Search for: All records

Abstract Predators can alter the movement of nutrients through ecosystems by depositing waste products following predation. Whilst the benefits of predator waste for large predators (e.g. bears) or dense accumulations of predators (e.g. seabirds on islands) seem clear, less is known about whether smaller, solitary predators can have measurable effects on local ecosystem processes.In separate experiments with web‐building and wandering spiders, we tested if the presence of predators affected soil nutrient content, soil respiration, soil microbial communities, and plant growth.In the first experiment with black widow spiders, total nitrogen and nitrate were not affected by spider presence, but ammonia and phosphorus were higher from soil under the edge of the spider web than soil away from the spider. Soil respiration and plant growth were both higher in soil collected from under the spider retreat compared with soil collected away from the spider web.In a second experiment with wolf spiders, we tested for interactions between spiders and soil microbial communities. There were positive effects of wolf spider presence on all soil nutrients and there were interactions between spiders and soil type (i.e. field‐collected versus autoclaved) for total carbon, total nitrogen, nitrate, and pH. Spider presence and soil type also affected soil respiration and spider presence had a large effect on the composition of the microbial community of the soil. There were also positive effects of wolf spider presence on plant biomass and plant height, with a significant interaction between spiders and soil type for plant height.Overall, our results show that two spiders with different life histories (i.e. web‐building and wandering) both have significant positive effects on plant growth through the deposition of their waste products. These effects may occur through the direct deposition of nutrients and changes in soil microbial communities. Although, further work is needed to resolve these interactions. Read the freePlain Language Summaryfor this article on the Journal blog. 

Abstract Establishment of microbial communities in neonatal calves is vital for their growth and overall health. While this process has received considerable attention for bacteria, our knowledge on temporal progression of anaerobic gut fungi (AGF) in calves is lacking. Here, we examined AGF communities in faecal samples from six dairy cattle collected at 24 different time points during the pre‐weaning (days 1–48), weaning (days 48–60), and post‐weaning (days 60–360) phases. Quantitative polymerase chain reaction indicated that AGF colonisation occurs within 24 h after birth, with loads slowly increasing during pre‐weaning and weaning, then drastically increasing post‐weaning. Culture‐independent amplicon surveys identified higher alpha diversity during pre‐weaning/weaning, compared to post‐weaning. AGF community structure underwent a drastic shift post‐weaning, from a community enriched in genera commonly encountered in hindgut fermenters to one enriched in genera commonly encountered in adult ruminants.Comparison of AGF community between calves day 1 post‐birth and their mothers suggest a major role for maternal transmission, with additional input from cohabitating subjects. This distinct pattern of AGF progression could best be understood in‐light of their narrower niche preferences, metabolic specialisation, and physiological optima compared to bacteria, hence eliciting a unique response to changes in feeding pattern and associated structural GIT development during maturation. 

Summary We report on the genomic characterization of three novel classes in the phylum Desulfobacterota. One class (proposed nameCandidatus‘Anaeroferrophillalia’) was characterized by heterotrophic growth capacity, either fermentatively or utilizing polysulfide, tetrathionate or thiosulfate as electron acceptors. In the absence of organic carbon sources, autotrophic growth via the Wood–Ljungdahl (WL) pathway and using hydrogen or Fe(II) as an electron donor is also inferred for members of the ‘Anaeroferrophillalia’. The second class (proposed nameCandidatus‘Anaeropigmentia’) was characterized by its capacity for growth at low oxygen concentration, and the capacity to synthesize the methyl/alkyl carrier CoM, an ability that is prevalent in the archaeal but rare in the bacterial domain. Pigmentation is inferred from the capacity for carotenoid (lycopene) production. The third class (proposed nameCandidatus‘Zymogenia’) was characterized by fermentative heterotrophic growth capacity, broad substrate range and the adaptation of some of its members to hypersaline habitats. Analysis of the distribution pattern of all three classes showed their occurrence as rare community members in multiple habitats, with preferences for anaerobic terrestrial, freshwater and marine environments over oxygenated (e.g. pelagic ocean and agricultural land) settings. Special preference for some members of the classCandidatus‘Zymogenia’ for hypersaline environments such as hypersaline microbial mats and lagoons was observed.