Environmental Adaptation Strategies Research Articles

Scarce water resources and priority irrigation schemes from agronomic crops

Global environmental change places unavoidable pressure on water resources and agronomic crop production systems. Irrigation development is a credible measure to alleviate the challenge of food safety under water shortages, but it needs sufficient basis. The aim of this study is to address the problem of balancing water scarcity with food requirements, which are the key components of water security in regions with population growth. Marginal water productivity (MWP) indices for irrigation water performance and productivity evaluation were established in the current study. Based on the analysis of the regional water-crop relationship and spatial differences of MWP in China, the priorities for developing irrigation areas in different types of regions are discussed in this study. The results show that high MWPs are mainly in semi-arid regions with precipitation (P) between 500 and 1000 mm, while low MWPs mostly occur in areas with P more than 1000 and less than 500 mm. The significance and spatial distribution patterns of MWP are different than those of conventional irrigation water use efficiency evaluation indices, so its role cannot be replaced for the real production capacity of irrigation water evaluation. The strategies for global environmental change adaptation suggested in this study are taking MWP for irrigation water productivity evaluation and the priority irrigation schemes for agronomic crop determination; increasing MWP by means of irrigation efficiency and crop variety improvement worldwide; and raising global food production through the expansion of irrigation area in the regions hold high MWP and abundant water resources.

Comparing perceived effects of climate-related environmental change and adaptation strategies for the Pacific small island states of Tuvalu, Samoa, and Tonga

Inhabitants of Pacific small island states are facing multiple socio-ecological pressures, with climate change being one of the most prominent. Nevertheless, the agency of local stakeholders in decisions on how to adapt to climate-related environmental change has been largely underappreciated in the climate change sciences as well as in policy decisions. We, therefore, conducted a survey study in Tuvalu, Samoa, and Tonga, asking specifically how residents perceive their situation regarding climate-related challenges, what adaptation strategies they have devised and implemented, and what they expect of governmental and nongovernmental organisations in these efforts. In contrast to the common perception that Pacific small island states are primarily threatened by rising sea levels, residents’ perceptions indicate that drought, cyclones and other flood-related problems pose a far more imminent danger. Our results suggest that further research on those perceived environmental changes is advisable to provide reliable data for scientific models and policy decisions.

Comparative genomic analysis reveals the evolution and environmental adaptation strategies of vibrios

BackgroundVibrios are among the most diverse and ecologically important marine bacteria, which have evolved many characteristics and lifestyles to occupy various niches. The relationship between genome features and environmental adaptation strategies is an essential part for understanding the ecological functions of vibrios in the marine system. The advent of complete genome sequencing technology has provided an important method of examining the genetic characteristics of vibrios on the genomic level.ResultsTwo Vibrio genomes were sequenced and found to occupy many unique orthologues families which absent from the previously genes pool of the complete genomes of vibrios. Comparative genomics analysis found vibrios encompass a steady core-genome and tremendous pan-genome with substantial gene gain and horizontal gene transfer events in the evolutionary history. Evolutionary analysis based on the core-genome tree suggested that V. fischeri emerged ~ 385 million years ago, along with the occurrence of cephalopods and the flourish of fish. The relatively large genomes, the high number of 16S rRNA gene copies, and the presence of R-M systems and CRISPR system help vibrios live in various marine environments. Chitin-degrading related genes are carried in nearly all the Vibrio genomes. The number of chitinase genes in vibrios has been extremely expanded compared to which in the most recent ancestor of the genus. The chitinase A genes were estimated to have evolved along with the genus, and have undergone significant purifying selective force to conserve the ancestral state.ConclusionsVibrios have experienced extremely genome expansion events during their evolutionary history, allowing them to develop various functions to spread globally. Despite their close phylogenetic relationships, vibrios were found to have a tremendous pan-genome with a steady core-genome, which indicates the highly plastic genome of the genus. Additionally, the existence of various chitin-degrading related genes and the expansion of chitinase A in the genus demonstrate the importance of the chitin utilization for vibrios. Defensive systems in the Vibrio genomes may protect them from the invasion of external DNA. These genomic features investigated here provide a better knowledge of how the evolutionary process has forged Vibrio genomes to occupy various niches.

Unravelling the Identity, Metabolic Potential and Global Biogeography of the Atmospheric Methane-Oxidizing Upland Soil Cluster α.

SummaryUnderstanding of global methane sources and sinks is a prerequisite for the design of strategies to counteract global warming. Microbial methane oxidation in soils represents the largest biological sink for atmospheric methane. However, still very little is known about the identity, metabolic properties and distribution of the microbial group proposed to be responsible for most of this uptake, the uncultivated upland soil cluster α (USCα). Here, we reconstructed a draft genome of USCα from a combination of targeted cell sorting and metagenomes from forest soil, providing the first insights into its metabolic potential and environmental adaptation strategies. The 16S rRNA gene sequence recovered was distinctive and suggests this crucial group as a new genus within the Beijerinckiaceae, close to Methylocapsa. Application of a fluorescently labelled suicide substrate for the particulate methane monooxygenase enzyme (pMMO) coupled to 16S rRNA fluorescence in situ hybridisation (FISH) allowed for the first time a direct link of the high‐affinity activity of methane oxidation to USCα cells in situ. Analysis of the global biogeography of this group further revealed its presence in previously unrecognized habitats, such as subterranean and volcanic biofilm environments, indicating a potential role of these environments in the biological sink for atmospheric methane.

内陆盐沼芦苇根系形态及生物量分配对土壤盐分因子的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 内陆盐沼芦苇根系形态及生物量分配对土壤盐分因子的响应 DOI: 10.5846/stxb201707141283 作者: 作者单位: 西北师范大学地理与环境科学学院，甘肃省湿地资源保护与产业发展工程研究中心,西北师范大学地理与环境科学学院，甘肃省湿地资源保护与产业发展工程研究中心,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41461013，91125014）；甘肃省生态学重点学科基金项目资助 Response of root morphology and biomass of Phragmites australis to soil salinity in inland salt marsh Author: Affiliation: Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根系形态和生物量分配是决定根系吸收能力发挥的重要特征，其对环境限制因子的响应与适应策略一直是研究的热点。然而，有关土壤盐分对植物根系性状的影响还存在许多不确定性。选择兰州秦王川国家湿地公园芦苇群落为研究对象，垂直于沙河河岸从湿地边缘至湿地中心，依次设置3个不同土壤盐分梯度样地（样地I、样地Ⅱ和样地Ⅲ），采用全根挖掘法和Win-RHIZO根系分析仪相结合的方法，研究了芦苇（Phragmites australis）根冠比、根总长度、比根长、根分叉数、根平均直径等形态参数的变化特征。结果表明：随着样地土壤盐分含量的增加，湿地群落的高度、盖度、密度、地上生物量逐渐下降，芦苇的根冠比、根分叉数呈逐渐减小的趋势，比根长、根总长度呈先下降后上升的趋势，而根平均直径呈相反的变化趋势；研究区土壤含盐量总体以中度盐渍化为主，表层土壤盐分呈现强变异性，随土层深度的增加含盐量呈下降趋势，而变异程度有所差异；芦苇根系性状与土壤含盐量的相关性分析可知，土壤含盐量与根总长度和比根长呈极显著相关关系（P < 0.01），与根冠比、根分叉数呈显著相关（P < 0.05），而与根平均直径相关性不显著。内陆盐沼的芦苇表现出敏感植物的特性，通过根系形态的调整和生物量分配策略的改变来适应盐分强变异的土壤环境，体现了逆境胁迫下湿地植物应对多重环境选择压力的生态适应机制。 Abstract:Root morphology and biomass allocation are important features for determining the capacity of root absorption, and the nature of the responses to environmental constraint factors and adaptation strategies have been a hot research topic. However, numerous uncertainties about the effects of soil salinity on the root traits of plants still exist. This study was performed on Phragmites australis community in Qinwangchuan National Wetland Park of Lanzhou. Three different plots with a soil salinity gradient (plot I, Ⅱ, and Ⅲ) were set up from the edge to the center of wetland, which was perpendicular to the bank of the Sha River. The change characteristics of the morphological parameters such as the ratio of root to shoot, total and specific root lengths, root forks, and the average root diameter of P. australis were studied using the combined method of total root excavation along with the Win-RHIZO root analyzer. The results showed that the height, coverage, density, and above-ground biomass of the wetland community decreased gradually with the increase of soil salinity. In addition, the ratio of root to shoot and root forks of P. australis decreased gradually, and the specific and total root lengths of P. australis first decreased and then they subsequently increased whereas the average root diameter showed an opposite trend. The soil salinity was dominated by moderate salinization, and the surface soil salinity showed strong variability. Specifically, the soil salinity of the plots showed a decreasing trend with increasing soil depth, and the variation degree was different. According to the correlation analysis, there was a significant correlation between the soil salinity, total root length, and specific root length (P < 0.01). Furthermore, the soil salinity was significantly correlated with the root/shoot ratio and root forks (P < 0.05), but not the root mean diameter. The P. australis specimens in the inland salt marshes showed the characteristics of sensitive plants. They adapted to the soil environment that had a strong salt variation by modifying their root morphology and changing the biomass allocation strategy. This phenomenon reflected the ecological adaptation mechanism used by wetland plants to cope with multiple environmental selection pressures under adverse stress conditions. 参考文献 相似文献 引证文献

Foliar carbon, nitrogen, and phosphorus stoichiometry in a grassland ecosystem along the Chinese Grassland Transect

Carbon (C), nitrogen (N), and phosphorus (P) are the basic nutrient elements required for plant growth and function. Ecological stoichiometry provides an important method for the determination of plant nutrient utilization and the environmental adaptation strategies of plants. Studying the stoichiometry of C, N and P is crucial to the understanding of nutrient cycling and ecosystem stabilization mechanisms. Most studies so far have focused only on N and P stoichiometry for plant leaves and ignored the stoichiometry characteristics among C, N, and P. As a major element of plant dry matter, C, along with critical nutrient elements (N and P) could regulate and influence the consumption and fixation of organic matter in ecosystems. Therefore, it is necessary to study the ecological stoichiometry of C, N, and P in plants. Here, C, N and P concentrations and their ratios were measured for 329 foliar samples collected at 132 sites along the 4500km-long Chinese Grassland Transect (CGT) that traverses the Inner Mongolian and Qinghai-Tibet Plateaus. The content of C, N, and P of plant leaves in grassland ranged from 257.40 to 590.77mg/g, 4.49 to 45.85mg/g, and 0.20 to 3.40mg/g, with an average of 463.76mg/g, 19.94mg/g, 1.31mg/g, respectively. The coefficient of variation (CV) of P was highest (0.47) while the CV values of C and N were 0.09 and 0.34, respectively. N and P were positively correlated (R2=0.491, P<0.0001), in agreement with previous studies, while no significant correlation was found between C and P or between C and N. The ranges for C/N, N/P, and C/P were 10.93–93.67 (with an average of 26.86 and a CV value of 0.46) for C/N, 1.68–53.00 (with an average of 16.59 and a CV value of 0.39) for N/P, and 61.49–1995.24 (with an average of 436.77 and a CV value of 0.59) for C/P, respectively. The mass ratio of C:N:P in grassland plant was 440:17:1, and the atom ratio was 1136:43:1. C/N and C/P, C/N and N/P were positively correlated (R2=0.509, P<0.0001; R2=0.410, P<0.0001, respectively), while C/N and N/P were not significantly correlated. C concentrations of grassland plant in the Chinese Grassland Transect were close to those at the global scale, but lower than that in forests in China. N and P concentrations in grassland plant were lower than those in global terrestrial plants, while N concentrations were much higher but P concentrations were much lower than those in forest plants. C/N and C/P were relatively higher, reflecting the higher vegetative utilization efficiency of grassland vegetation. The CV of P was much higher and the N/P in this study was higher than 16, which indicated that grassland plants in China are more restricted by P elements. Our results could help to understand the relationship between C, N, and P stoichiometry in grassland plants and provide basic data for related ecological models.

Deciphering emerging Zika and dengue viral epidemics: Implications for global maternal-child health burden.

SummarySince its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vectors (Aedes mosquitoes) in Latin America in the 1950s, an absolute neglect of Zika programs and interventions has been documented in Aedes endemic and epidemic-prone countries. The current unprecedented Zika viral epidemics and rapid spread in the Western hemisphere pose a substantial global threat, with associated anxiety and consequences. The lack of safe and effective drugs and vaccines against Zika or dengue epidemics further buttresses the realization from the West Africa Ebola outbreak that most emerging disease-prone countries are still poorly prepared for an emergency response. This paper examines knowledge gaps in both emerging and neglected arthropod-borne flavivirus infectious diseases associated with poverty and their implications for fostering local, national and regional emerging disease preparedness, effective and robust surveillance–response systems, sustained control and eventual elimination. Strengthening the regional and Global Health Flavivirus Surveillance-Response Network (GHFV-SRN) with other models of socio-economic, climatic, environmental and ecological mitigation and adaptation strategies will be necessary to improve evidence-based national and global maternal–child health agenda and action plans.

Simulating cultivar variations in potato yields for contrasting environments

Potato (Solanum tuberosum L.) is a major food commodity becoming increasingly important for food security, especially in the developing world. The rising demand for potatoes combined with yield gaps and potential adverse impacts from climate change call for strategies for yield improvement and environmental adaptation. Crop growth models can help identify and assess such strategies. In this study, the SUBSTOR potato model was used in a systematic assessment of all cultivar parameters in the model in a range of environments including temperate, subtropical, and tropical regions to identify options for future crop improvement and to develop strategies for climate change adaptation in potato production. Our results show that yield responses to changes in cultivar parameters are specific to the environment. Some changes are less effective in subtropical and tropical environments and more effective in increasing yields in temperate environments. Solar radiation, day length, and temperature are the environmental factors that constrain the effectiveness of cultivar parameters in changing yields. The simulated variation in yields among environments was larger than the variation from changes in cultivar parameters. The impact of cultivar parameter changes on yield also varied with the cultivar parameter. The potential tuber growth rate was the cultivar parameter with the strongest effect on yields. Changes in the potential tuber growth rate parameter can lead to large yield changes in tropical highlands and temperate environments that have high solar radiation to ensure sufficient assimilate production for a larger sink. Results also suggest that improving crop management (e.g., N input) is more important for increasing yields than the potential in cultivar improvement. The study showed that crop modeling can help assess alternative strategies of yield improvement and support targeting and prioritization of efforts to improve crop productivity across different environments, based on an improved understanding of genotype by environment by management interactions. Results also showed how crop models can yield insights relevant for climate change adaptation even when only using weather data of the current climate.

Trapping toxins within lipid droplets is a resistance mechanism in fungi.

Lipid droplets (LDs) act as intracellular storage organelles in most types of cells and are principally involved in energy homeostasis and lipid metabolism. However, the role of LDs in resistance to toxins in fungi remains largely unknown. Here, we show that the trapping of endogenous toxins by LDs is a self-resistance mechanism in the toxin producer, while absorbing external lipophilic toxins is a resistance mechanism in the toxin recipient that acts to quench the production of reactive oxygen species. We found that an endolichenic fungus that generates phototoxic perylenequinones (PQs) trapped the PQs inside LDs. Using a model that incorporates the fungicidal action of hypocrellin A (HA), a PQ derivative, we showed that yeast cells escaped killing by trapping toxins inside LDs. Furthermore, LD-deficient mutants were hypersusceptible to HA-mediated phototoxins and other fungicides. Our study identified a previously unrecognised function of LDs in fungi that has implications for our understanding of environmental adaptation strategies for fungi and antifungal drug discovery.

Hot n’ Cold: Molecular Signatures of Domestication Bring Fresh Insights into Environmental Adaptation

Recent investigations of divergent rice genotypes have identified previously unknown molecular adaptations conferring heat and chilling tolerance in their corresponding local environments (Figure 1). These studies shed new light both on the domestication of rice and environmental adaptation strategies.

Draft genome sequences of 10 strains of the genus exiguobacterium.

High-quality draft genome sequences were determined for 10 Exiguobacterium strains in order to provide insight into their evolutionary strategies for speciation and environmental adaptation. The selected genomes include psychrotrophic and thermophilic species from a range of habitats, which will allow for a comparison of metabolic pathways and stress response genes.

Molecular interactions within the halophilic, thermophilic, and mesophilic prokaryotic ribosomal complexes: clues to environmental adaptation

Using the available crystal structures of 50S ribosomal subunits from three prokaryotic species: Escherichia coli (mesophilic), Thermus thermophilus (thermophilic), and Haloarcula marismortui (halophilic), we have analyzed different structural features of ribosomal RNAs (rRNAs), proteins, and of their interfaces. We have correlated these structural features with the environmental adaptation strategies of the corresponding species. While dense intra-rRNA packing is observed in thermophilic, loose intra-rRNA packing is observed in halophilic (both compared to mesophilic). Interestingly, protein–rRNA interfaces of both the extremophiles are densely packed compared to that of the mesophilic. The intersubunit bridge regions are almost devoid of cavities, probably ensuring the proper formation of each bridge (by not allowing any loosely packed region nearby). During rRNA binding, the ribosomal proteins experience some structural transitions. Here, we have analyzed the intrinsically disordered and ordered regions of the ribosomal proteins, which are subjected to such transitions. The intrinsically disordered and disorder-to-order transition sites of the thermophilic and mesophilic ribosomal proteins are simultaneously (i) highly conserved and (ii) slowly evolving compared to rest of the protein structure. Although high conservation is observed at such sites of halophilic ribosomal proteins, but slow rate of evolution is absent. Such differences between thermophilic, mesophilic, and halophilic can be explained from their environmental adaptation strategy. Interestingly, a universal biophysical principle evident by a linear relationship between the free energy of interface formation, interface area, and structural changes of r-proteins during assembly is always maintained, irrespective of the environmental conditions.

Factors affecting whether environmental migration is temporary or permanent: Evidence from Bangladesh

This study examines whether environmental migrants in Bangladesh move permanently or temporarily. The analyses are based on data collected in 2010 and 2011, and cover four themes, namely migrant characteristics, environmental change related factors, conflict and adaptation strategies, and social networks. The estimates obtained from binary logit models show that most sets of variables have statistically significant impacts on the temporary migration versus permanent migration decision. Females are more inclined to migrate temporarily, a finding which is consistent with prior studies that argued that female migration is one temporary household survival strategy in the face of an environmental crisis. The probability of intending to move temporarily is significantly affected by the prior occupational experience: Migrants who were previously engaged in agriculture or fishing are more inclined to migrate permanently. Those households who reported that they had lost assets due to environmental hazards are shown to have a higher probability of becoming permanent migrants. In contrast, loss of livestock and crop failure are associated with a greater likelihood of temporary migration. The empirical results reveal the groups that can be targeted in destination regions in settlement policy, and equally the groups whose return home can be facilitated once any immediate danger has passed.

Comparative transcriptomics in threeMethylophilaceaespecies uncover different strategies for environmental adaptation

We carried out whole transcriptome analysis of three species of Methylophilaceae, Methylotenera mobilis, Methylotenera versatilis and Methylovorus glucosotrophus, in order to determine which metabolic pathways are actively transcribed in cultures grown in laboratory on C1 substrates and how metabolism changes under semi-in situ conditions. Comparative analyses of the transcriptomes were used to probe the metabolic strategies utilized by each of the organisms in the environment. Our analysis of transcript abundance data focused on changes in expression of methylotrophy metabolic modules, as well as on identifying any functional modules with pronounced response to in situ conditions compared to a limited set of laboratory conditions, highlighting their potential role in environmental adaptation. We demonstrate that transcriptional responses to environmental conditions involved both methylotrophy and non-methylotrophy metabolic modules as well as modules responsible for functions not directly connected to central metabolism. Our results further highlight the importance of XoxF enzymes that were previously demonstrated to be highly expressed in situ and proposed to be involved in metabolism of methanol by Methylophilaceae. At the same time, it appears that different species employ different homologous Xox systems as major metabolic modules. This study also reinforces prior observations of the apparent importance of the methylcitric acid cycle in the Methylotenera species and its role in environmental adaptation. High transcription from the respective gene clusters and pronounced response to in situ conditions, along with the reverse expression pattern for the ribulose monophosphate pathway that is the major pathway for carbon assimilation in laboratory conditions suggest that a switch in central metabolism of Methylotenera takes place in response to in situ conditions. The nature of the metabolite(s) processed via this pathway still remains unknown. Of the functions not related to central metabolism, flagellum and fimbria synthesis functions appeared to be of significance for environmental adaptation, based on their high abundance and differential expression. Our data demonstrate that, besides shared strategies, the organisms employed in this study also utilize strategies unique to each species, suggesting that the genomic divergence plays a role in environmental adaptation.

Understanding subarctic wildlife in Eastern James Bay under changing climatic and socio-environmental conditions: bringing together Cree hunters' ecological knowledge and scientific observations

The Canadian Subarctic is undergoing climatic and environmental changes which are leading to wide-ranging implications for wildlife, ecosystems and aboriginal communities. Through their long-term experience and observations, Cree hunters of the Eastern James Bay are aware of the local manifestations of changes to animal ecology. This article presents and analyses Cree observations of the effects of altering climatic and environmental conditions on animals and their habitat. Cree Trappers Association (CTA) members are witnessing the appearance of pioneer species, changes in animal population trends, migration patterns and distribution, animal behavior, health and habitat which in turn has impacted Cree traditional subsistence activities. Their observations have the potential to fill gaps in wildlife research for subarctic Canada and could serve to influence culturally appropriate environmental change adaptation strategies. The climate change application in the GeoPortal of Eeyou Istchee – a community-based geospatial information tool developed by the CTA to record climate observations and changes in ecosystem is presented in this article denoting the engagement of the Cree in subarctic research. This article contrasts Cree hunters' observation with scientific knowledge and identifies challenges and areas of convergence between scientific and indigenous expertise for investigating animal ecology under a changing climate in the Subarctic.

岷江干旱河谷25种植物一年生植株根系功能性状及相互关系

相同条件下相同生长期的植物根系生长与适应策略及其差异性还不清楚。因此,采集岷江干旱河谷地区25种乡土植物(木本15/草本10种)的种子于2009年3月播种在同一干旱环境中,9月测定了1年生植株的最大根深(RD_max)、根幅(RW)与根生物量(RB),计算了总根长(TRL)、比根长(SRL)及细/粗根生物量比(RB_f/c),分析了它们之间的关系,进行了根系功能组划分。结果表明:1) 25种植物1年生植株RD_max与RW变异较小,总变异率为14.9%和20.7%;TRL和SRL变异相对较大,分别为28.5%和34.7%,草本植物SRL明显大于木本植物;RB和RB_f/c种间变异较大,总变异率分别为50.1%和70.5%;2) 25种植物的RD_max、RW、RB和TRL间呈显著正相关关系,表明根系较深的物种RW较大,TRL和RB也较高;SRL与RD_max呈极显著负相关关系,与RB_f/c呈极显著正相关关系,表明根系垂直分布较浅的物种细根发达,SRL较大;3) 主成分分析显示,25种植物可分为3个功能组:第1组具有较大RD_max、RW和RB,资源利用持续时间较长;第2组具有较大TRL、SRL和RB_f/c,资源利用效率较高;第3组根系功能性状没有一致的突出特点,可能通过降低自身生理机能适应生存条件。综合分析表明,岷江干旱河谷区25种植物1年生植株根系的功能性状变异明显,可塑性大,历经长期自然选择压力而形成了不同的环境适应策略,但生长型并不必然表达出1年生植株根系功能性状的差异性。;The functional traits and distribution patterns of roots affect the amount of soil resources used by the plant. These functional traits can mirror plant ecological resource utilization strategies for capturing soil water and nutrients. Changes in root functional traits can affect important plant processes, including water- and nutrient-use efficiencies and the ability to compete for belowground resources. In this study, root functional traits and correlations among them were investigated in one-year-old plants of 25 species from the arid valley of Minjiang River. The specific objectives were to compare plants of the same age growing in the same conditions to assess the trade-offs among root functions based on correlations among different functional traits, and to define plant functional types and their adaptation strategies. Seeds of vascular plant species were pretreated and sown in March 2009 in a field at the Maoxian Station for Ecosystem Research, Chinese Academy of Science. Complete root systems were sampled by excavating the entire individual in September, 2009, when plants were one year old. We measured six root functional traits; root depth_max, root width, total root length, specific root length, total root biomass, and ratio of fine/coarse root biomass. We examined the specific ecological strategies of the 25 species in adapting to the same habitat by comparing and contrasting the individual trait range and testing relationships among root functional traits. There was relatively low variability among the 25 species in terms of root depth_max (14.9%) and root width (20.7%), but higher variability in total root length (28.5%) and specific root length (34.7%). The specific root length of herbaceous plants was markedly greater than that of woody plants. Among the 25 species, there were significant differences in root biomass (total variance ratio, 50.1%) and the ratio of fine/coarse root biomass (total variance ratio, 70.5%). At the species level, there were significant positive correlations among root depth_max, root width, total root length, and root biomass, indicating that plants with deeper roots generated greater root width, longer total root length, and greater root biomass. In addition, specific root length was significantly positively correlated with the ratio of fine/coarse root biomass but negatively correlated with root depth_max. These results indicated that plants with higher specific root length tended to generate more fine roots but a relatively shallow root system. The principal component analysis showed that the 25 species could be divided into three functional groups, explaining nearly 80% of the total variation. The first group had larger root depth_max, greater root width, and greater root biomass; the second group had greater total root length, greater specific root length, and larger ratio of fine/coarse root biomass; the third group did not show uniform patterns for any of the six functional traits. This comprehensive analysis revealed that there was variability in the individual root functional traits among 25 different species from the arid valley of Minjiang River, and that different functional types showed various environmental adaptation strategies. Species adapt to local water and nutrient conditions either by improving water- and nutrient-use efficiencies or by decreasing root performance functions. The life-form of a given species could not predict differences in functional root traits at the one-year-old growth stage.

Evolutionary origins of Brassicaceae specific genes in Arabidopsis thaliana

BackgroundAll sequenced genomes contain a proportion of lineage-specific genes, which exhibit no sequence similarity to any genes outside the lineage. Despite their prevalence, the origins and functions of most lineage-specific genes remain largely unknown. As more genomes are sequenced opportunities for understanding evolutionary origins and functions of lineage-specific genes are increasing.ResultsThis study provides a comprehensive analysis of the origins of lineage-specific genes (LSGs) in Arabidopsis thaliana that are restricted to the Brassicaceae family. In this study, lineage-specific genes within the nuclear (1761 genes) and mitochondrial (28 genes) genomes are identified. The evolutionary origins of two thirds of the lineage-specific genes within the Arabidopsis thaliana genome are also identified. Almost a quarter of lineage-specific genes originate from non-lineage-specific paralogs, while the origins of ~10% of lineage-specific genes are partly derived from DNA exapted from transposable elements (twice the proportion observed for non-lineage-specific genes). Lineage-specific genes are also enriched in genes that have overlapping CDS, which is consistent with such novel genes arising from overprinting. Over half of the subset of the 958 lineage-specific genes found only in Arabidopsis thaliana have alignments to intergenic regions in Arabidopsis lyrata, consistent with either de novo origination or differential gene loss and retention, with both evolutionary scenarios explaining the lineage-specific status of these genes. A smaller number of lineage-specific genes with an incomplete open reading frame across different Arabidopsis thaliana accessions are further identified as accession-specific genes, most likely of recent origin in Arabidopsis thaliana. Putative de novo origination for two of the Arabidopsis thaliana-only genes is identified via additional sequencing across accessions of Arabidopsis thaliana and closely related sister species lineages. We demonstrate that lineage-specific genes have high tissue specificity and low expression levels across multiple tissues and developmental stages. Finally, stress responsiveness is identified as a distinct feature of Brassicaceae-specific genes; where these LSGs are enriched for genes responsive to a wide range of abiotic stresses.ConclusionImproving our understanding of the origins of lineage-specific genes is key to gaining insights regarding how novel genes can arise and acquire functionality in different lineages. This study comprehensively identifies all of the Brassicaceae-specific genes in Arabidopsis thaliana and identifies how the majority of such lineage-specific genes have arisen. The analysis allows the relative importance (and prevalence) of different evolutionary routes to the genesis of novel ORFs within lineages to be assessed. Insights regarding the functional roles of lineage-specific genes are further advanced through identification of enrichment for stress responsiveness in lineage-specific genes, highlighting their likely importance for environmental adaptation strategies.

When mobility makes sense: A qualitative and longitudinal study of the daily mobility of the elderly

A majority of North Americans hopes to grow old in the suburbs. This aspiration depends upon their ability to drive and their access to a car. Because it is essential for everyday travel, car-mobility in the suburbs is becoming a symbolic goal. The meanings of mobility for elderly will evolve over time, notably as a result of changes in autonomy. However, the mobility of older adults is mainly understood in terms of daily trips. Little research has considered the temporal dimension of aging as an evolving process. This study aimed at understanding with a qualitative and longitudinal perspective how older people stay (auto-)mobile in their house and their neighborhood against the need to adapt to reduced autonomy and mobility over time. A group of 22 suburbanites aged from 62 to 89 was interviewed in 1999 and in 2006. The results show that even if older people succeed in increasing their mobility, they are headed for inevitable immobility. Among the environmental adaptation strategies that were observed, the constructed behaviors, the dependencies demanding additional supports as well as the social life modulate different evolving experiences of the city: the shrinking city, the fragmented city, and the city by proxy. The built environment is at the heart of a complex process in which the adaptation of mobility contributes to the emergence of new residential experiences.