Abstract Aim Sexual systems strongly influence angiosperm evolution and play important roles in community assembly and species responses to climate change. However, geographical variation in proportions of different sexual systems (dioecy, monoecy and hermaphroditism) in response to changes in climate, life-history traits and evolutionary age remains poorly understood. Here, we map the geographical variation in proportions of different sexual systems and hypothesize that the prevalence of hermaphrodites increases with aridity owing to their advantages in colonizing harsh environments, whereas dioecy is most successful in humid regions with tall-canopy vegetation and old floras. Location China. Time period Current. Major taxa studied Woody angiosperms. Methods Using data on sexual systems and distributions of 10,449 woody species in China, we estimated the proportions of different sexual systems in local floras (50 km × 50 km grid cells). Spatial linear models, phylogenetic general linear models and structural equation models were used to compare the relative influences of climate, plant height and evolutionary age on geographical variation in proportions of different sexual systems. Results We found contrasting geographical patterns in the proportions of different sexual systems. The proportions of dioecy and monoecy increased with plant height and were highest in humid regions with older floras, whereas that of hermaphroditism decreased with plant height and was highest in arid regions with younger floras. Plant height was the strongest correlate of sexual system frequency. Climate influenced sexual system frequency both directly and indirectly via its effects on plant height. Main conclusions Our study provides the first continuous map of sexual system composition in woody floras over a large spatial scale. Our findings suggest that mature plant height, reflecting plant longevity, dominates geographical variation in sexual systems and that the proportions of different sexual systems in local floras might reflect their correlated evolution with traits in response to climate changes.
We investigated whether fine-grained coordination in a screen-based puzzle task with a (virtual) partner would influence on-line perspective-taking. Participants played a screen-based puzzle game with a computer player. In the high-coordination condition, the player presented participants with puzzle pieces that could be placed near their partner’s last piece. In the low-coordination condition, pieces could only be placed further away from their partner’s last piece. Participant’s eye movements were then measured in a referential communication task, with the partner giving the instructions, and whether possible competitor referents were in shared or privileged ground. The results demonstrate clear effects of ground and coordination. Participants in both coordination groups were sensitive to the perspective of the interlocutor. In addition, participants in the high-level coordination condition were more sensitive to statistical regularities in the input and their comprehension was more time-locked to the utterance of the speaker.
Crude oil could affect certain critical microbial processes of nitrogen cycling (N-cycling) in coastal sediments, and disturb the nitrogen balance. However, the understanding of the effects of crude oil on coastal sediments N-cycling under human disturbance was still limited. In this study, two sediments (named SY and HB with heavy and slight pollution, respectively) were sampled from Hangzhou Bay, China. After an incubation with exposure to different amounts of crude oil in above two sediments for 30 days, we found that crude oil affected microbial N-cycling in multiple levels. Potential rate measurements revealed that crude oil stimulated potential denitrification and N2O emissions in both sediments, which showed a higher influence on denitrification rates in higher concentration of oil. Quantitative PCR revealed that crude oil greatly increased abundances of bacterial and archaeal 16S rRNA genes and N-cycling genes (nirS, nosZ, nrfA, part of AOA and AOB amoA). On the other hand, only a few genes (16S rRNA and nrfA) showed higher transcriptional activities in oil-addition treatments. Results about relative changes of N-cycling genes revealed that the variations of N-cycling genes in oil-addition treatments were related to sediment types but not crude oil concentrations, and the genes in HB were more sensitive to crude oil than SY. Network analysis of N-cycling genes found that crude oil decreased the complexity of N-cycling gene networks in SY, while increased complexity in HB, and led to more competition among N-cycling microbes. Our findings help to look into the effects of crude oil on key N-cycling processes, and improve the understanding of the interactions among N-cycling under crude oil contamination.
Bioaugmentation is an effective technology for treating wastewater containing recalcitrant organic pollutants. However, it is restricted by several technical problems, including the difficult colonization and survival of the inoculated bacteria, and the time-consuming start-up process. Considering the important roles of quorum sensing (QS) in regulating microbial behaviors, this study investigated the effects of N-acyl-homoserine lactones (AHLs)-based manipulation on the start-up of biofilm reactors bioaugmented with a pyridine-degrading strain Paracoccus sp. BW001. The results showed that, in the presence of two specific exogenous AHLs (C6-HSL and 3OC6-HSL), the biofilm formation process on carriers was significantly accelerated, producing thick and structured biofilms. The protein and polysaccharide contents of the extracellular polymeric substances (EPS) and soluble microbial products (SMP) in sludge were also elevated, possibly due to the increased abundance of several EPS-producing bacterial genera. Specifically, the stability and complexity of protein structures were improved. Besides the reactor running time, the AHL-manipulation was proved to be the main factor that drove the shift of bacterial community structures in the reactors. The addition of exogenous AHLs significantly increased the succession rate of bacterial communities and decreased the bacterial alpha diversity. Most importantly, the final proportions of the inoculated strain BW001 were elevated by nearly 100% in both sludge and biofilm communities via the AHL-manipulation. These findings strongly elucidated that AHL-based QS was deeply involved in biofilm formation, sludge characteristics, and microbial community construction in bioaugmented reactors, providing a promising start-up strategy for bioaugmentation technology.