Molecular phylogeny and diversity of penaeid shrimps (Crustacea: Decapoda) from South-East Asian waters

The decapod family Penaeidae comprises most of the economically important marine shrimp species. Its members are widespread throughout the world, with its highest species diversity centred in the Indo-West Pacific region. Despite this importance, their taxonomy, classification and phylogeny are not yet settled due in part to incongruence among hypotheses proposed from molecular versus morphological studies. In this study, using a thorough taxonomic sampling of especially the South-East Asian species, we aim to (a) utilize a reconstructed phylogeny to test the monophyly of the Penaeidae and its currently recognized genera and (b) explore its species diversity in South-East Asian waters. To infer the phylogeny, a combined gene data set (including 109 ingroup and six outgroup taxa) of mitochondrial genes, COI and 16S rRNA, and two nuclear genes, NaK and PEPCK, was utilized. To explore its diversity, another data set that included 371 COI gene sequences (231 newly generated and 140 retrieved from public sources) was compiled and subsequently analysed with two different tools (ABGD and bPTP) for species delimitation. Other than supporting the non-monophyly of the Penaeidae with the Sicyoniidae nested within the penaeid tribe Trachypenaeini, the genera Penaeus, Mierspenaeopsis and Parapenaeopsis were also revealed to be polyphyletic. Our species delimitation analysis inferred that 94 putative species actually existed within the 71 morphospecies reviewed, indicating an underestimated biodiversity in this family and the potential presence of new species within the following morphospecies: Kishinouyepenaeopsis cornuta, K. incisa, Mierspenaeopsis sculptilis, M hardwicki, Parapenaeopsis coromandelica and Penaeus monodon.     

福廷瓶头霉与马尾松的共生特征

深色有隔内生真菌（dark septate endophyte,DSE）广泛定殖于植物根系,对促进植物生长、提高植物抗逆能力具重要作用。本研究从马尾松Pinus massoniana根系分离到一株DSE,于无菌条件下研究了此菌与马尾松的共生特征,研究结果表明：基于形态学和分子生物学分析,此菌被鉴定为福廷瓶头霉Phialocephala fortinii,在PDA培养基25℃培养条件下,此菌不产孢,菌丝深色、具隔,最适培养基为PDA。此菌与马尾松根系共生体的形成过程可划分为3个时期,即侵入前期：接种后2d,新生菌丝向马尾松根系定向生长并开始接触根系,但未侵入根系内部;侵入期：接种后4d,菌丝与马尾松根系接触侵入根内并在根系皮层细胞间扩展延伸;形成期：接种后6d,菌丝继续在马尾松根系内扩展并形成富含脂类物质的微菌核。接种福廷瓶头霉显著增加了马尾松生物量的积累（P<0.05）,并影响了其根系发育。接种后,马尾松主根生长受限,侧根生长显著提高（P<0.05）,侧根长度较未接种处理增加了112.87%。被侵染根系的根毛数量减少,并由大量根外菌丝包裹。以上结果对进一步揭示DSE与宿主的共生机理有一定指导意义。     

对新型冠状病毒肺炎继发真菌感染的思考

新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)疫情十分严重,给民众的健康带来了巨大威胁。COVID-19患者可能继发侵袭性真菌感染,会严重威胁患者的生命,因此,在诊治策略上应该给予重视。除了加强高危患者中病原真菌的常规检查外,还应加大力度支持和扶持病原真菌先进检测技术的研发;此外,还应重点支持针对医疗单位、公共场所和家庭等常温环境以及体表和器物表面灭活病毒、细菌、真菌等病原体的新型技术和方法的研发。最终为国家战胜COVID-19和继发感染疫情提供新措施和新策略。     

Variation in the methods leads to variation in the interpretation of biodiversity–ecosystem multifunctionality relationships

生物多样性常常和生态系统多功能性(生态系统同时提供多个生态系统功能的能力)正相关。然而,生物多样性与生态系统多功能性的关系是否依赖于生态系统功能的数目有诸多争议。其中,生物多样性对生态系统多功能性的影响或许不随生态系统功能数目的变化而变化,或者随生态系统功能数目的增多而增强。我们期望通过研究不同生态系统多功能性指数的统计原理来解决这些争议。 我们使用了模型模拟和一系列来自不同空间尺度(从局域到全球)和不同生物群系(温带和高寒草地、森林和干旱地)的经验数据。我们回顾了量化生态系统多功能性的三种方法,包括平均值法、加和法和阈值法。我们发现随着生态系统功能数目的增加,生物多样性与生态系统多功能性的关系要么不变,要么增强。这些结果可由平均和加和的多功能性指数的统计原理来解释。具体来讲,当利用生态系统功能的平均值计算多功能性指数时,由于多样性对多功能性的效应等于多样性对单个生态系统功能效应的平均值,所以不会随生态系统功能数目的变化而变化。同样的道理,当利用单个生态系统的加和值计算多功能性指数时,多样性的效应会随着生态系统功能数目的增加而增强。我们提出了一个改进的多功能性指数,将平均或加和多功能性指数转化为标准化的多功能性指数, 以便于对不同研究的结果进行比较。此外,我们提出了基于变量数值范围的标准化方法来解决阈值法的数学假象问题(多样性效应随生态系统功能数目的增加而增强)。我们的研究结果表明,量化多功能性指数的方法不同,结果也不同。因此,有必要加深对不同方法数理基础的理解。而标准化的多功能性指数为比较不同研究中的生物多样性与生态系统多功能性的关系提供了有效的方法。     

小叶锦鸡儿天然居群叶形态性状变异研究

为揭示小叶锦鸡儿(Caragana microphylla)天然居群叶形态性状的变异规律及其生态适应性特征,该研究以10个小叶锦鸡儿天然居群为对象,通过多重比较、巢式方差分析、相关性分析、聚类分析和主成分分析等方法,对7个叶形态性状进行分析。结果表明：(1)小叶锦鸡儿叶形态性状在居群内和居群间均存在极显著差异(P < 0.01),平均变异系数为10.13%,不同性状的变异幅度为6.23%~12.78%;平均叶形态性状的表型分化系数为43.62%,居群内变异(30.09%)大于居群间变异(24.91%),说明居群内是其叶形态性状变异的主要来源。(2)相关性分析表明,环境因子对小叶锦鸡儿的叶形态性状变异有很大的影响,在地理空间上主要呈现出沿海拔梯度的变异模式;主成分分析的结果显示,小叶宽、叶柄宽和叶柄长对小叶锦鸡儿叶形态变异起主导作用;利用欧式距离对小叶锦鸡儿居群进行UPGMA聚类分析结果显示,基于叶形态性状和环境因子可分别将小叶锦鸡儿10个居群分为3类和2类,Mantel检验结果表明,小叶锦鸡儿的叶形态性状变异不存在地理连续性。研究结果为小叶锦鸡儿的适应性进化和开发利用提供了理论依据。     

遮荫处理对芍药幼苗生长和矿质营养积累的影响

遮荫是保护芍药幼苗生长的重要措施。本试验研究了不同遮荫处理对多伦芍药幼苗生长特性和矿质营养积累的影响,以便为多伦芍药幼苗栽培提供指导。采用盆栽试验,研究不遮荫(CK)、出苗一周后20%遮荫、40%遮荫、60%遮荫和80%遮荫5个处理的多伦芍药幼苗生长和矿质营养积累的变化。结果表明:与CK相比,遮荫处理显著提高了幼苗株高,增幅分别为19.9%、31.1%、52.9%、63.7%;显著降低了根生物量比和根冠比,降幅分别为21.5%、23.6%、29.2%、41.8%和40.6%、44.0%、50.9%、63.2%。40%遮荫、60%遮荫和80%遮荫显著提高了比叶面积,增幅分别为77.0%、84.1%、65.2%,显著增加了叶绿素和类胡萝卜素含量,增幅分别为92.3%、128.7%、98.1%和86.9%、113.1%、90.5%,显著降低了根生物量,降幅分别为61.4%、74.3%、78.6%。与CK、20%遮荫、40%遮荫和80%遮荫处理相比,60%遮荫显著提高了根中磷含量,增幅分别为245.7%、65.9%、40.5%、10.3%;60%遮荫处理的根中钾和镁含量显著高于其他处理,比CK、20%遮荫、40%遮荫和80%遮荫处理分别高102.9%、131.7%、57.0%、63.3%和131.3%、55.1%、40.4%、7.7%。本试验条件下,60%遮荫是多伦芍药幼苗生长适宜的光照条件。     

不同郁闭度对野外回归的梓叶槭幼树形态和生理特征的影响

濒危植物野外回归是扩大极小种群野生植物种群的有效途径。适宜的回归生境是物种生长的必要条件, 研究植物的生理生态特征对不同野外回归生境的适应性, 是科学评价濒危物种种群回归生境适宜性的关键指标。本文以野外回归的极小种群野生植物梓叶槭(Acer catalpifolium)为研究对象, 探讨了无遮荫、林缘、林隙以及林下(郁闭度由小到大) 4种不同光照条件对梓叶槭幼树的形态特征、光合特征、类黄酮指数及叶绿素含量等的影响。结果表明: (1)随着郁闭度的增大, 梓叶槭幼树的基径、冠幅以及新生枝条数量产生差异, 均呈现先增大后减小的趋势; (2)在林缘生境中, 梓叶槭幼树的单叶面积及单叶质量均最大, 比叶面积随着郁闭度的增大而增大; (3)随着郁闭度的增大, 梓叶槭叶片胞间CO₂浓度、蒸腾速率及气孔导度均呈现先减小后增大的趋势, 叶绿素含量呈现上升趋势, 类黄酮指数则呈现先增大后减小的趋势。综上可知, 林缘适宜的光照条件更适合梓叶槭野外回归。这一结果可为梓叶槭以及其他极小种群野生植物的回归生境适宜性的探索研究提供借鉴。     

Spine and dine: A key defensive trait promotes ecological success in spiny ants

A key focus of ecologists is explaining the origin and maintenance of morphological diversity and its association with ecological success. We investigate potential benefits and costs of a common and varied morphological trait, cuticular spines, for foraging behavior, interspecific competition, and predator–prey interactions in naturally co‐occurring spiny ants (Hymenoptera: Formicidae: Polyrhachis) in an experimental setting. We expect that a defensive trait like spines might be associated with more conspicuous foraging, a greater number of workers sent out to forage, and potentially increased competitive ability. Alternatively, consistent with the ecological trade‐off hypothesis, we expect that investment in spines for antipredator defense might be negatively correlated with these other ecological traits. We find little evidence for any costs to ecological traits, instead finding that species with longer spines either outperform or do not differ from species with shorter spines for all tested metrics, including resource discovery rate and foraging effort as well as competitive ability and antipredator defense. Spines appear to confer broad antipredator benefits and serve as a form of defense with undetectable costs to key ecological abilities like resource foraging and competitive ability, providing an explanation for both the ecological success of the study genus and the large number of evolutionary origins of this trait across all ants. This study also provides a rare quantitative empirical test of ecological effects related to a morphological trait in ants.     

Studies on reproductive strategies of Vitex negundo L. var. heterophylla (Franch.) Rehder (Lamiaceae) based on morphological characteristics and SSR markers

Vitex negundo L. var. heterophylla (Franch.) Rehder (Lamiaceae) is an important tree species for soil and water conservation, yet the reproductive ecology of this species remains to be elucidated. To investigate the reproductive traits of V. negundo var. heterophylla, the phenology, morphological characteristics (a suite of characters was assessed: floral morphology, nectar production, pollen viability, and stigma receptivity) and mating system of this species were systematically revealed for the first time in this study. Phenological observations, morphological measurements, and nectar production analysis were conducted during anthesis. Pollen viability and stigma receptivity at different flowering stages were measured by biochemical methods. Finally, genetic analysis based on SSR markers was used to reveal the mating system; outcrossing index and pollen‐ovule ratio were also calculated to help analysis. V. negundo var. heterophylla showed several obvious characteristics of outcrossing, such as abundant and attractive flowers, secreting nectar, and emitting scent. In addition, mechanisms such as homogamy and a short anther‐stigma distance that can promote self‐fertilization were also identified in this species. The coexistence of selfing and outcrossing characteristics demonstrates a predominantly outcrossed mixed mating system (outcrossing rate, t = 95%). The scientific information provided by this study may contribute to conservation of V. negundo var. heterophylla from a reproductive perspective.     

Ecological and morphological determinants of evolutionary diversification in Darwin's finches and their relatives

Darwin''s finches are a classic example of adaptive radiation, a process by which multiple ecologically distinct species rapidly evolve from a single ancestor. Such evolutionary diversification is typically explained by adaptation to new ecological opportunities. However, the ecological diversification of Darwin''s finches following their dispersal to Galápagos was not matched on the same archipelago by other lineages of colonizing land birds, which diversified very little in terms of both species number and morphology. To better understand the causes underlying the extraordinary variation in Darwin''s finches, we analyze the evolutionary dynamics of speciation and trait diversification in Thraupidae, including Coerebinae (Darwin''s finches and relatives) and, their closely related clade, Sporophilinae. For all traits, we observe an early pulse of speciation and morphological diversification followed by prolonged periods of slower steady‐state rates of change. The primary exception is the apparent recent increase in diversification rate in Darwin''s finches coupled with highly variable beak morphology, a potential key factor explaining this adaptive radiation. Our observations illustrate how the exploitation of ecological opportunity by contrasting means can produce clades with similarly high diversification rate yet strikingly different degrees of ecological and morphological differentiation.