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1.
Four Paleozoic bivalved genera are assigned to the new molluscan class Rostroconchia: Eopteria, Euchasma, Conocardium, and Pseudoconocardium. These mollusks have ani uncoiled univalved larval shell; an untorted bivalved adult shell; no hinge teeth, ligament, or adductor muscles; and a fused, almost inflexible. hinge. Rostroconchianis developed separately from the pelecypods through the ribeirioids, but are regarded as more closely related to the Pelecypoda and Scaphopoda than to other known classes of mollusks. 相似文献
2.
在2012～2014年期间,对海南分界洲岛潮间带至潮下带的贝类资源进行了调查,分析了该海域贝类种类与数量、生态分布、区系性质。结果表明,在分界洲岛共采集到贝类137种,隶属于4纲13目44科,其中多板纲1种,腹足纲94种,双壳纲40种,头足纲2种。各科的组成中,宝贝科11种,骨螺科9种,帘蛤科9种,芋螺科8种,凤螺科6种,嵌线螺科6种,其他各科的种类均小于5种。按种的性质而论,分界洲岛贝类大多数属于和珊瑚礁有密切关系的热带种或亚热带种,其区系性质属于印度-西太平洋的印尼-马来亚区。 相似文献
3.
The oldest known "carpoids" of the echinoderm subphylum Homalozoa have been discovered in lower Middle Cambrian rocks of northern Utah. They were free-living benthonic animals characterized by a unique ctenoid feeding apparatus and flattened flexible theca with near bilateral symmetry. A new class, Ctenocystoidea, is proposed to include the new genus and new species, Ctenocystis utahensis. 相似文献
4.
Dinoflagellates are single-celled organisms that reflect the ecological conditions in modern oceans and lakes. Ultrastructural data and molecular phylogeny suggest that they originated in the Neoproterozoic, yet dinoflagellate ancestors are classified only to the Middle Triassic ( approximately 240 million years ago). Examination of dinoflagellate-specific biological markers (dinosteranes and 4alpha-methyl-24-ethylcholestane) in concentrated microfossils with known morphology identified ancient dinoflagellate ancestors from the Early Cambrian ( approximately 520 million years ago). 相似文献
5.
彭水县野生食用菌资源调查 总被引：1，自引：1，他引：0
采用系统抽样调查法及样带调查法,对彭水县野生食用菌资源进行了初步调查。结果表明：彭水县现有野生食用菌2亚门3纲4目19科34属48种,为进一步合理开发利用和保护彭水县真菌资源提供参考。 相似文献
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7.
Johnson WE Eizirik E Pecon-Slattery J Murphy WJ Antunes A Teeling E O'Brien SJ 《Science (New York, N.Y.)》2006,311(5757):73-77
Modern felid species descend from relatively recent (<11 million years ago) divergence and speciation events that produced successful predatory carnivores worldwide but that have confounded taxonomic classifications. A highly resolved molecular phylogeny with divergence dates for all living cat species, derived from autosomal, X-linked, Y-linked, and mitochondrial gene segments (22,789 base pairs) and 16 fossil calibrations define eight principal lineages produced through at least 10 intercontinental migrations facilitated by sea-level fluctuations. A ghost lineage analysis indicates that available felid fossils underestimate (i.e., unrepresented basal branch length) first occurrence by an average of 76%, revealing a low representation of felid lineages in paleontological remains. The phylogenetic performance of distinct gene classes showed that Y-chromosome segments are appreciably more informative than mitochondrial DNA, X-linked, or autosomal genes in resolving the rapid Felidae species radiation. 相似文献
8.
Rosling A Cox F Cruz-Martinez K Ihrmark K Grelet GA Lindahl BD Menkis A James TY 《Science (New York, N.Y.)》2011,333(6044):876-879
Estimates suggest that only one-tenth of the true fungal diversity has been described. Among numerous fungal lineages known only from environmental DNA sequences, Soil Clone Group 1 is the most ubiquitous. These globally distributed fungi may dominate below-ground fungal communities, but their placement in the fungal tree of life has been uncertain. Here, we report cultures of this group and describe the class, Archaeorhizomycetes, phylogenetically placed within subphylum Taphrinomycotina in the Ascomycota. Archaeorhizomycetes comprises hundreds of cryptically reproducing filamentous species that do not form recognizable mycorrhizal structures and have saprotrophic potential, yet are omnipresent in roots and rhizosphere soil and show ecosystem and host root habitat specificity. 相似文献
9.
Ruiz-Pesini E Mishmar D Brandon M Procaccio V Wallace DC 《Science (New York, N.Y.)》2004,303(5655):223-226
A phylogenetic analysis of 1125 global human mitochondrial DNA (mtDNA) sequences permitted positioning of all nucleotide substitutions according to their order of occurrence. The relative frequency and amino acid conservation of internal branch replacement mutations was found to increase from tropical Africa to temperate Europe and arctic northeastern Siberia. Particularly highly conserved amino acid substitutions were found at the roots of multiple mtDNA lineages from higher latitudes. These same lineages correlate with increased propensity for energy deficiency diseases as well as longevity. Thus, specific mtDNA replacement mutations permitted our ancestors to adapt to more northern climates, and these same variants are influencing our health today. 相似文献
10.
Transformation of amorphous calcium phosphate to crystalline dahillite in the radular teeth of chitons 总被引：1，自引：0，他引：1
A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The c axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface. 相似文献
11.
丽江市大型真菌资源及评价 总被引：3，自引：0，他引：3
丽江市是中国大型真菌资源最丰富、产菌时间最长的地区之一,通过实地调查、收集、整理,鉴定出2亚门、4纲、44科、178属大型真菌,其中以冬虫夏草Cordyceps sinensis(Berk.)Sacc.、羊肚菌M orchellaspp.、松口蘑Tricholomaspp.、北风菌Lyophyllumspp.、猴头菌Hericium erinaceus(Bu ll.:Fr.)Pers、鸡油菌Cantharellus cibariusFr.、变绿红菇Russula virescens(Schaeff.)Fr.、鸡土从Ter-m itomycesspp.、金耳Trem ella aurantialbaBandon i et Zang.、松乳菇Lactarius deliciosus(Fr.)S.F.G ray.等珍稀野生菌最为著名,经济价值最大。并对该区大型真菌中重要种类进行了分析和评价,提出了丽江市大型真菌资源的合理开发利用和保护的意见和建议。 相似文献
12.
2009年6、11月和2010年4月共3个水情期（即丰、枯和平水期）对赣江流域一级支流袁河底栖动物群落结构进行了调查。结果表明袁河流域底栖动物17种,隶属于3门5纲12科,其中寡毛类4种,蛭类1种,腹足类5种,瓣鳃类4种,水生昆虫类3种。袁河底栖动物3期总密度和总生物量分别为1 762.29 ind./m2和982.37 g/m2,密度上摇蚊占优势,生物量上铜锈环棱螺占优势。不同水情期现存量也存在差异,平水期的密度和生物量均比丰水期、枯水期的大;丰水期的密度比枯水期的大,而生物量却比枯水期的小。袁河底栖动物优势种为摇蚊、铜锈环棱螺、河蚬和方格短沟蜷。Shannon-Wiener指数、Margalef指数表明袁河底栖动物多样性存在季节性变化,且下游多样性比上中游复杂;Shannon-Wiener指数和FBI指数的结果表明袁河水质已受到不同程度污染。 相似文献
13.
本文报道了黑龙江省果树病害48种,其中包括仁果类(苹果、梨)病害26种;核果类(李、杏、樱桃)病害13种;浆果类(葡萄、草莓)病害9种。上述果树病害病原菌隶属于4个亚门、8个纲、13个目、17个科、30个属,其中鞭毛菌亚门为一个属;子囊菌亚门为13个属;担子菌亚门为2个属;半知菌亚门为14个属。 相似文献
14.
Theory predicts that linkage between genetic loci reduces the efficiency of purifying selection. Because of the permanent linkage of all heritable genetic material, asexual lineages may be exceptionally prone to deleterious-mutation accumulation in both nuclear and organelle genes. Here, we show that the ratio of the rate of amino acid to silent substitution (Ka/Ks) in mitochondrial protein-coding genes is higher in obligately asexual lineages than in sexual lineages of the microcrustacean Daphnia pulex. Using a phylogeny-based approach to quantify the frequency of mutational-effect classes, we estimate that mitochondrial protein-coding genes in asexual lineages accumulate deleterious amino acid substitutions at four times the rate in sexual lineages. These results support the hypothesis that sexual reproduction plays a prominent role in reducing the mutational burden in populations. 相似文献
15.
The Chinese Early Cambrian Chengjiang fauna includes three different anomalocaridids, a globally spread, extinct marine group including the largest known Cambrian animals. Anomalocaridids were active predators, and their presence implies that a complex ecosystem appeared abruptly in the earliest Phanerozoic. Complete specimens display several sets of characters shared only with some other exclusively Cambrian forms. This evidence indicates that anomalocaridids, Opabinia, and Kerygmachela form a monophyletic clade. Certain features indicate arthropod affinities of the lade, and for this group an unnamed (sub)phylum-level taxon within an arthropod (super)phylum is proposed. 相似文献
16.
The finding that microbial communities are active under snow has changed the estimated global rates of biogeochemical processes beneath seasonal snow packs. We used microbiological and molecular techniques to elucidate the phylogenetic composition of undersnow microbial communities in Colorado, the United States. Here, we show that tundra soil microbial biomass reaches its annual peak under snow, and that fungi account for most of the biomass. Phylogenetic analysis of tundra soil fungi revealed a high diversity of fungi and three novel clades that constitute major new groups of fungi (divergent at the subphylum or class level). An abundance of previously unknown fungi that are active beneath the snow substantially broadens our understanding of both the diversity and biogeochemical functioning of fungi in cold environments. 相似文献
17.
箬竹的竹秆和竹叶均可发生各种病虫害，从而降低箬竹的产量和叶片的质量，病虫害问题正严重制约着锦屏县箬竹产业的可持续发展。通过对锦屏县箬竹主要病虫害种类及发生危害情况进行调查，结果表明：锦屏县箬竹的主要虫害涉及5目19科29种昆虫，危害程度达到轻度危害的有15种、中度危害的有5种、重度危害的有9种；主要病害有4种，隶属于2亚门2纲4目，均为重度危害。初步明确了主要病虫害种类，并介绍了主要病虫害的危害特点。 相似文献
18.
[目的]对西藏冬虫夏草寄生镰孢属真菌进行生物学特性分析。[方法]以从新鲜冬虫夏草体上分离得到了镰刀菌菌株为材料,对其进行菌株和孢子形态观察。[结果]此种菌株在大米培养基上生长茂盛,菌丝呈白色绒毛状,基质呈米黄色到粉红色;菌株在(18±4)℃条件下培养2周后,产生乳白色突起,里面有淡黄色的厚垣孢子,分大小2种孢子;通过安斯沃斯分类系统查阅分离到的菌株属于丝孢纲瘤座孢目镰孢属的一种;对菌株的大孢子观察发现有3种类型大孢子,而其中2种的形态比较特别,在安斯沃斯分类系统中未有描述。[结论]此次从西藏冬虫夏草上分离到的菌株,与查阅相关资料记载的镰孢属真菌结构有很大区别,有待于做进一步研究。 相似文献
19.
稻瘟病菌群体的分子遗传学研究——广东省与云南省稻瘟病菌群体遗传及致病型结构的比较分析 总被引：18，自引：1，他引：18
通过基于SRAP标记的分子指纹分析法对由广东省和云南省各40个菌株构成的试验群体进行了遗传结构分析。在相似性系数取0.83时,80个供试菌株被分为25个宗谱;其中广东群体9个宗谱,宗谱频率为22.5%;云南群体16个宗谱,宗谱频率为40.0%,由此说明,后者比前者的遗传多样性高。有趣的是,在25个宗谱中并不存在两个群体共有的宗谱,由此推测它们之间存在明显的遗传特异性或异质性。另一方面,利用中国、日本和IRRI的3套鉴别品种分别对80个供试菌株进行了致病型结构分析。结果表明,在上述3套鉴别品种中,广东群体分别 相似文献
20.
本文报道了黑龙江省蔬菜病害150种,其中十字花科蔬菜(白菜、萝卜、甘兰、芥菜、苤兰、水萝卜、花椰菜、雪里蕻)病害27种;茄科蔬菜(茄子、辣椒、番茄、马铃薯)病害2种;葫芦科蔬菜(黄瓜、西葫芦、南瓜)病害25种;豆科蔬菜(菜豆、豌豆、豇豆、扁豆、蚕豆)病害30种:其他蔬菜(葱、蒜、韭菜、胡萝卜、香菜、菠菜、芹菜、莴苣、茴香)病害39种。上述150种病害病原真菌隶属于真菌5个亚门、9个纲、13个目、16个科、33个属,其中半知菌亚门有19个属,占33个属的57.6%。 相似文献