Ecology, Resource Redistribution, and Mormon Settlement in Northeastern Arizona

Successful Mormon colonization of the American West has largely been attributed to the adaptive advantage of cooperative Mormon values. This article shows that successful Mormon colonization of the Little Colorado River Basin had an ultimate ecological basis: the redistribution of surplus resources among settlements situated in dispersed and functionally independent local environments. Two systems of resource redistribution among 19th-century Little Colorado Mormon settlements are examined, showing that ecological considerations explain their differential success as adaptive mechanisms contributing to the success of this local colonization effort. The article concludes by suggesting that general ecology provides a useful theoretical framework for explaining successful Mormon colonization in this region and elsewhere.     

A quantitative life history of endangered humpback chub that spawn in the Little Colorado River: variation in movement,growth, and survival

While the ecology and evolution of partial migratory systems (defined broadly to include skip spawning) have been well studied, we are only beginning to understand how partial migratory populations are responding to ongoing environmental change. Environmental change can lead to differences in the fitness of residents and migrants, which could eventually lead to changes in the frequency of the strategies in the overall population. Here, we address questions concerning the life history of the endangered Gila cypha (humpback chub) in the regulated Colorado River and the unregulated tributary and primary spawning area, the Little Colorado River. We develop eight multistate models for the population based on three movement hypotheses, in which states are defined in terms of fish size classes and river locations. We fit these models to mark–recapture data collected in 2009–2012. We compare survival and growth estimates between the Colorado River and Little Colorado River and calculate abundances for all size classes. The best model supports the hypotheses that larger adults spawn more frequently than smaller adults, that there are residents in the spawning grounds, and that juveniles move out of the Little Colorado River in large numbers during the monsoon season (July–September). Monthly survival rates for G. cypha in the Colorado River are higher than in the Little Colorado River in all size classes; however, growth is slower. While the hypothetical life histories of life‐long residents in the Little Colorado River and partial migrants spending most of its time in the Colorado River are very different, they lead to roughly similar fitness expectations when we used expected number of spawns as a proxy. However, more research is needed because our study period covers a period of years when conditions in the Colorado River for G. cypha are likely to have been better than has been typical over the last few decades.     

Application of ecological and evolutionary theory to microbiome community dynamics across systems

A fundamental aim of microbiome research is to understand the factors that influence the assembly and stability of host-associated microbiomes, and their impact on host phenotype, ecology and evolution. However, ecological and evolutionary theories applied to predict microbiome community dynamics are largely based on macroorganisms and lack microbiome-centric hypotheses that account for unique features of the microbiome. This special feature sets out to drive advancements in the application of eco-evolutionary theory to microbiome community dynamics through the development of microbiome-specific theoretical and conceptual frameworks across plant, human and non-human animal systems. The feature comprises 11 research and review articles that address: (i) the effects of the microbiome on host phenotype, ecology and evolution; (ii) the application and development of ecological and evolutionary theories to investigate microbiome assembly, diversity and stability across broad taxonomic scales; and (iii) general principles that underlie microbiome diversity and dynamics. This cross-disciplinary synthesis of theoretical, conceptual, methodological and analytical approaches to characterizing host–microbiome ecology and evolution across systems addresses key research gaps in the field of microbiome research and highlights future research priorities.     

Water and community development in the Little Colorado River Basin

Water has historically been a critical limiting factor affecting community development throughout the American West. Within the Little Colorado River Basin of northeastern Arizona, abundant groundwater resources enabled local agricultural communities to overcome the limitations of unstable surfacewater sources. However, industrialization has led to sharp increases in groundwater consumption in the basin and to a decline in groundwater levels and/or quality at several locations. This paper examines the broader historical and regional implications of recent groundwater changes in the basin. Emphasis is placed upon the relationship between local developments and the rapid expansion of metropolitan centers in southern Arizona.     

Strong but opposing β-diversity–stability relationships in coral reef fish communities

The ‘diversity–stability hypothesis’, in which higher species diversity within biological communities buffers the risk of ecological collapse, is now generally accepted. However, empirical evidence for a relationship between β-diversity (spatial turnover in community structure) and temporal stability in community structure remains equivocal, despite important implications for theoretical ecology and conservation biology. Here, we report strong β-diversity–stability relationships across a broad sample of fish taxa on Australia''s Great Barrier Reef. These relationships were robust to random sampling error and spatial and environmental factors, such as latitude, reef size and isolation. While β-diversity was positively associated with temporal stability at the community level, the relationship was negative for some taxa, for example surgeonfishes (Acanthuridae), one of the most abundant reef fish families. This demonstrates that the β-diversity–stability relationship should not be indiscriminately assumed for all taxa, but that a species’ risk of extirpation in response to disturbance is likely to be taxon specific and trait based. By combining predictions of spatial and temporal turnover across the study area with observations in marine-protected areas, we conclude that protection alone does not necessarily confer temporal stability and that taxon-specific considerations will improve the outcome of conservation efforts.     

基于着生藻类的太子河流域水生态系统健康评价

本研究以辽宁省太子河流域为研究范例,调查了全流域范围内69个样点的着生藻类群落和水环境理化特征,并在此基础上应用硅藻生物评价指数(DBI)和生物完整性评价指数(P-IBI),同时结合栖息地环境质量评价指数(QHEI),对太子河流域水生态系统进行健康评价。结果表明,太子河流域着生藻类群落结构具有明显的空间异质性,CCA结果显示驱动着生藻类群落结构形成的水环境因子为电导率、总溶解固体和总氮。虽然DBI、P-IBI和QHEI在太子河流域某些河段上的评价结果有较大出入,但从全流域尺度上看,DBI、P-IBI和QHEI的评价结果基本一致,表现为太子河上游健康状况较好,中游健康状况一般,而下游健康状况较差。文中讨论了水环境理化因子与着生藻类群落结构的相互关系,并对比分析了DBI、P-IBI和QHEI这三种河流健康评价方法。     

Stream hierarchy defines riverscape genetics of a North American desert fish

Global climate change is apparent within the Arctic and the south‐western deserts of North America, with record drought in the latter reflected within 640 000 km² of the Colorado River Basin. To discern the manner by which natural and anthropogenic drivers have compressed Basin‐wide fish biodiversity, and to establish a baseline for future climate effects, the Stream Hierarchy Model (SHM) was employed to juxtapose fluvial topography against molecular diversities of 1092 Bluehead Sucker (Catostomus discobolus). MtDNA revealed three geomorphically defined evolutionarily significant units (ESUs): Bonneville Basin, upper Little Colorado River and the remaining Colorado River Basin. Microsatellite analyses (16 loci) reinforced distinctiveness of the Bonneville Basin and upper Little Colorado River, but subdivided the Colorado River Basin into seven management units (MUs). One represents a cline of three admixed gene pools comprising the mainstem and its lower‐gradient tributaries. Six others are not only distinct genetically but also demographically (i.e. migrants/generation <9.7%). Two of these (i.e. Grand Canyon and Canyon de Chelly) are defined by geomorphology, two others (i.e. Fremont‐Muddy and San Raphael rivers) are isolated by sharp declivities as they drop precipitously from the west slope into the mainstem Colorado/Green rivers, another represents an isolated impoundment (i.e. Ringdahl Reservoir), while the last corresponds to a recognized subspecies (i.e. Zuni River, NM). Historical legacies of endemic fishes (ESUs) and their evolutionary potential (MUs) are clearly represented in our data, yet their arbiter will be the unrelenting natural and anthropogenic water depletions that will precipitate yet another conservation conflict within this unique but arid region.     

The social and ecological consequences of early cattle ranching in the Little Colorado River Basin

Commercial cattle ranching began in east central Arizona during the late 1880s when thousands of head of cattle were introduced onto the previously unexploited grasslands of the Little Colorado River Basin. Most of these animals were imported from western Texas where serious overgrazing had resulted in both catastrophic cattle losses and widespread range deterioration. By the turn of the century, the Texas experience had been repeated in Arizona, because Texas cattlemen continued to follow the same destructive stocking practices in this new region. This paper examines: (1) the early development of cattle ranching in the Little Colorado River Basin; (2) the various factors which contributed to overgrazing in the region; and (3) the consequences that commercial cattle ranching had on the local environment and on the pre-existing farming communities of the region.     

Capturing Community Context of Human Response to Forest Disturbance by Insects: A Multi-Method Assessment

The socioeconomic and environmental features of local places (community context) influence the relationship between humans and their physical environment. In times of environmental disturbance, this community context is expected to influence human perceptual and behavioral responses. Residents from nine Colorado communities experiencing a large outbreak of mountain pine beetles (Dendroctonus ponderosae) were surveyed in 2007. Multiple analytic methods including ordinary least squares regression and multilevel modeling techniques were used to evaluate a community-context conceptual model of factors influencing individual actions in response to forest disturbance by beetles. Results indicated that community biophysical and socioeconomic characteristics had important impacts on participation in beetle-related actions and influenced the relationships of individual-level variables in the conceptual model with beetle-related activities. Our findings have implications for natural resource management and policy related to forest disturbances, and for developing a methodology appropriate to measure the general community context of human-environment interactions.     

The Relationship between Species Diversity and Genetic Structure in the Rare Picea chihuahuana Tree Species Community,Mexico

Species diversity and genetic diversity, the most basic elements of biodiversity, have long been treated as separate topics, although populations evolve within a community context. Recent studies on community genetics and ecology have suggested that genetic diversity is not completely independent of species diversity. The Mexican Picea chihuahuana Martínez is an endemic species listed as “Endangered” on the Red List. Forty populations of Chihuahua spruce have been identified. This species is often associated with tree species of eight genera in gallery forests. This rare Picea chihuahuana tree community covers an area no more than 300 ha and has been subject of several studies involving different topics such as ecology, genetic structure and climate change. The overall aim of these studies was to obtain a dataset for developing management tools to help decision makers implement preservation and conservation strategies. However, this unique forest tree community may also represent an excellent subject for helping us to understand the interplay between ecological and evolutionary processes in determining community structure and dynamics. The AFLP technique and species composition data were used together to test the hypothesis that species diversity is related to the adaptive genetic structure of some dominant tree species (Picea chihuahuana, Pinus strobiformis, Pseudotsuga menziesii and Populus tremuloides) of the Picea chihuahuana tree community at fourteen locations. The Hill numbers were used as a diversity measure. The results revealed a significant correlation between tree species diversity and genetic structure in Populus tremuloides. Because the relationship between the two levels of diversity was found to be positive for the putative adaptive AFLP detected, genetic and species structures of the tree community were possibly simultaneously adapted to a combination of ecological or environmental factors. The present findings indicate that interactions between genetic variants and species diversity may be crucial in shaping tree communities.     

环境DNA技术在地下生态学中的应用

地下生态过程是生态系统结构、功能和过程研究中最不确定的因素。由于技术和方法的限制,作为"黑箱"的地下生态系统已经成为限制生态学发展的瓶颈,也是未来生态学发展的主要方向。环境DNA技术,是指从土壤等环境样品中直接提取DNA片段,然后通过DNA测序技术来定性或定量化目标生物,以确定目标生物在生态系统中的分布及功能特征。环境DNA技术已成功用于地下生态过程的研究。目前,环境DNA技术在土壤微生物多样性及其功能方面的研究相对成熟,克服了土壤微生物研究中不能培养的问题,可以有效地分析土壤微生物的群落组成、多样性及空间分布,尤其是宏基因组学技术的发展,使得微生物生态功能方面的研究成为可能;而且,环境DNA技术已经在土壤动物生态学的研究中得到了初步应用,可快速分析土壤动物的多样性及其分布特征,更有效地鉴定出未知的或稀少的物种,鉴定土壤动物类群的幅度较宽;部分研究者通过提取分析土壤中DNA片段信息对生态系统植物多样性及植物分类进行了研究,其结果比传统的植物分类及物种多样性测定更精确,改变了以往对植物群落物种多样性模式的理解。同时,环境DNA技术克服传统根系研究方法中需要洗根、分根、只能测定单物种根系的局限,降低根系研究中细根区分的误差,并探索性地用于细根生物量的研究。主要综述了基于环境DNA技术的分子生物学方法在土壤微生物多样性及功能、土壤动物多样性、地下植物多样性及根系生态等地下生态过程研究中的应用进展。环境DNA技术对于以土壤微生物、土壤动物及地下植物根系为主体的地下生态学过程的研究具有革命性意义,并展现出良好的应用前景。可以预期,分子生物学技术与传统的生态学研究相结合将成为未来地下生态学研究的一个发展趋势。     

基于Google Earth Engine平台与复杂网络的黄河流域土地利用/覆被变化分析

黄河流域在中国社会经济发展和生态安全方面的地位十分重要,过去几十年的自然演变和人类活动对其造成了深远影响,系统科学地认识黄河流域的环境格局变化是实现黄河流域高质量发展的重要前提。基于Google Earth Engine平台和复杂网络分析方法,解译并分析了1986年至2018年黄河流域的连续年度土地利用/覆被变化(LUCC)。基于1000个独立验证点进行的评估显示解译的覆盖黄河流域33年的年度土地利用/覆被数据集的7个一级类的总体准确率为82.6%,15个二级类的总体准确率为74.7%。分析结果显示黄河流域的土地系统在整个研究期间呈现出复杂的时空变化,主要的LUCC模式包括：不变或很小的变化、伴随耕地流失的城市扩张、草地恢复、果园和梯田扩张和森林增加。基于复杂网络方法对黄河流域土地系统的分析表明,土地利用/覆被转移网络中的高覆盖草地、低植被覆盖地表和落叶常绿混交林与其他地类的转移较频繁,地类节点的中介中心性和度值较高,是黄河流域土地系统中的关键地类。另外与人类活动关系密切的果园和梯田、谷物耕地和城市及建设用地节点组成了较为活跃的网络社区结构,它们都有较高的结构多样性、接近中心性,这些地...     

基于高通量测序的乐安江冬季细菌群落特征分析

【目的】分析乐安江从上游至下游水体细菌群落结构组成变化,揭示细菌群落结构组成变化的影响因素。【方法】分析不同河段水体中C、N、P、Cu、Zn、As和Pb等化学指标。对水体DNA的16S rRNA基因进行高通量测序确定细菌群落特征。基于Bray-Curtis距离的采样点非度量多维尺度(NMDS)分析和聚类分析研究乐安江水体细菌群落结构差异,基于冗余分析(RDA)研究环境因子与细菌群落的关系。【结果】乐安江水体中C、N、P、Cu、Zn、As和Pb等化学指标含量中下游偏高。中游河水受德兴铜矿废水影响,细菌群落多样性降低,下游受农业、生活废水影响,细菌群落丰富度和多样性升高。水体中优势菌群为β-变形菌纲(Beta-proteobacteria,53.03%)、放线菌门(Actinobacteria,20.24%)和拟杆菌门(Bacteroidetes,14.75%)。中游受德兴铜矿废水影响,Beta-proteobacteria丰度增大,而Actinobacteria丰度减小;下游受微生物间捕食影响,Bacteroidetes丰度下降。在细菌群落与环境因子的关系中,DO是解释乐安江细菌群落结构变化的最佳环境因子。【结论】乐安江中游德兴铜矿废水和中下游农业、生活废水明显改变了水体细菌群落结构组成,使水体细菌群落特征从上游到下游发生显著变化。本研究为揭示人类活动对乐安江水生态环境的影响提供了参考性数据。     

Species dynamics alter community diversity–biomass stability relationships

The relationship between community diversity and biomass variability remains a crucial ecological topic, with positive, negative and neutral diversity–stability relationships reported from empirical studies. Theory highlights the relative importance of Species–Species or Species–Environment interactions in driving diversity–stability patterns. Much previous work is based on an assumption of identical (stable) species‐level dynamics. We studied ecosystem models incorporating stable, cyclic and more complex species‐level dynamics, with either linear or non‐linear density dependence, within a locally stable community framework. Species composition varies with increasing diversity, interacting with the correlation of species' environmental responses to drive either positive or negative diversity–stability patterns, which theory based on communities with only stable species‐level dynamics fails to predict. Including different dynamics points to new mechanisms that drive the full range of diversity–biomass stability relationships in empirical systems where a wider range of dynamical behaviours are important.     

河流岸带湿地沉积物重金属分布对植被物种多样性和底栖动物群落特征的影响

河流岸带湿地栖息地完整性对河流水环境、水生态和水文的安全与健康具有重要意义,为探究河流岸带湿地表层沉积物重金属分布特征及其对植被和底栖动物的影响,对滦河干流上中下游河段表层沉积物、植物群落和底栖动物调查分析,采用生物毒性效应系数法和综合潜在生态风险指数法评价沉积物重金属污染特征,采用植被物种多样性指数和底栖动物完整性指数评价滦河植物和底栖动物群落特征,探究岸带湿地沉积物重金属空间分布与植被及底栖动物群落特征之间关系。结果表明,滦河表层沉积物总体呈清洁水平,但不同河段重金属空间分布差异较大,下游重金属生态危害系数和潜在生态风险指数高于上中游。湿地物种调查共识别维管束植物219种,大型无脊椎底栖动物105种,综合评价结果表明下游植物群落物种多样性和底栖动物群落完整性低于上中游。滦河下游岸带湿地沉积物重金属对生物群落具有生物毒性和潜在的生态风险,降低了植被物种多样性和底栖动物群落完整性。大型底栖动物完整性指数能够综合反映底栖动物群落结构特征变化,对河岸带湿地生态健康评价和监测具有重要意义。     

Adaptive genetic diversity of dominant species contributes to species co-existence and community assembly

The synthesis of evolutionary biology and community ecology aims to understand how genetic variation within one species can shape community properties and how the ecological properties of a community can drive the evolution of a species. A rarely explored aspect is whether the interaction of genetic variation and community properties depends on the species'' ecological role. Here we investigated the interactions among environmental factors, species diversity, and the within-species genetic diversity of species with different ecological roles. Using high-throughput DNA sequencing, we genotyped a canopy-dominant tree species, Parashorea chinensis, and an understory-abundant species, Pittosporopsis kerrii, from fifteen plots in Xishuangbanna tropical seasonal rainforest and estimated their adaptive, neutral and total genetic diversity; we also surveyed species diversity and assayed key soil nutrients. Structural equation modelling revealed that soil nitrogen availability created an opposing effect in species diversity and adaptive genetic diversity of the canopy-dominant Pa. chinensis. The increased adaptive genetic diversity of Pa. chinensis led to greater species diversity by promoting co-existence. Increased species diversity reduced the adaptive genetic diversity of the dominant understory species, Pi. kerrii, which was promoted by the adaptive genetic diversity of the canopy-dominant Pa. chinensis. However, such relationships were absent when neutral genetic diversity or total genetic diversity were used in the model. Our results demonstrated the important ecological interaction between adaptive genetic diversity and species diversity, but the pattern of the interaction depends on the identity of the species. Our results highlight the significant ecological role of dominant species in competitive interactions and regulation of community structure.     

Environmental heterogeneity determines the ecological processes that govern bacterial metacommunity assembly in a floodplain river system

How diversity is structured has been a central goal of microbial ecology. In freshwater ecosystems, selection has been found to be the main driver shaping bacterial communities. However, its relative importance compared with other processes (dispersal, drift, diversification) may depend on spatial heterogeneity and the dispersal rates within a metacommunity. Still, a decrease in the role of selection is expected with increasing dispersal homogenization. Here, we investigate the main ecological processes modulating bacterial assembly in contrasting scenarios of environmental heterogeneity. We carried out a spatiotemporal survey in the floodplain system of the Paraná River. The bacterioplankton metacommunity was studied using both statistical inferences based on phylogenetic and taxa turnover as well as co-occurrence networks. We found that selection was the main process determining community assembly even at both extremes of environmental heterogeneity and homogeneity, challenging the general view that the strength of selection is weakened due to dispersal homogenization. The ecological processes acting on the community also determined the connectedness of bacterial networks associations. Heterogeneous selection promoted more interconnected networks increasing β-diversity. Finally, spatiotemporal heterogeneity was an important factor determining the number and identity of the most highly connected taxa in the system. Integrating all these empirical evidences, we propose a new conceptual model that elucidates how the environmental heterogeneity determines the action of the ecological processes shaping the bacterial metacommunity.Subject terms: Community ecology, Microbial ecology     

人为干扰对金马河温江段护岸林物种多样性和土壤理化性质的影响

采用典型样地法,运用干扰理论和物种多样性分析方法,使用冗余分析（RDA）研究了11个环境因子与护岸林物种多样性的关系,探究不同强度人为干扰对金马河温江段护岸林物种多样性和土壤理化性质的影响。结果表明：（1）在264个不同层次样方中,记录植物122种,隶属65科102属,其中草本层物种数量最多,种类达89种,占总记录数73%,随人为干扰强度增加物种数量逐渐减少;（2）人为干扰对金马河护岸林群落物种多样性水平产生负面影响,随着干扰强度增加,群落各层次Shannon-Wiener多样性指数（H）和物种丰富度指数（D）逐渐降低,乔木层物种组成单一,造成群落环境功能和稳定性下降;（3）群落土壤pH值呈碱性,土壤有机质含量较高,不同干扰强度下各土壤理化性质具有显著差异（P<0.05）;（4）土壤含水量、速效钾、有机质含量是影响护岸林物种多样性的最主要因子。     

Phylogenetic diversity stabilizes community biomass

Aims The relationship between biodiversity and ecological stability is a long-standing issue in ecology. Current diversity–stability studies, which have largely focused on species diversity, often report an increase in the stability of aggregate community properties with increasing species diversity. Few studies have examined the linkage between phylogenetic diversity, another important dimension of biodiversity, and stability. By taking species evolutionary history into account, phylogenetic diversity may better capture the diversity of traits and niches of species in a community than species diversity and better relate to temporal stability. In this study, we investigated whether phylogenetic diversity could affect temporal stability of community biomass independent of species diversity.Methods We performed an experiment in laboratory microcosms with a pool of 12 bacterivorous ciliated protist species. To eliminate the possibility of species diversity effects confounding with phylogenetic diversity effects, we assembled communities that had the same number of species but varied in the level of phylogenetic diversity. Weekly disturbance, in the form of short-term temperature shock, was imposed on each microcosm and species abundances were monitored over time. We examined the relationship between temporal stability of community biomass and phylogenetic diversity and evaluated the role of several stabilizing mechanisms for explaining the influence of phylogenetic diversity on temporal stability.Important findings Our results showed that increasing phylogenetic diversity promoted temporal stability of community biomass. Both total community biomass and summed variances showed a U-shaped relationship with phylogenetic diversity, driven by the presence of large, competitively superior species that attained large biomass and high temporal variation in their biomass in both low and high phylogenetic diversity communities. Communities without these species showed patterns consistent with the reduced strength of competition and increasingly asynchronous species responses to environmental changes under higher phylogenetic diversity, two mechanisms that can drive positive diversity–stability relationships. These results support the utility of species phylogenetic knowledge for predicting ecosystem functions and their stability.     

伊洛河流域草本植物群落物种多样性

生物多样性沿环境梯度的变化是生物多样性研究的重要内容,环境梯度包含了多种环境因子(海拔高度、水热条件、人类扰动等)的综合。以伊洛河流域草本植物群落为对象,沿河从入黄河口到河源地选取典型样地调查研究伊洛河流域草本植物群落物种多样性及其分布格局。结果表明:物种丰富度和Shannon-Wiener多样性指数沿河均稍呈"S"型曲线变化,不同群落类型中分布格局差别不大,各群落类型中的物种丰富度和多样性均呈现出中游丘陵山地交界区最高,上游河源区次之,下游平原地区最低的趋势;β多样性指数的变化趋势与α多样性较一致,总体上呈现出中游丘陵山地区物种更替速率较快,平原区更替较慢;在流域内上游河源地属于自然植被区,人为干扰较轻,具有较高的物种多样性,物种替代主要受物种的竞争扩散能力和生境条件的制约;在下游平原农业区,人类活动强烈,区域内以人工生态系统为主,物种组成简单,物种替代具有跳跃性的特征,主要受人类活动的制约;在中游从自然生态系统向农业生态系统的过渡区域,人类活动的扰动有一定的强度,导致该区域内自然分布种和伴人种混合生长,具有较高的物种多样性和较快的物种替代速率。总体上伊洛河流域草本植物群落物种多样性分布格局强烈的受到人类活动的影响,物种替代速率较高。