro assays and found that both Termitomyces and chemical extracts of fungus comb material can inhibit potential fungal antagonists. Chemical analyses of fungus comb material point to a highly complex metabolome, including compounds with the potential to play roles in mediating these contaminant-free farming conditions in the termite symbiosis.

opencc-zeroDec 2016View details →

Data from: Comparative assessment of SSR and SNP markers for inferring the population genetic structure of the common fungus Armillaria cepistipes

During the last years, simple sequence repeats (SSRs, also known as microsatellites) and single-nucleotide polymorphisms (SNPs) have become the most popular molecular markers for describing neutral genetic variation in populations of a wide range of organisms. However, only a limited number of studies has focused on comparing the performance of these two types of markers for describing the underlying genetic structure of wild populations. Moreover, none of these studies targeted fungi, the group of organisms with one of the most complex reproductive strategies. We evaluated the utility of SSRs and SNPs for inferring the neutral genetic structure of Armillaria cepistipes (basidiomycetes) at different spatial scales. For that, 407 samples were collected across a small (150 km2) area in the Ukrainian Carpathians and a large (41 000 km2) area in the Swiss Alps. All isolates were analyzed at 17 SSR loci distributed throughout the whole genome and at 24 SNP loci located in different single-copy conserved genes. The two markers showed different patterns of structure within the two spatial scales studied. The multi-allelic SSR markers seemed to be best suited for detecting genetic structure in indigenous fungal populations at a rather small spatial scale (radius of ~50-100 km). The pattern observed at SNP markers rather reflected ancient divergence of distant (~1000 km) populations that in addition are separated by mountain ranges. Despite these differences, both marker types were suitable for detecting the weak genetic structure of the two A. cepistipes populations investigated.

opencc-zeroDec 2011View details →

Data from: Recent range expansion and agricultural landscape heterogeneity have only minimal effect on the spatial genetic structure of the plant pathogenic fungus Mycosphaerella fijiensis

Understanding how geographical and environmental features affect genetic variation at both the population and individual levels is crucial in biology, especially in the case of pathogens. However, distinguishing between these factors and the effects of historical range expansion on spatial genetic structure remains challenging. In the present study, we investigated the case of Mycosphaerella fijiensis-a plant pathogenic fungus that has recently colonized an agricultural landscape characterized by the presence of potential barriers to gene flow, including several commercial plantations in which disease control practises such as the use of fungicides are applied frequently, and low host density areas. We first genotyped 300 isolates sampled at a global scale on untreated plants in 2 dimensions over a 50x80 Km area. Using two different clustering algorithms, no genetic structure was detected in the studied area, suggesting expansion of large populations and/or no influ ence of potential barriers. Second, we investigated the potential effect of disease control practises on M. fijiensis diversity by comparing populations sampled in commercial vs. food-crop plantations. At this local scale, we detected significantly higher allelic richness inside commercial plantations compared to the surrounding food-crop plantation populations. Analysis of molecular variance (AMOVA) indicated that 99% of the total genetic variance occurred within populations. We discuss the suggestion that high population size and/or high migration rate between populations might be responsible for the absence of any effect of disease control practises on genetic diversity and differentiation.

opencc-zeroDec 2013View details →

Data from: Metabolism and the rise of fungus cultivation by ants

Most ant colonies are comprised of workers that cooperate to harvest resources and feed developing larvae. Around 50 million years ago (MYA), ants of the attine lineage adopted an alternative strategy, harvesting resources used as compost to produce fungal gardens. While fungus cultivation is considered a major breakthrough in ant evolution, the associated ecological consequences remain poorly understood. Here, we compare the energetics of attine colony-farms and ancestral hunter-gatherer colonies using metabolic scaling principles within a phylogenetic context. We find two major energetic transitions. First, the earliest lower-attine farmers transitioned to lower mass-specific metabolic rates while shifting significant fractions of biomass from ant tissue to fungus gardens. Second, a transition 20 MYA to specialized cultivars in the higher-attine clade was associated with increased colony metabolism (without changes in garden fungal content) and with metabolic scaling nearly identical to hypometry observed in hunter-gatherer ants, although only the hunter-gatherer slope was distinguishable from isometry. Based on these evolutionary transitions, we propose that shifting living-tissue storage from ants to fungal mutualists provided energetic storage advantages contributing to attine diversification and outline critical assumptions that, when tested, will help link metabolism, farming efficiency, and colony fitness.

opencc-zeroDec 2012View details →

Data from: Long-term endemism of two highly divergent lineages of the amphibian-killing fungus in the Atlantic Forest of Brazil

The recent global spread of the amphibian-killing fungus [Batrachochytrium dendrobatidis (Bd)] has been closely tied to anthropogenic activities; however, regional patterns of spread are not completely understood. Using historical samples, we can test whether Bd was a spreading or endemic pathogen in a region within a particular time frame, because those two disease states provide different predictions for the regional demographic dynamics and population genetics of Bd. Testing historical patterns of pathogen prevalence and population genetics under these predictions is key to understanding the evolution and origin of Bd. Focusing on the Atlantic Forest (AF) of Brazil, we used qPCR assays to determine the presence or absence of Bd on 2799 preserved postmetamorphic anurans collected between 1894 and 2010 and used semi-nested PCRs to determine the frequency of rRNA ITS1 haplotypes from 52 samples. Our earliest date of detection was 1894. A mean prevalence of 23.9% over time and spatiotemporal patterns of Bd clusters indicate that Bd has been enzootic in the Brazilian AF with no evidence of regional spread within the last 116 years. ITS1 haplotypes confirm the long-term presence of two divergent strains of Bd (BdGPL and Bd-Brazil) and three spatiotemporally broad genetic demes within BdGPL, indicating that Bd was not introduced into southeast Brazil by the bullfrog trade. Our data show that the evolutionary history and pathogen dynamics of Bd in Brazil is better explained by the endemic pathogen hypothesis.

opencc-zeroDec 2014View details →

Data from: Plant-mycorrhizal fungus co-occurrence network lacks substantial structure

The interactions between plants and arbuscular mycorrhizal fungi (AMF) maintain a crucial link between macroscopic organisms and the soil microbial world. These interactions are of extreme importance for the diversity of plant communities and ecosystem functioning. Despite this importance, only recently has the structure of plant–AMF interaction networks been studied. These recent studies, which used genetic data, suggest that these networks are highly structured, very similar to plant–animal mutualistic networks. However, the assembly process of plant–AMF communities is still largely unknown, and an important feature of plant–AMF interactions has not been incorporated: they occur at an extremely localized scale. Studying plant–AMF networks in a spatial context seems therefore a crucial step. This paper studies a plant–AMF spatial co-occurrence network using novel methodology based on information theory and a unique set of spatially explicit species-level data. We apply three null models of which only one accounts for spatial effects. We find that the data show substantial departures from null expectations for the two non-spatial null models. However, for the null model considering spatial effects, there are few significant co-occurrences compared with the other two null models. Thus, plant–AMF spatial co-occurrences seem to be mostly explained by stochasticity, with a small role for other factors related to plant–AMF specialization. Furthermore, we find that the network is not significantly nested or modular. We conclude that this plant–AMF spatial co-occurrence network lacks substantial structure and, therefore, plants and AMF species do not track each other over space. Thus, random encounters seem more important in the first step of the assembly of plant–AMF communities.

opencc-zeroDec 2015View details →

Data from: Trade-offs in an ant–plant–fungus mutualism

Species engaged in multiple, simultaneous mutualisms are subject to trade-offs in their mutualistic investment if the traits involved in each interaction are overlapping, which can lead to conflicts and affect the longevity of these associations. We investigate this issue via a tripartite mutualism involving an ant plant, two competing ant species and a fungus the ants cultivate to build galleries under the stems of their host plant to capture insect prey. The use of the galleries represents an innovative prey capture strategy compared with the more typical strategy of foraging on leaves. However, because of a limited worker force in their colonies, the prey capture behaviour of the ants results in a trade-off between plant protection (i.e. the ants patrol the foliage and attack intruders including herbivores) and ambushing prey in the galleries, which has a cascading effect on the fitness of all of the partners. The quantification of partners' traits and effects showed that the two ant species differed in their mutualistic investment. Less investment in the galleries (i.e. in fungal cultivation) translated into more benefits for the plant in terms of less herbivory and higher growth rates and vice versa. However, the greater vegetative growth of the plants did not produce a positive fitness effect for the better mutualistic ant species in terms of colony size and production of sexuals nor was the mutualist compensated by the wider dispersal of its queens. As a consequence, although the better ant mutualist is the one that provides more benefits to its host plant, its lower host–plant exploitation does not give this ant species a competitive advantage. The local coexistence of the ant species is thus fleeting and should eventually lead to the exclusion of the less competitive species.

opencc-byFeb 2016View details →

Some kind of Fungus

Found on a cherry tree. 116 photos, Canon G7x, Agisoft PhotoScan. Source: Objaverse 1.0 / Sketchfab

FIGURE 8 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 8. Male holotype of Notolopha brachycera (Zetterstedt, 1852) sp. restit. stat. n. – A. Terminalia in ventral view. – B. Tergite IX and cerci in dorsal view. – C. Internal face of right gonostylus. – D. Dorsal lobe of gonostylus in interiofrontal view. – E. Hypandrial lobe in lateral view. Bar = 0.2 mm.

FIGURE 6 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 6. Male holotype of Exechia lucidula (Zetterstedt, 1838) – A. Terminalia in ventral view. – B. Tergite IX and cerci in dorsal view. – C. Internal face of right gonostylus, enlarged. Bars = 0.2 mm.

FIGURE 5 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 5. Male lectotype and female paralectotype of Brevicornu griseolum (Zetterstedt, 1852) sensu auct. – A. Terminalia in ventral view. – B. Tergite IX and cerci in dorsal view. – C. Internal face of right gonostylus. – D. Aedeagus in ventral view. – E. Female terminalia in lateral view. Bars = 0.2 mm.

FIGURE 4 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 4. Male holotype of Brevicornu canescens (Zetterstedt, 1852) sp. restit. stat. n. – A. Terminalia in ventral view. – B. Tergite IX and cerci in dorsal view. – C. Internal face of right gonostylus, enlarged. Bars = 0.2 mm.

FIGURE 7 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 7. Female holotype of Exechia unimaculata (Zetterstedt, 1860) – A. Terminalia dorsal view. – B. Terminalia ventral view. – C. Terminalia lateral view. Bars = 0.2 mm.

FIGURE 3 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 3. Male neotype of Allodia (Brachycampta) alternans (Zetterstedt, 1838) – A. Terminalia in ventral view. – B. Tergite IX and cerci in dorsal view. – C. Internal face of right gonostylus. Bar = 0.2 mm.

FIGURE 1 in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 1. Portrait of Johan Wilhelm Zetterstedt (1785–1874). Facsimile from Diptera Scandinaviae, volume 1 (Zetterstedt 1842).

FIGURE 2. – A in A review of fungus gnats in the tribe Exechiini (Diptera, Mycetophilidae) from the J. W. Zetterstedt collection at the Museum of Zoology in Lund, Sweden

FIGURE 2. – A. Drawer no. 62 of Zetterstedt's "Diptera Scandinaviae" collection containing most of the Exechiini specimens. – B. Example of Zetterstedt's handwritten determination labels interpreted as "M. lucidula Zett. Ψ. Lund Scan.". – C. Example of Zetterstedt's handwritten locality labels interpreted as "Winnerstad sn tagen i Charlottenborgs äng den 9 september – Oceller saknas? 72". – D. Specimen no. SPM004744. Inside this web of dust and fungal sporophores a nearly two hundred year old male of Allodia (Allodia) ornaticollis (Meigen, 1818) was found in fairly good condition. The light blue quadrangular piece of paper indicate that this specimen was collected in Skåne at Kivik´s Esperöd in Mellby parish. – E. Specimen no. SPM005154, a male Allodia (Brachycampta) grata (Meigen, 1830) in relative good condition. The light yellow piece of paper (together with a purple red piece not seen on the photo) indicate that this specimen was collected in Skåne at Björnstorp Säteri in Malmöhus län.

opennotspecifiedDec 2007View details →

FIGURE 20 in A review of the North American species of the fungus-gardening ant genus Trachymyrmex (Hymenoptera: Formicidae)

FIGURE 20: Trachymyrmex turrifex male in (a) lateral, (b) full face and (c) dorsal view. Scale bar represents 2 mm, 1 mm and 2 mm in part (a), (b) and (c), respectively.