荒漠草原“土岛”生境群落物种共存机制

经过长期破碎化, 荒漠草原原生硬质灰钙土斑块散布在广大沙化土地中, 形成类似“土岛”的土被结构。为揭示土岛生境的群落物种共存机制, 2016年在宁夏盐池县皖记沟村选取大(200-300 m²)、中(约100 m²)、小(约50 m²)土岛各3个开展调查, 采用Jaccard相异系数、物种生态位宽度和生态位重叠度、零模型、Meta分析, 综合计算和分析土岛内部与外部植物群落相似性、物种生态位宽度和生态位重叠、物种共存格局及其影响因子。研究发现, (1)随着破碎化加剧, 土岛内部植物多样性整体呈现下降趋势, 群落优势种从短花针茅(Stipa breviflora)转变为猪毛蒿(Artemisia scoparia)和短花针茅共优种, 土岛内外群落相似性增加。(2)土岛内外绝大多数物种生态位重叠较小, 生态位重叠在土岛内呈集中分布, 而土岛外则呈均匀发散分布。(3)环境过滤为主的生态过程决定了土岛生境群落物种的共存格局, 随着土岛面积减小, 环境因子对群落物种共存的调控强度降低, 关键性环境因子由土壤细砂粒和黏粒转变为粗砂粒, 显著性竞争物种共存格局在小岛出现。综上所述, 土岛生境对于维持草原物种具有重要作用, 环境过滤主导了荒漠草原物种共存格局。随着生境破碎化加剧或土岛面积减小, 物种共存格局及其调控因子发生转变。保护面积在200 m²以上的大土岛对于恢复荒漠草原区草原成分种和其物种多样性机制都十分必要。     

物种概念及其界定

半世纪以来,物种概念的定义备受关注,不同研究方向的生物学家提出24种不同或至少有分歧的物种概念,根据其不同的物种概念,物种的界定和物种的数量会出现很大的差异。人们普遍认同:物种是进化分离的微居群谱系,但把谱系分离过程中获得的特征如生殖隔离、可鉴定性、单系统发生等视为鉴定物种次级特征却有不同的声音。该文提出统一的物种概念,把谱系进化分离作为物种界定的唯一而又必要的特征,把谱系分离过程中获得的次级特征作为界定谱系分离的证据。鉴于此,物种概念间的分歧就会化解。其一,物种概念化与物种界定明显分开,不再混淆;其二,谱系的次级特征只与物种界定有关,在某种程度上为谱系分离提供证据;第三,若能把合理解释的任何一个特征作为某物种客观存在的证据,这样更多的特征更能确定谱系分离;最后最重要的是,统一物种概念使我们解放思想,扬弃传统的物种界定标准,探求物种界定的新思路。     

“地衣”词考

本文考证了中国先秦时期到清末古籍中对“地衣”的解释;其中有共生学意义的“地衣”一词,是在清代李善兰的《植物学》一书中被提出的。     

“超级真菌”耳念珠菌研究进展

耳念珠菌Candida auris也被称为“超级真菌”,是近年来出现的一种人体病原真菌新物种,临床分离株通常具有多重耐药和高致死率等特征。2009年日本首次报道耳念珠菌之后,其感染病例在多个国家呈现出爆发式增长。目前已报道的病例分布在全球五大洲27个国家,包括中国。耳念珠菌感染给临床诊断和防控以及人类健康带来了巨大的挑战。本文从该菌临床分离菌株的生物学、遗传变异分化及耐药特征等方面入手,围绕分子流行病学、基因组特征、毒性因子和耐药性等方面系统地综述了近年来国内外取得的相关进展,并探讨了我国耳念珠菌感染的诊断、治疗和预防的措施。     

野生食用菌“苇菇”的物种多样性及中华美味蘑菇适生区预测

“苇菇”是主产于新疆的野生食用菌,主要分布于我国西北内陆湖泊周边的芦苇或多枝柽柳林内,埋生或半埋生在土壤中。本研究共采集和收集相关标本91份,开展了形态学和分子系统学研究,结果表明这些宏观形态特征相似的“苇菇”标本并非一个物种,而是分属于蘑菇属Bivelares组的大肥蘑菇Agaricus bitorquis、中华美味蘑菇A. sinodeliciosus和亚托柄蘑菇A. subperonatus;及Nigrobrunnescentes组的帕达纳蘑菇A. padanus。本文对“苇菇”形态进行了描述,并提供了它们的分种检索表。其中大肥蘑菇、亚托柄蘑菇和帕达纳蘑菇在我国和欧洲等地均有分布,而中华美味蘑菇仅在我国有报道。据此,依据1950-2000年生物气候数据结合中华美味蘑菇的分布实地调查结果,利用最大熵模型(maximum entropy model,MaxEnt)开展了对中华美味蘑菇分布区的分析和预测,结果表明中华美味蘑菇适生区在我国主要为新疆天山山脉南北两侧、西藏西南部、青海海西州、甘肃西北部以及内蒙古西部地区;预测国外适生区域在中亚的哈萨克斯坦和蒙古国。物种分布模型涉及的环境变量对模型的贡献率显示,最湿月降水量、最暖季度降水量、最冷季度平均温度和最暖月最高温是影响中华美味蘑菇分布的主要环境因子。研究结果表明中华美味蘑菇适生区域狭窄,为狭域种,建议应加强相关资源的保护,并积极拓展其可持续利用途径以降低对野生中华美味蘑菇子实体的过度消耗。     

新医学是解决人类健康问题的真正钥匙——需“精准”理解奥巴马的“精准医学计划”

2015年年初,美国总统奥巴马在国情咨文中提出了一个预算2.15亿美元的“精准医学计划”,希望以此“引领一个医学时代”。新闻一经发布,“精准医学”立刻成为了媒体和百姓嘴边的热词,受此影响国内亦有不少人士纷纷为美国总统的这一计划点“赞”。有人用“医学革命”来形容它,有人用“开创性”来抬高它,还有一个传闻,受奥巴马“精准医学计划”的影响,中国将在15年内投入600亿元人民币启动并发展中国版的“精准医学计划”。对此,有人提出了质疑,美国版精准医学计划是否符合中国国情?是否存在“水土不服”的可能?直接套用美国总统的智慧能否解决具有中国特色的实际问题?争论由此引发一个让人思考的问题,究竟什么才是现代医学的核心?在盲目堆钱的行动前,我们确实有必要从科学和临床应用的角度来探讨和思考一下现代医学的发展方向。 为了能“精准”地看到问题的实质,我将从当下时髦并且相关的词汇谈起,通过梳理,期待找出解决人类健康问题的真正钥匙。     

Impacts of climate warming on hybrid zone movement: Geographically diffuse and biologically porous “species borders”

Abstract The ecology and evolutionary biology of insect–plant associations has realized extensive attention, especially during the past 60 years. The classifications (categorical designations) of continuous variation in biodiversity, ranging from global patterns (e.g., latitudinal gradients in species richness/diversity and degree of herbivore feeding specialization) to localized insect–plant associations that span the biospectrum from polyphenisms, polymorphisms, biotypes, demes, host races, to cryptic species, remain academically contentious. Semantic and biosystematic (taxonomical) disagreements sometimes detract from more important ecological and evolutionary processes that drive diversification, the dynamics of gene flow and local extinctions. This review addresses several aspects of insect specialization, host‐associated divergence and ecological (including “hybrid”) speciation, with special reference to the climate warming impacts on species borders of hybridizing swallowtail butterflies (Papilionidae). Interspecific hybrid introgression may result in collapse of multi‐species communities or increase species numbers via homoploid hybrid speciation. We may see diverging, merging, or emerging genotypes across hybrid zones, all part of the ongoing processes of evolution. Molecular analyses of genetic mosaics and genomic dynamics with “divergence hitchhiking”, combined with ecological, ethological and physiological studies of “species porosity”, have already begun to unveil some answers for some important ecological/evolutionary questions. (i) How rapidly can host‐associated divergence lead to new species (and why doesn't it always do so, e.g., resulting in “incomplete” speciation)? (ii) How might “speciation genes” function, and how/where would we find them? (iii) Can oscillations from specialists to generalists and back to specialists help explain global diversity in herbivorous insects? (iv) How could recombinant interspecific hybridization lead to divergence and speciation? From ancient phytochemically defined angiosperm affiliations to recent and very local geographical mosaics, the Papilionidae (swallowtail butterflies) have provided a model for enhanced understanding of ecological patterns and evolutionary processes, including host‐associated genetic divergence, genomic mosaics, genetic hitchhiking and sex‐linked speciation genes. Apparent homoploid hybrid speciation in Papilio appears to have been catalyzed by climate warming‐induced interspecific introgression of some, but not all, species diagnostic traits, reflecting strong divergent selection (discordant), especially on the Z (= X) chromosome. Reproductive isolation of these novel recombinant hybrid genotypes appears to be accomplished via a delayed post‐diapause emergence or temporal isolation, and is perhaps aided by the thermal landscape. Changing thermal landscapes appear to have created (and may destroy) novel recombinant hybrid genotypes and hybrid species.     

The species concept as an emergent property of population biology

Resurgent interest in the genetics of population divergence and speciation coincides with recent critical evaluation of species concepts and proposals for species delimitation. An important result of these parallel trends is a slight but important conceptual shift in focus away from species diagnoses based on prior species concepts or definitions, and toward analyses of the processes acting on lineages of metapopulations that eventually lead to differences recognizable as species taxa. An advantage of this approach is that it identifies quantitative metapopulation differences in continuous variables, rather than discrete entities that do or do not conform to a prior species concept, and species taxa are recognized as an emergent property of population-level processes. The tension between species concepts and diagnosis versus emergent recognition of species taxa is at least as old as Darwin, and is unlikely to be resolved soon in favor of either view, because the products of both approaches (discrete utilitarian taxon names for species, process-based understanding of the origins of differentiated metapopulations) continue to have important applications.     

Impact of the invasive plant species “Nicotiana glauca” toxins on the larvae of the invasive insect species “Rhynchophorus ferrugineus”: A damaging pest of date palm trees in Saudi Arabia

The wild tree tobacco (Nicotiana glauca) is an alien species that invaded vast areas of the Southwestern region of Saudi Arabia. While, the Red Palm Weevil (RPW) (Rhynchophorus ferrugineus) is considered to be the most damaging invasive insect species of palm trees all over the kingdom of Saudi Arabia, causing major economic losses to farmers and the economy of the country. Using conventional insecticides to control harmful insects such as RPW has undesirable effects on the environment and human health. Alternatively, using biocontrol agents such as poisonous extracts from N. glauca might be a better approach in pest management and can be considered as an eco-friendly, cost-effective, and safe alternative. Therefore, the current study aimed to evaluate the larvicidal effect of N. glauca aqueous extracts against the red palm weevil larvae. The plant specimens were collected from Al-Baha region in the Southwest of Saudi Arabia. Each single test consisted of 20 larvae, and N. glauca preparations were; 1, 1.5, 2, 2.5, and 3 ml, besides the control test. Results obtained for the effect of botanical extracts; leaf, flower, stem and root against R. ferrugineus larvae for an exposure period of 24 hr. at the concentrations of 2.8, 4.2, 6.0, 7.0 and 8.0 ppm. The concentrations for N. glauca extracts reflected an LC₅₀ of 2.7 ppm for leave, 2.6 ppm for flower, 2.8 ppm for stem and 7.00 ppm for root. While, the same concentrations extracts reflected an LC₉₅of 11 ppm for leaf, 9.6 ppm for flower, 8.9 ppm for stem and 13.00 ppm for root. These results showed that N. glauca extracts have a remarkable potentiality as insecticidal substances that can be used as an ecofriendly integrated approach for the management of R. ferrugineus.     

Integrative species delimitation reveals cryptic diversity in the southern Appalachian Antrodiaetus unicolor (Araneae: Antrodiaetidae) species complex

Although species delimitation can be highly contentious, the development of reliable methods to accurately ascertain species boundaries is an imperative step in cataloguing and describing Earth's quickly disappearing biodiversity. Spider species delimitation remains largely based on morphological characters; however, many mygalomorph spider populations are morphologically indistinguishable from each other yet have considerable molecular divergence. The focus of our study, the Antrodiaetus unicolor species complex containing two sympatric species, exhibits this pattern of relative morphological stasis with considerable genetic divergence across its distribution. A past study using two molecular markers, COI and 28S, revealed that A. unicolor is paraphyletic with respect to A. microunicolor. To better investigate species boundaries in the complex, we implement the cohesion species concept and use multiple lines of evidence for testing genetic exchangeability and ecological interchangeability. Our integrative approach includes extensively sampling homologous loci across the genome using a RADseq approach (3RAD), assessing population structure across their geographic range using multiple genetic clustering analyses that include structure , principal components analysis and a recently developed unsupervised machine learning approach (Variational Autoencoder). We evaluate ecological similarity by using large‐scale ecological data for niche‐based distribution modelling. Based on our analyses, we conclude that this complex has at least one additional species as well as confirm species delimitations based on previous less comprehensive approaches. Our study demonstrates the efficacy of genomic‐scale data for recognizing cryptic species, suggesting that species delimitation with one data type, whether one mitochondrial gene or morphology, may underestimate true species diversity in morphologically homogenous taxa with low vagility.     

基于生物学物种定义探讨物种形成理论与验证的研究进展

物种形成是进化生物学研究的一个永恒主题, 由于生物群体进化是连续和动态的, 物种界限变得难于界定。本文首先讨论了3种地理物种形成模式(同域、邻域及异域), 并分析了近期报道的研究证据。其次, 评述了合子后生殖隔离机制的分子遗传基础和应用群体基因组数据分析的证据, 包括BDMI模型(Bateson-Dobzhansky-Muller incompatibility)、QTLs (quantitative trait loci)、霍尔丹法则及大X染色体效应。最后, 探讨了交配系统作为合子前隔离机制之一与物种形成的关系, 认为近交或自交通过扩大种群遗传结构分化, 增强不同交配系统的种群间不对称基因渐渗, 或种群间无基因渐渗等途径, 促进新物种形成。已知植物交配系统的演化更倾向于从异交(或自交不亲和)向自交(或近交亲和)方式, 花性状和基因组的分化推动形成所谓的自交综合征, 研究交配系统驱动或强化物种形成模式对认识植物物种形成机制有重要意义。