The contrasting effects of fluctuating temperature on bacterial diversity and performances in temperate and subtropical soils.

The extremely high species diversity of soil bacterial community has fascinated and puzzled community ecologists. Although theory predicts that fluctuations in environments can facilitate diversity maintenance, the effects of fluctuating temperature on species diversity have rarely been investigated in species-rich microbial communities. Here, we examined whether fluctuating temperature had positive effects on species diversity relative to constant temperatures in soil bacterial communities, and investigated the effects of fluctuating temperature on bacterial performances (changes in relative abundance).

Antibiotics Drive Expansion of Rare Pathogens in a Chronic Infection Microbiome Model.

Chronic (long-lasting) infections are globally a major and rising cause of morbidity and mortality. Unlike typical acute infections, chronic infections are ecologically diverse, characterized by the presence of a polymicrobial mix of opportunistic pathogens and human-associated commensals. To address the challenge of chronic infection microbiomes, we focus on a particularly well-characterized disease, cystic fibrosis (CF), where polymicrobial lung infections persist for decades despite frequent exposure to antibiotics.

Microbial biogeography of acid mine drainage sediments at a regional scale across southern China.

Investigations of microbial biogeography in extreme environments provide unique opportunities to disentangle the roles of environment and space in microbial community assembly. Here, we reported a comprehensive microbial biogeographic survey of 90 acid mine drainage (AMD) sediment samples from 18 mining sites of various mineral types across southern China. We found that environmental selection was strong in determining the AMD habitat species pool.

Seasonal Climate Variations Promote Bacterial α-Diversity in Soil.

Ecological theory suggests that temporal environmental fluctuations can contribute greatly to diversity maintenance. Given bacteria's short generation time and rapid responses to environmental change, seasonal climate fluctuations are very likely to play an important role in maintaining the extremely high α-diversity of soil bacterial community, which has been unfortunately neglected in previous studies. Here, with in-depth analyses of two previously published soil bacterial datasets at global scale, we found that soil bacterial α-diversity was positively correlated with both seasonal variations of temperature and precipitation.

Microbiome Data Enhances Predictive Models of Lung Function in People With Cystic Fibrosis.

Background: Microbiome sequencing has brought increasing attention to the polymicrobial context of chronic infections. However, clinical microbiology continues to focus on canonical human pathogens, which may overlook informative, but nonpathogenic, biomarkers. We address this disconnect in lung infections in people with cystic fibrosis (CF).

Local biotic interactions drive species-specific divergence in soil bacterial communities.

It is well accepted that environmental heterogeneity and dispersal are key factors determining soil bacterial community composition, yet little is known about the role of local biotic interactions. Here we address this issue with an abundance-manipulation experiment that was conducted in a semiarid grassland. We manually increased the abundance of six randomly chosen resident bacterial species in separate, closed, communities and allowed the communities to recover in situ for 1 year.

Stability of A Coevolving Host-parasite System Peaks at Intermediate Productivity.

Habitat productivity may affect the stability of consumer-resource systems, through both ecological and evolutionary mechanisms. We hypothesize that coevolving consumer-resource systems show more stable dynamics at intermediate resource availability, while very low-level resource supply cannot support sufficiently large populations of resource and consumer species to avoid stochastic extinction, and extremely resource-rich environments may promote escalatory arms-race-like coevolution that can cause strong fluctuations in species abundance and even extinction of one or both trophic levels. We tested these ideas by carrying out an experimental evolution study with a model bacterium-phage system (Pseudomonas fluorescens SBW25 and its phage SBW25Φ2).

Evolutionary rescue can be impeded by temporary environmental amelioration.

Rapid evolutionary adaptation has the potential to rescue from extinction populations experiencing environmental changes. Little is known, however, about the impact of short-term environmental fluctuations during long-term environmental deterioration, an intrinsic property of realistic environmental changes. Temporary environmental amelioration arising from such fluctuations could either facilitate evolutionary rescue by allowing population recovery (a positive demographic effect) or impede it by relaxing selection for beneficial mutations required for future survival (a negative population genetic effect).

Field experimental evidence that stochastic processes predominate in the initial assembly of bacterial communities.

To assess the relative importance of environmental selection, dispersal and stochastic processes in structuring ecological communities, we conducted a bacterial community assembly experiment using microcosms filled with sterile liquid medium under field conditions in the Inner Mongolian grasslands. Multiple replicate microcosms containing different carbon substrates were placed at nine locations across three spatial scales (10, 300 and 10 000 m distance between locations) in such a way that the environment of microcosms varies independently of the geographical distance. The operational taxonomic units within the experimental communities were assessed via the terminal restriction fragment length polymorphism techniques on the 10th and 17th days after the onset of the experiment.

The role of late-acting self-incompatibility and early-acting inbreeding depression in governing female fertility in monkshood, Aconitum kusnezoffii.

Reduced seed yields following self-pollination have repeatedly been observed, but the underlying mechanisms remain elusive when self-pollen tubes can readily grow into ovaries, because pre-, post-zygotic late-acting self-incompatibility (LSI), or early-acting inbreeding depression (ID) can induce self-sterility. The main objective of this study was to differentiate these processes in Aconitum kusnezoffii, a plant lacking stigmatic or stylar inhibition of self-pollination. We performed a hand-pollination experiment in a natural population of A.