基于模式产地的分子证据澄清南平鳞毛蕨的分类学地位

地球上有多少物种一直以来都是人们极度关注的问题, 而存疑物种是造成该问题难以解决的重要阻碍之一。目前, 模式标本是存疑物种得以确定的唯一凭证标准, 然而, 因其特殊的分类学地位而难以进行有效的观察和研究。因此, 前往模式产地寻找存疑物种的原始信息成为最有效的替代途径。随着分子生物学, 特别是DNA条形码技术在物种分类与鉴定中的广泛应用, 准确而快速鉴定存疑物种成为可能。以存疑物种——南平鳞毛蕨(Dryopteris yenpingensis)为例, 利用来自模式产地的分子数据进行DNA条形码分析, 并结合形态学特征澄清了南平鳞毛蕨的分类学地位, 确定南平鳞毛蕨与荔波鳞毛蕨(D. liboensis)为同一物种, 同意将荔波鳞毛蕨作为其异名。研究结果和方法可为今后澄清更多存疑物种的分类学地位提供参考。     

The sex-peptide gene (Acp70A) is duplicated in Drosophila subobscura

A 3.1-kb region of Drosophila subobscura homologous to the Acp70A region of D. melanogaster, which contains the sex-peptide gene, was cloned and sequenced. This region contains an approximately 600-bp duplication that includes the sex-peptide and its 5′ and 3′ flanking regions. The preproteins are 54 and 56 amino acids long, respectively (as compared to 55 amino acids in D. melanogaster), and each includes a 19-amino-acid-long signal peptide. The C-terminal part of the mature peptide is highly conserved between D. melanogaster and the two copies of D. subobscura. In this species, both copies of the gene are transcribed and, like in D. melanogaster, only expressed in males. The duplicated region includes 300 bp upstream of the gene that would therefore seem sufficient for their expression in males. This region presents at its 5′ end a stretch 93-bp that has a high similarity with the corresponding region of D. melanogaster and could be part of a still unidentified regulatory element of these genes.     

东太平洋公海茎柔鱼饵料中鱼类和头足类组成初步分析

茎柔鱼(Dosidicus gigas)广泛分布于东太平洋海域,在海洋生态系统中扮演着重要角色。本研究根据2019年6—12月我国鱿钓生产船在东太平洋公海采集的62尾茎柔鱼样本,对其胃含物残留的4131个耳石和75个角质颚样本进行鉴定分析。结果表明: 茎柔鱼主要摄食鱼类10种、头足类4种。从摄食饵料的出现频率和数量百分比来看,主要摄食的鱼类饵料为荧串光鱼、朗明灯鱼和墨西哥尾灯鱼,荧串光鱼在不同胴长组的茎柔鱼胃内均有出现,是茎柔鱼最重要的饵料;摄食的头足类主要有茎柔鱼、鸢乌贼和爪乌贼。随着胴长的增大,茎柔鱼摄食的饵料种类不断增加,头足类和灯笼鱼饵料比例增加,且摄食的饵料尺寸增大,摄食营养结构发生改变,摄食营养水平随之提高。研究结果可为评估不同饵料生物在茎柔鱼食性转变过程中的食物贡献提供基础资料。     

金钟藤入侵群落的种间联结及生态位特征

金钟藤(Decalobanthus boisianus)是林业有害植物, 其暴发生长和扩散对森林生态系统造成了严重破坏。本文以海南岛48个金钟藤典型分布群落为研究对象, 用方差比率法和贡献定律法探究群落的稳定性; 用χ ²统计量、联结系数(AC)、共同出现百分率(PC)、Ochiai指数和Dice指数分析金钟藤与伴生物种的种间联结关系; 用生态位宽度、生态位相似性系数和生态位重叠指数研究群落中各物种的生态位特征, 以期为金钟藤生物防治的植物物种筛选提供借鉴。结果表明: (1)金钟藤所在48个群落共有156种伴生植物, 其中大戟科、茜草科、桑科、无患子科和樟科植物占优势; (2)群落中优势物种呈正联结关系, 植物种类累积倒数百分比与累积相对频度交点坐标为(44.53, 55.47), 远离稳定交点坐标(20, 80), 说明群落处于不稳定状态; (3)金钟藤与芳槁润楠(Machilus suaveolens)、黄椿木姜子(Litsea variabilis)、岭南山竹子(Garcinia oblongifolia)、显脉杜英(Elaeocarpus dubius)、鸭脚木(Schefflera octophylla)和银柴(Aporusa dioica)都紧密关联, 说明金钟藤与这些物种的资源利用方式较相似; (4)金钟藤的生态位宽度最大, 与伴生物种间的生态位重叠度较高, 但伴生物种间的生态位重叠度较低。金钟藤的入侵导致群落处于不稳定状态, 并与伴生物种间存在激烈的竞争关系。因此, 建议在金钟藤已入侵的群落中大量栽种芳槁润楠、黄椿木姜子、显脉杜英、鸭脚木和银柴, 以遏制其蔓延; 大量栽种翻白叶树(Pterospermum heterophyllum)、海南菜豆树(Radermachera hainanensis)、九节(Psychotria rubra)和肉实树(Sarcosperma laurinum)用于金钟藤入侵群落的植被恢复。     

Earthworms (Clitellata, Acanthodrilidae) of the mountains of Eastern Jamaica

Fourteen species new to science are described from material collected at several sites in the Blue Mountains and the John Crow Mountains of eastern Jamaica, doubling the known endemic Jamaican earthworm fauna. New data on Dichogaster montecyanensis (Sims) are provided. All species are placed in the genus Dichogaster Beddard, which is here treated sensu lato, i.e. including Eutrigaster Cognetti. Eight of the new species have lost the posterior pair of prostates and the seminal grooves of the male field. These are D. bromeliocola, D. crossleyi, D. davidi, D. garciai, D. harperi, D. haruvi, D. hendrixi, and D. johnsoni. D. sydneyi n. sp. has independently lost the posterior prostates but not the seminal grooves. The new species D. altissima and D. manleyi have the conventional dichogastrine prostatic battery and male field characteristics. Three species described here, D. farri, D. garrawayi, and D. marleyi, all have a third pair of prostates in the 20th segment, no seminal grooves, dorsal paired intestinal caeca in segment lxv, and lack penial setae.     

Chloroplast DNA and the determination of species status in the Disa tripetaloides complex (Orchidaceae), and its relationships to three species Racemosae, section Disa

Disa cardinalis and three populations within the D. tripetaloides species complex contain variation in their chloroplast DNA (cpDNA) variability. All four taxa possessed unique cpDNAs and sequence divergence values ranged from 0.34 to 1.03%. A phylogeny of these genomes was reconstructed, along with the genomes of three other species, D. racemosa, D. uniflora and D. venosa, all of which are also section Disa and series RAcemosae, to determine the relationship of these closely related species to the D. tripetaloides complex. A phylogeny of the taxa using morphological data was also reconstructed. Outgroup comparison was made with D. sagittalis, a member of section Coryphaea. Although the molecular and morphological data were not completely congruent, both data types revealed D. cardinalis, rather than D. tripetaloides ssp. aurata, to be more closely allied with D. tripetaloides ssp. tripetaloides, suggesting that D. tripetaloides ssp. aurata should be elevated to species rank. Additionally, the high sequence divergence observed between the Natal and Cape populations, coupled with their geographical isolation and alternate flowering seasons, suggests that these two D. tripetaloides ssp. tripetaloides populations may, in fact, be more appropriately ranked as subspecies.     

Comparative analysis of complete plastid genome reveals powerful barcode regions for identifying wood of Dalbergia odorifera and D. tonkinensis (Leguminosae)

Dalbergia odorifera T. C. Chen (Leguminosae), a rare and endangered tree species endemic to Hainan Island of China, produces the most expensive and rarest wood in China. The wood characteristics of D. odorifera are remarkably similar to those of D. tonkinensis (a much less sought-after species from Vietnam), and the DNA from wood is often highly degraded, making it very difficult to identify the two species using anatomical features or DNA barcoding based on regular DNA markers. To solve the confusion of identifying wood reliably from the two species, we built and analyzed the plastome library of 26 samples from 18 Dalbergia species, of which 12 samples from eight closely related species of D. odorifera are newly sequenced in this study. Phylogenomic analysis suggested that the relationships among the 26 samples are mostly well resolved, and conspecific individuals from different populations of D. odorifera and D. tonkinensis clustered together. Between the plastid genomes of the two species, we identified 129 indels and 114 single nucleotide polymorphisms. By assessing a subset of 20 nucleotide polymorphisms and 10 indels using 37 population-level samples (20 samples of D. odorifera and 17 samples of D. tonkinensis), we recovered eight species-specific barcode regions that could be suitable for identifying the wood D. odorifera and D. tonkinensis. To examine their utility in wood identification, we amplified the eight DNA barcodes using six wood samples and recovered an amplification success rate of 83.3%, demonstrating a reliable method for precise wood identification of the two species.     

大型枝角类蚤状溞对小型热带湖泊浮游植物群落影响的研究

2006年4月10日至2006年4月22日,采用原位吊瓶实验的方法,在暨南大学校园明湖中进行了大型枝角类蚤状溞(Daphnia pulex)对浮游植物种群变化和群落结构影响的实验。实验初期,明湖浮游植物群落的组成是以飞燕角甲藻(Ceratium hirundinella)和单角盘星藻(Pediastrum simplex)为优势种。在室内将蚤状溞培养至体长2mm以上,将蚤状溞加入到装满湖水的4.5L的透明瓶中,设置4个梯度:0ind(A,对照),10ind.(B),20ind(C)和30ind(D),每个梯度有3个平行,将实验瓶置于水表层50cm处。12d后实验结束,不同处理之间的浮游植物种群数量和组成有了明显的差异。与对照组相比,飞燕角甲藻和颗粒直链藻(Meclosira granulata)密度在实验组B、C和D中下降明显;小环藻(Cyclotella)和栅藻(Scenedesmus)等小型浮游植物在牧食压力比较大的C和D瓶中密度低于对照组,而在牧食压力相对较低的B瓶中,它们的密度高于对照组,这可能是由于蚤状溞加速了水体的营养盐循环反过来促进这些小型浮游植物的生长。处理组中绿藻门的盘星藻数量没有明显的下降,这与盘星藻不能被浮游动物直接滤食有关。实验结果表明蚤状溞对浮游植物的群落数量和组成的影响程度与其自身的种群密度密切相关,也与浮游植物群落结构有关。由于飞燕角甲藻是一种细胞较大的种类,蚤状溞对它的抑制作用主要是通过机械伤害作用实现的。     

三峡库区不同消落带下中华蚊母树群落特征及其与土壤环境因子的关系

中华蚊母树(Distylium chinense)是华中地区特有种, 在三峡库区局部地段占优势形成群落。对三峡库区不同生境下中华蚊母树群落特征及其与土壤环境因子的关系进行研究可为其保护及消落带植被恢复提供科学依据。运用数据分类和排序等方法, 对中华蚊母树群落物种组成、植物区系、物种多样性及其与土壤环境因子的关系进行研究。结果表明, 共发现维管植物56种, 隶属于36科54属, 植物区系以世界分布、泛热带分布和北温带分布为主, 生活型以草本和灌木为主。自然消落带灌木层重要值最大的是中华蚊母树, 草本层重要值最大的是藤本植物地果(Ficus tikoua), 主要伴生种为具有一定水淹耐受性的灌木和多年生草本, 如小梾木(Swida paucinervis)、白茅(Imperata cylindrica)等; 反季节消落带灌木层仅中华蚊母树一种, 草本层重要值最大的物种是狗牙根(Cynodon dactylon), 主要伴生种为苍耳(Xanthium sibiricum)、苘麻(Abutilon theophrastic)等一年生草本。双向聚类分析将调查的6个样地分为四大类群: 中华蚊母树+小梾木群落、中华蚊母树+地果群落、中华蚊母树+细叶水团花(Adina rubella)群落、中华蚊母树+狗牙根群落。典范对应分析表明, 海拔高度和土壤pH是影响中华蚊母树群落物种分布的主要环境因子, 土壤有机质、全氮、全磷和速效钾含量是次要因素, 但它们是影响群落物种多样性指数的主要因子, 其中土壤氮是群落的限制因子。因此, 在反季节消落带植被重建中, 对中华蚊母树群落进行构建时, 除考虑细叶水团花、小梾木等作为高海拔消落带伴生物种外, 还应增加土壤氮和钾的供给, 使中华蚊母树群落保持较高的物种多样性, 维持消落带生态系统稳定。     

Indirect Immunofluorescence and FISH for Enumerating Contaminated Site Sulfate-Reducers

A new species of sulfate-reducer, Desulfosporosinus meridiei, was recently isolated from gasoline-contaminated anaerobic groundwater in which degradation of toluene and other hydrocarbons occurred. Ground-water from inside (three sites) and outside (one site) the contaminant plume was probed with specific polyclonal antibodies raised against two strains of D. meridiei (strains T2 and S6). Molecular 16S rRNA probes designed to hybridize with cells of D. meridiei were also used. Cell counts using antistrain T2 antibodies (specific for all strains of D. meridiei and two strains of D. orientis) were similar (10³ cells/mL) both inside and outside the plume as were total DAPI counts (10⁶ cells/mL). The numbers of cells stained with antibodies specific for Group B strains of D. meridiei varied between locations. The molecular probes DSP477A and DSP477B were designed for, and were effective on, pure cultures of D. meridiei and were able to distinguish this species from Desulfovibrio desulfuricans in hybridization experiments. No cells were seen to hybridize with probe DSP477B in groundwater samples. Cell counts in groundwater using the universal eubacterial probe, EUB338, were only 8% to 29% of DAPI counts. Fluorescence intensity was poor and auto fluorescence of particles made counting difficult. This study showed that molecular probing using techniques commonly employed in many laboratories was of little use for evaluating microbial populations in this groundwater. Polyclonal antibodies were considerably more useful for identifying populations of specific cells. The lack of difference in cell numbers between contaminated and nearby uncontami-nated groundwater suggests that cell counts will not always be useful as indicators of intrinsic remediation.     

Genetic evidence against a morphologically suggestive conspecificity of Dermacentor reticulatus and D. marginatus (Acari: Ixodidae)

Dermacentor reticulatus and D. marginatus exhibit overlapping phenotypes. The possibility of conspecificity was investigated on the nucleotide level by comparing DNA sequences of the second internal transcribed spacer (ITS 2) of the rDNA gene. The inter-specific polymorphism was more than 20-times greater than the intra-specific polymorphism of 3 D. reticulatus strains of different geographic origins. Furthermore, the degree of polymorphisms between D. reticulatus and D. marginatus was found to be of the same order of magnitude as that between D. andersoni and D. variabilis, for which separate species status is accepted. These genomic findings do not support a possible conspecificity of D. reticulatus and D. marginatus.     

The tegument of the monogenean gill parasites Dactylogyrus amphibothrium and D. hemiamphibothrium

The general features of the tegument of Dactylogyrus amphibothrium and D. hemiamphibothrium, gill parasites of the freshwater fish Acerina cernua, resemble those of other monogeneans. However, in D. amphibothrium the tegument bears spike-like structures associated with tegumental sacs and these have not previously been reported in monogeneans. The origin of the sacs and the possible functions of the spikes and sacs are discussed. It has been found that the tegument covering the two pads located on the ventral surface of D. amphibothrium does not differ in structure from the general body tegument; the pad regions are elevated above the general body surface because of the presence of large glandular sub-tegumentary organs which communicate with the receptaculum seminis. This indicates that the pads play a part in the reproductive biology of the parasite. In spite of the fact that the micro-environments of D. amphibothrium and D. hemiamphibothrium are the same or broadly similar, D. hemiamphibothrium has no spikes, tegumentary sacs or glandular pads and has only two kinds of tegumentary secretory inclusion compared with three kinds in D. amphibothrium. One of the three kinds of cyton in D. amphibothrium is restricted to the ventro-lateral regions of the posterior half of the body. The tegument of both D. amphibothrium and D. hemiamphibothrium differs from that of other adult monogeneans so far investigated in the presence of granular endoplasmic reticulum in the outer syncytial layer.     

The chorion genes of the medfly. II. DNA sequence evolution of the autosomal chorion genes s18, s15, s19 and s16 in Diptera

We present a total of approximately 15 kb of DNA sequences, encompassing four chorion genes Ccs18, Ccs15, Ccs19, Cc16 and their flanking DNA in the medfly C. capitata. Comparison of coding regions, introns and intergenic sequences in five Dipteran species, D. melanogaster, D. subobscura, D. virilis, D. grimshawi and C. capitata documented an extensive divergence in introns and coding regions, but few well conserved elements in the proximal 5′ flanking regions in all species. These elements are related to conserved regulatory features of three of the genes, including tissue- and temporal regulation. In the fourth, gene s15, significant alterations in the 5′ flanking region may be responsible for its changed temporal regulation in C. capitata. One long intergenic sequence, located in the distal 5′ flanking region of gene s18, is homologous to ACE3, a major amplification control element and contains an 80-bp A/T-rich sequence, known to stimulate strong binding of the origin recognition complex (ORC) in D. melanogaster. Analysis of the nucleotide composition of all chorion genes in C. capitata and D. melanogaster showed that C. capitata exhibit less biased representation of synonymous codons than does D. melanogaster.     

A Late Permian flora with Dicroidium from the Dead Sea region, Jordan

Three new species of Dicroidium, D. irnensis, D. jordanensis and D. robustum, are described from the Um Irna Formation (Upper Permian) of the Dead Sea region, Jordan. The plant remains are preserved as compressions with excellent cuticles. These are the earliest unequivocal records of Dicroidium, a genus that is typical for the Triassic of Gondwana. It is also the northernmost occurrence of this genus that apparently originated in the Permian in the palaeotropics. Middle and Late Permian floras from the Arabian Peninsula and adjacent regions show a remarkable mixture of elements from different floral provinces, i.e. Euramerica, Cathaysia and Gondwana. The climatic amelioration in the Early Triassic apparently enabled Dicroidium to migrate southward and eventually colonise the entire Gondwana region. Dicroidium is one of the very few megaplant genera not affected by the end-Permian biotic crisis, the largest Phanerozoic extinction event.     

Northern Hemisphere megafossil of Dacrycarpus (Podocarpaceae) from the Miocene of South China and its evolutionary and paleoecological implications

The modern genus Dacrycarpus (Endl.) de Laub. of the family Podocarpaceae, containing nine species, is mainly distributed in tropical mountain rainforests of the southwestern Pacific region, ranging from New Zealand to low‐latitude Asia. This genus has abundant fossil records in both hemispheres, but all the known megafossils were limited to Australasia and South America. Here we report on Dacrycarpus guipingensis sp. nov. from the Miocene Erzitang Formation of Guangxi, South China. This is the first megafossil of Dacrycarpus in the Northern Hemisphere. The new species is represented by mummified dimorphic foliage, ovuliferous shoots, and a male cone with in situ pollen. It resembles the extant Dacrycarpus imbricatus (Blume) de Laub., which is common in rainforests from southern China and northern Myanmar to Fiji. This paper presents the first data on the anatomical structure of seed cone and exine ultrastructure of Dacrycarpus in situ pollen grains from a fossil material by using computed tomography scanning and ultrathin sectioning. For comparative purpose, data on the pollen morphology and ultrastructure were obtained for modern D. imbricatus for the first time. The D. guipingensis fossils strongly suggest the Miocene arrival of Dacrycarpus in Asia from the Southern Hemisphere. Based on the modern ecological niche and related fossil elements, this fossil locality was probably covered by conifer–broad‐leaved mountain rainforests during the Miocene.     

黄土丘陵区两种丛藓科植物展叶时长及关键影响因子

藓类植物是变水植物,展叶时长是影响其生长发育的关键。目前,干旱半干旱区藓类植物野外生长发育动态及其影响因子的研究鲜见报道。本研究以黄土丘陵区常见的土生对齿藓和扭口藓为对象,研究了9月5日—11月25日野外自然条件下两种藓类的展叶情况。结果表明: 9—10月,两种藓类叶片表现出有规律的“展开-闭合-展开”的日动态变化,并且土生对齿藓叶片在上午闭合时间较扭口藓平均提前0.68 h,下午叶片展开时间则推后了1.79 h。两种藓类在雨季时展叶时间较长,土生对齿藓展叶时长为251 min,较扭口藓(361 min)低30.4%。近地表大气相对湿度是影响藓株展叶时长的关键因子,藓种的形态结构也会影响展叶时长;相比于土生对齿藓,扭口藓植株较为低矮,中肋占叶片比例大,茎皮部细胞镶嵌结构更为突出,其展叶时的湿度阈值(54.3%)低于土生对齿藓(60.1%)。展叶时长主要受湿度的影响,扭口藓对环境的适应性更强。     

西藏翠雀花属七新种

描述了自西藏发现的毛茛科翠雀花属七新种,隆子翠雀花,黄花翠雀花,绿房翠雀花,二距翠雀花,扎囊翠雀花,宽片翠雀花和狭裂翠雀花,并给出其等与近缘种的区别特征。     

Competitive Superiority of Early Acting Species: A Case Study of Opiine Fruit Fly Parasitoids

Koinobiont parasitoids that attack an early host stage may have an advantage in suppressing competing parasitoids that attack later stages of the same host. We examined the competitive interaction between the two most important parasitoids of tephritid fruit flies in Hawaii, Fopius arisanus (Sonan), and Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). The former species attacks host eggs while the latter attacks host larvae, and both species emerge as adults from the host puparia. F. arisanus physiologically suppressed egg development of D. longicaudata. Over 90% of D. longicaudata eggs died in the presence of F. arisanus larvae within host larvae of either the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) or the oriental fruit fly, Bactrocera dorsalis (Hendel). D. longicaudata appeared not to discriminate against hosts previously parasitized by F. arisanus. The mechanism that F. arisanus uses to eliminate D. longicaudata is similar to that which it employs to eliminate five other larval fruit fly parasitoids so far reported in Hawaii. This suggests that there is a broad competitive superiority of the early acting species in fruit fly parasitoids. We discuss the implication of this in relation to future biological control introductions against tephritid fruit flies.