Background: High-altitude ecosystems are extreme environments that generate specific physiological, morphological, and behavioral adaptations in ectotherms. The shifts in gut microbiota of the ectothermic hosts as an adaptation to environmental changes are still largely unknown. We investigated the food ingested and the bacterial, fungal, and protistan communities in feces of the lizardSceloporus grammicusinhabiting an altitudinal range using metabarcoding approaches.Results: The bacterial phylaBacteroidetesandFirmicutes, and the generaBacteroidesandParabacteroidesdominated the core fecal bacteriome, whileZygomycotaandAscomycota, and the speciesBasidiobolus ranarumandBasidiobolus magnusdominated the core fecal mycobiome. The diet ofS.grammicusincluded 29 invertebrate families belonging toArachnida,Chilopoda, andInsecta. The diversity and abundance of its diet decreased sharply at high altitudes, while the abundance of plant material andAgaricomyceteswas significantly higher at the highest site. The composition of the fecal microbiota ofS.grammicuswas different at the three altitudes, but not between females and males. Dietary restriction inS.grammicusat 4150 m might explain the high fecal abundance ofAkkermansiaandOscillopira, bacteria characteristic of long fasting periods, while low temperature favoredB.magnus. A high proportion of bacterial functions were digestive inS.grammicusat 2600 and 3100, while metabolism of aminoacids, vitamins, and key intermediates of metabolic pathways were higher at 4150 m. Different assemblages of fungal species in the lizard reflect differences in the environments at different elevations. Pathogens were more prevalent at high elevations than at the low ones.Conclusions: Limiting food resources at high elevations might obligeS.grammicusto exploit other food resources and its intestinal microbiota have degradative and detoxifying capacities.Sceloporus grammicusmight have acquiredB.ranarumfrom the insects infected by the fungus, but its commensal relationship might be established by the quitinolytic capacities ofB.ranarum.The mycobiome participate mainly in digestive and degradative functions while the bacteriome in digestive and metabolic functions.

We studied the effect of sustainable conservation agricultural practices versus intensive conventional ones on the soil microbial diversity, potential functionality, and community assembly in rhizosphere of maize cultivated in a semiarid environment. We found that conservation agriculture practices increased the diversity of soil microbial species and functions and strongly affected how they were structured compared to conventional practices.

Summary: Land‐use change has been identified as the most severe threat to biodiversity. Soils are important biodiversity reservoirs, but to what extent conversion of high‐altitude temperate forest to arable land affects taxonomic and functional soil biodiversity is still largely unknown. Shotgun metagenomics was used to determine the taxonomic and functional diversity of bacteria, archaea and DNA virus in terms of effective number of species in high‐altitude temperate oak and pine‐oak forest and arable soils from Mexico. Generally, the soil ecosystem maintained its microbial species richness notwithstanding land‐use change. Archaea diversity was not affected by land‐use change, but the bacterial diversity decreased with 45–55% when the oak forest was converted to arable land and 65–75% when the pine‐oak forest was. Loss in bacterial diversity as a result of land‐use change was positively correlated ( R ² = 0.41) with the 10–25% loss in functional diversity. The archaeal communities were evener than the bacterial ones, which might explain their different response to land‐use change. We expected a decrease in DNA viral communities as the bacterial diversity decreased, i.e. their potential hosts. However, a higher viral diversity was found in the arable than in the forest soils. It was found that converting high altitude oak and pine‐oak forests to arable land more than halved the bacterial diversity, but did not affect the archaeal and even increased the viral diversity.

Plant-associated microbes have specific beneficial functions and are considered key drivers for plant health. The bacterial community structure of healthy Anthurium andraeanum L. plants was studied by 16S rRNA gene pyrosequencing associated with different plant parts and the rhizosphere. A limited number of bacterial taxa, i.e., Sinorhizobium, Fimbriimonadales, and Gammaproteobacteria HTCC2089 were enriched in the A. andraeanum rhizosphere. Endophytes were more diverse in the roots than in the shoots, whereas all shoot endophytes were found in the roots. Streptomyces, Flavobacterium succinicans, and Asteroleplasma were only found in the roots, Variovorax paradoxus only in the stem, and Fimbriimonas 97%-OTUs only in the spathe, i.e., considered specialists, while Brevibacillus, Lachnospiraceae, Pseudomonas, and Pseudomonas pseudoalcaligenes were generalist and colonized all plant parts. The anaerobic diazotrophic bacteria Lachnospiraceae, Clostridium sp., and Clostridium bifermentans colonized the shoot system. Phylotypes belonging to Pseudomonas were detected in the rhizosphere and in the substrate (an equiproportional mixture of soil, cow manure, and peat), and dominated the endosphere. Pseudomonas included nine 97%-OTUs with different patterns of distribution and phylogenetic affiliations with different species. P. pseudoalcaligenes and P. putida dominated the shoots, but were also found in the roots and rhizosphere. P. fluorescens was present in all plant parts, while P. resinovorans, P. denitrificans, P. aeruginosa, and P. stutzeri were only detected in the substrate and rhizosphere. The composition of plant-associated bacterial communities is generally considered to be suitable as an indicator of plant health.