Ecological memory and relocation decisions in fungal mycelial networks: responses to quantity and location of new resources

Saprotrophic cord-forming basidiomycetes, with their mycelial networks at the soil/litter interface on the forest floor, play a major role in wood decomposition and nutrient cycling/relocation. Many studies have investigated foraging behaviour of their mycelium, but there is little information on their intelligence. Here, we investigate the effects of relative size of inoculum wood and new wood resource (bait) on the decision of a mycelium to remain in, or migrate from, inoculum to bait using Phanerochaete velutina as a model. Experiments allowed mycelium to grow from an inoculum across the surface of a soil microcosm where it encountered a new wood bait. After colonisation of the bait, the original inoculum was moved to a tray of fresh soil to determine whether the fungus was still able to grow out. This also allowed us to test the mycelium’s memory of growth direction. When inocula were transferred to new soil, there was regrowth from 67% of the inocula, and a threshold bait size acted as a cue for the mycelium’s decision to migrate for a final time, rather than a threshold of relative size of inoculum: bait. There was greater regrowth from the side that originally faced the new bait, implying memory of growth direction

Armed and dangerous - chemical warfare in wood decay communities

Fungal community structure and development in decaying woody resources are largely dependent on interspecific antagonistic interactions that determine the distribution of territory – and hence the nutrients within – between different individuals occupying that resource. Interactions are mediated by antagonistic mechanisms, which determine the combative outcome: either deadlock, where neither mycelium loses any territory, or replacement, where one mycelium displaces the other. These mechanisms function aggressively and/or defensively, and include changes in primary metabolism and growth, as well as secondary metabolite production and stress mitigation responses. This chemical warfare may occur as a constitutive defence through modification of the territory occupied by an individual, and the deposition of antimicrobial compounds within. Following detection of a competitor, the metabolite and enzymic profile of a mycelium alters both qualitatively and quantitatively, and different mechanisms may be stimulated when confronted with different competitors. Biotic and abiotic factors, even small alterations, can affect the deployment of these antagonistic mechanisms, altering the general hierarchy of combative ability between species and making it impossible to predict outcomes with certainty. Here we explore recent advances in our understanding of combative interactions between wood decayers, and explain why future research priorities involving the application of emerging biochemical and molecular technologies must focus on interactions in more ecologically realistic and meaningful scenarios

Making hollow trees: inoculating living trees with wood-decay fungi for the conservation of threatened taxa - a guide for conservationists

Decaying wood and cavities in living trees are fundamental determinants of forest biodiversity. However, a long history of forestry and land-use change has created a fragmented network of woodland with a depleted stock of veteran trees that support these microhabitats. Decomposition is a slow process and it may take heart-rot fungi hundreds of years to establish before hollowing even begins. A major challenge to forest restoration, therefore, is how these habitats can be restored or replicated. One approach is to inoculate trees with heart-rot fungi as a direct intervention to accelerate tree hollowing. We identify two types of conservation inoculation that could be beneficial in forest conservation: (1) Veteranising inoculations designed to benefit cavity and decay dependant fauna; and (2) Translocation inoculations, to reintroduce locally extinct, dispersal-limited heart-rot fungi. Tree inoculations have a hundred-year pedigree but successes have been mixed and there are no long-term published studies. Reflecting on previous heart-rot inoculations we discuss elements of the inoculation protocol to aid design of conservation inoculations. Conservation inoculations have the potential to be a useful tool in forest restoration and we hope to stimulate wider uptake as a direct method for conservation

New approaches to investigating the function of mycelial networks

Fungi play a key role in ecosystem nutrient cycles by scavenging, concentrating, translocating and redistributing nitrogen. To quantify and predict fungal nitrogen redistribution, and assess the importance of the integrity of fungal networks in soil for ecosystem function, we need better understanding of the structures and processes involved. Until recently nitrogen translocation has been experimentally intractable owing to the lack of a suitable radioisotope tracer for nitrogen, and the impossibility of observing nitrogen translocation in real time under realistic conditions. We have developed an imaging method for recording the magnitude and direction of amino acid flow through the whole mycelial network as it captures, assimilates and channels its carbon and nitrogen resources, while growing in realistically heterogeneous soil microcosms. Computer analysis and modeling, based on these digitized video records, can reveal patterns in transport that suggest experimentally testable hypotheses. Experimental approaches that we are developing include genomics and stable isotope NMR to investigate where in the system nitrogen compounds are being acquired and stored, and where they are mobilized for transport or broken down. The results are elucidating the interplay between environment, metabolism, and the development and function of transport networks as mycelium forages in soil. The highly adapted and selected foraging networks of fungi may illuminate fundamental principles applicable to other supply networks

Weight status associations with physical activity intensity and physical self-perceptions in 10-to 11-year-old children

The study examined associations between children&rsquo;s weight status, physical activity intensity, and physical self-perceptions. Data were obtained from 409 children (224 girls) aged 10&ndash;11 years categorized as normal-weight or overweight/obese. Physical activity was assessed using accelerometry, and children completed the Physical Self-Perception Profile. After controlling for the effects of age, maturation, and socioeconomic status vigorous physical activity was significantly associated with normal-weight status among boys (OR = 1.13, p = .01) and girls (OR = 1.13, p = .03). Normal-weight status was significantly associated with perceived Physical Condition (Boys: OR = 5.05, p = .008; Girls: OR = 2.50, p = .08), and Body Attractiveness (Boys: OR = 4.44, p = .007; Girls: OR = 2.56, p = .02). Weight status of 10&ndash;11 year old children was significantly associated with time spent in vigorous physical activity and self-perceptions of Body Attractiveness and Physical Condition.<br /

Further evidence for fungivory in the Lower Devonian (Lochkovian) of the Welsh Borderland, UK

The recent demonstrations that widespread mid-Palaeozoic Prototaxites and other nematophytes had fungal affinities indicate that terrestrial fungi were important elements in carbon cycling in the Early Devonian. Here, we provide evidence for their participation in the recycling of nutrients by early terrestrial invertebrates. Evidence is in the form of coprolites, both those associated with nematophytes or containing their fragmentary remains. Cylindrical coprolites consistently associated with fungal mats are placed in a new ichnospecies, Bacillafaex myceliorum. Their contents are granular to amorphous, suggestive of complete digestion of the ingested hyphae, with the inference of possession of chitinases in the digestive tracts of the consumers. A further single example comprises a cluster of cylindrical bodies attached to the lower surface of a Nematothallus fragment. Here, homogenisation was less complete, with traces of hyphae remaining. Terrestrial animal fossils have not been found at the locality, but scorpions, pseudoscorpions, Opiliones, mites, centipedes (carnivores) and millipedes, and Collembola (detritivores) have been recorded from the slightly younger Rhynie cherts. Studies of fungivory in extant arthropods have concentrated on Collembola and, to a lesser extent, mites, but their faecal pellets are much smaller than the fossil examples. Millipedes, based on body size and faeces of extant forms, are considered more realistic producers, but little is known about fungal feeding in these animals. Regardless of the affinities of the producers, the diversity in morphology, sizes, aggregations, and composition of nematophyte-containing examples suggests that fungivory was an important component of carbon cycling in early terrestrial ecosystems

Bacteria in decomposing wood and their interactions with wood-decay fungi

The fungal community within dead wood has received considerable study, but far less attention has been paid to bacteria in the same habitat. Bacteria have long been known to inhabit decomposing wood, but much remains underexplored about their identity and ecology. Bacteria within the dead wood environment must interact with wood-decay fungi, but again, very little is known about the form this takes; there are indications of both antagonistic and beneficial interactions within this fungal microbiome. Fungi are hypothesised to play an important role in shaping bacterial communities in wood, and conversely, bacteria may affect wood-decay fungi in a variety of ways. This minireview considers what is currently known about bacteria in wood and their interactions with fungi, and proposes possible associations based on examples from other habitats. It aims to identify key knowledge gaps and pressing questions for future research

Biological maturity and primary school children\u27s physical activity : influence of different physical activity assessment instruments

Biological maturation may attenuate hypothesized sex differences in children&rsquo;s physical activity but overall the evidence for this is equivocal. In this study, we investigated how the selection of different physical activity assessment instruments affects the detected relationship between biological maturation and late primary school children&rsquo;s physical activity. Altogether, 175 children (97 girls, 78 boys) aged 10.690.3 years completed the PAQ-C self-report questionnaire and wore ActiGraph GT1M accelerometers for 5 consecutive days. Maturity status was predicted by estimating attainment of age at peak height velocity. Following initial exploration of sex differences in PAQ-C (t-test) and multiple ActiGraph outcome variables (MANOVA), the influence of maturity status was controlled using ANCOVA and MANCOVA. Unadjusted analyses revealed that boys were significantly more active than girls according to the PAQ-C (PB0.0001, d0.52) and ActiGraph (PB0.0001, d0.360.72). After controlling for maturity status, the differences in PAQ-C scores increased (P0.001, d0.64), but the significant differences disappeared for the ActiGraph data (P0.36, d0.170.33). The detected relationship between maturity status and late primary school children&rsquo;s physical activity is dependent on the physical activity assessment tool employed, reflecting the different aspects of physical activity captured by the respective measures.<br /

Incorporating alternative interaction modes, forbidden links and trait‐based mechanisms increases the minimum trait dimensionality of ecological networks

1. Individual-level traits mediate interaction outcomes and community structure. It is important, therefore, to identify the minimum number of traits that characterise ecological networks, that is, their ‘minimum dimensionality’. Existing methods for estimating minimum dimensionality often lack three features associated with in- creased trait numbers: alternative interaction modes (e.g. feeding strategies such as active vs. sit-and-wait feeding), trait-mediated ‘forbidden links’ and a mechanistic description of interactions. Omitting these features can underestimate the trait numbers involved, and therefore, minimum dimensionality. We develop a ‘mini- mum mechanistic dimensionality’ measure, accounting for these three features.2. The only input our method requires is the network of interaction outcomes. We assume how traits are mechanistically involved in alternative interaction modes. These unidentified traits are contrasted using pairwise performance inequalities between interacting species. For example, if a predator feeds upon a prey spe- cies via a typical predation mode, in each step of the predation sequence, the predator's performance must be greater than the prey's. We construct a system of inequalities from all observed outcomes, which we attempt to solve with mixed integer linear programming. The number of traits required for a feasible system of inequalities provides our minimum dimensionality estimate.3. We applied our method to 658 published empirical ecological networks includ- ing primary consumption, predator–prey, parasitism, pollination, seed dispersal and animal dominance networks, to compare with minimum dimensionality estimates when the three focal features are missing. Minimum dimensionality was typically higher when including alternative interaction modes (54% of empirical networks), ‘forbidden interactions’ as trait-mediated interaction outcomes (92%) or a mechanistic perspective (81%), compared to estimates missing these features. Additionally, we tested minimum dimensionality estimates on simulated networks with known dimensionality. Our method typically estimated a higher minimum dimensionality, closer to the actual dimensionality, while avoiding the overestimation associated with a previous method.4. Our method can reduce the risk of omitting traits involved in different interaction modes, in failure outcomes or mechanistically. More accurate estimates will allow us to parameterise models of theoretical networks with more realistic structure at the interaction outcome level. Thus, we hope our method can improve predictions of community structure and structure-dependent dynamics