Manipulation of host density affects infestation of a peritrich ciliate (Epistylis lacustris) on a calanoid copepod (Leptodiaptomus minutus) in Crystal Lake, Wisconsin, USA

Specimens of the calanoid copepod, Leptodiaptomus minutus, collected in June 1994 in oligotrophic: north temperate Crystal Lake, were infested with the stalked ciliate Epistylis lacustris. E. lacustris was highly specific to L. minutus and no other coexisting zooplankters were infested. Excluding nauplii, nearly 70% of copepods carried 1-20 ciliates, although the maximum load was as high as 250 ciliates. A lower percentage of nauplii were infested by the ciliate; those that were infested had a lower ciliate load than other copepod stages. Infestation by ciliates had no significant influence on the average egg number of female copepods. In a field experiment, higher copepod densities in enclosures resulted in a significantly higher infestation rate, but the ciliate load per individual copepod did not differ significantly among treatments.

南盘江水系三种高原鳅的分化(鲤形目:鳅科)

南盘江是高原鳅属鱼分布的南缘地带,目前发现有3种,其中有2个是新种:抚 仙高原鳅T. fuxianensis sp. nov.和湖高原鳅T. lacustris sp. nov.。它们分 别生活于河道或湖泊中。生活环境的差异导致了它们的分化。形态的分化主要 表现在臀鳍和尾鳍分枝鳍条的数目以及体高、头长、尾柄等 与有关部分的比值, 须的发达程度,骨质鳔囊的形态构造,肛 门的位置和身体斑级纹方面。对2新种 与各自的近似种作了比较。附种的检索表。图4表1参7

三峡库区藻类水华调查及其毒理学研究

三峡水库一期工程蓄水近两年(2003年7月—2005年4月)期间,库区发生过多次藻类“水华”,尤其在阳光充足、气温回升的春季。经鉴定形成水华的藻类主要有拟多甲藻(Peridiniopsissp1,sp2),新星形冠盘藻(Stephanodiscusneoastraea),里海小环藻(Cyclotella caspia),湖沼红胞藻(Rhodomonas lacustris),实球藻(Pandorina morum)和空球藻(Eudorina elegans);其中以拟多甲藻水华涉及面积最大,持续时间最久,

Phylogeny and speciation of the eastern Asian cyprinid genus Sarcocheilichthys

The genus Sarcocheilichthys is a group of small cyprinid fishes comprising 10 species/sub-species widely distributed in East Asia, which represents a valuable model for understanding the speciation of freshwater fishes in East Asia. In the present study, the molecular phylogenetic relationship of the genus Sarcocheilichthys was investigated using a 1140 bp section of the mitochondrial cytochrome b gene. Two different tree-building methods, maximum parsimony (MP) and Bayesian methods, yielded trees with almost the same topology, yielding high bootstrap values or posterior probabilities. The results showed that the genus Sarcocheilichthys consists of two large clades, clades I and II. Clade I contains Sarcocheilichthys lacustris, Sarcocheilichthys sinensis and Sarcocheilichthys parvus, with S. parvus at a basal position. In clade II, Sarcocheilichthys variegatus microoculus is at a basal position; samples of the widespread species, Sarcocheilichthys nigripinnis, form a large subclade containing another valid species Sarcocheilichthys czerskii. Sarcocheilichthys kiangsiensis is retained at an intermediate position. Since S. czerskii is a valid species in the S. nigripinnis clade, remaining samples of S. nigripinnis form a paraphyly. This speciation process is attributed to geographical isolation and special environmental conditions experienced by S. czerskii and stable environments experienced by the other S. nigripinnis populations. This type of speciation process was suggested to be very common. Samples of Sarcocheilichthys sinensis sinensis and Sarcocheilichthys sinensis fukiensis that did not form their own monophyletic groups suggest an early stage of speciation and support their sub-species status. Molecular clock analysis indicates that the two major lineages of the genus Sarcocheilichthys, clades I and II diverged c. 8.89 million years ago (mya). Sarcocheilichthys v. microoculus from Japan probably diverged 4.78 mya from the Chinese group. The northern-southern clades of S. nigripinnis began to diverge c. 2.12 mya, while one lineage of S. nigripinnis evolved into a new species, S. czerski, c. 0.34 mya. (C) 2008 The Authors Journal compilation (C) 2008 The Fisheries Society of the British Isles.

中国急流牙甲族的系统学研究

急流牙甲族Sperchopsini属于鞘翅目Coleoptera牙甲科Hydrophilidae的水牙甲亚科Hydrophilinae，共包括五属，即水龟虫属 Hydrocassis、革牙甲属 Ametor、Sperchopsis、Anticura、Cylomissus，世界共计有25种，我国分布有2属18个种。 本文回顾了水甲虫、牙甲科以及急流牙甲族的研究简史；综述了水甲虫在分类学、保护生物学、形态学、遗传学、分子生物学等方面研究进展，总结了水甲虫与生态因子的关系以及水甲虫作为生态系统健康指示物的可行性。还简要介绍了昆虫分子系统学，以及细胞色素氧化酶亚基I（COI）和rDNA内部转录间隔区（ITS）在昆虫学研究中的应用。 通过对收集到的700余号急流牙甲族的标本观察和分类研究，发现了一新种（内蒙水龟甲Hydrocassis mongolica sp.nov.）。并且对已知全部种类重新作了描述，特别是长茎革牙甲 Ametor elongatus雄性外生殖器部分，首次对7个种类（长茎革牙甲 Ametor elongatus、粗革牙甲 Ametor scabrosus、帝水龟甲 Hydrocassis imperialis、伪舟水龟甲Hydrocassis pesudoscapha、条纹水龟甲Hydrocassis scapulata、舟水龟甲 Hydrocassi scapha、四川水龟甲Hydrocassis sichuana）的雌性个体进行了描述。编制了急流牙甲族的分属、分种检索表。 采用支序分类学的方法对中国急流牙甲族种类的系统发育关系进行探讨。结果显示革牙甲属内的A. latus、A. rudesculptus、A. rugosus 及A. scabrosus 构成单系（不包括A. elongates），支持皱革牙甲A. rugosus和A. latus属于革牙甲属。水龟虫属内H. anhuiensis、H. baoshanensis、H. lacustris、H. pseudoscapha、H. scaphoides、H. scapulata、H. sichuana、H. taiwana、H. uncinata、H. schillhammeri构成一个单系。水龟虫属包括两大类群，一类群包括H. anhuiensis、H. lacustris、H. scapulata、H. sichuana 、H. taiwana，另一类群包括H. baoshanensis、H. scaphoides、 H. schillhammeri 、H. uncinata。两类群的不同之处在于后一类群的阳基侧突上有一齿状凸起。 测序了H. scapulata、H. sichuana和H. mongolica雌雄各一个个体的COI和ITS2序列。全部的COI基因序列为828bp，编码275个氨基酸。H. scapulata的ITS2序列有446bp，H. sichuana的有456bp，H. mongolica的有455bp。用MEGA 3.1计算比对距离（pairwise distances）和构建邻近系统树。结果显示对于COI，种内的比对距离分别是0(H. scapulata)、0.008(H. mongolica)、0.004(H. sichuana)，种间的比对距离在0.024-0.045之间。对于ITS2，种内的比对距离分别为0.005(H. scapulata)、0(H. mongolica)、0.007(H. sichuana)，种间的比对距离在0.028-0.047之间。H. sichuana和新种间的比对距离在0.024-0.037(COI)和0.044(ITS2)。比对距离揭示出种内低于0.008，种间在0.024-1.078之间。因而，它们之间应该是种间关系而不是种内的关系。COI数据集和ITS2数据集所构建的系统树存在一定的差异，前者显示四川水龟甲和条纹水龟甲是姐妹种，后者显示新种和条纹水龟甲是姐妹种。总之，在内蒙古自治区发现的为一新的物种。

Decomposition of emergent macrophyte roots and rhizomes in a northern prairie marsh

Dry mass, nitrogen and phosphorus content in belowground litter of four emergent macrophytes (Typha glauca Godr., Phragmites australis (Cav.) Trin., Scolochloa festucacea (Willd.) Link and Scirpus lacustris L.) were followed for 1.2 years in a series of experimental marshes, Delta Marsh, Manitoba. Litter bags containing roots and rhizome materials of each species were buried in unflooded soil, or soil flooded at three water depths (1–30, 31–60, > 60 cm). There were few differences in dry mass loss in unflooded or flooded soils, and depth of flooding also had little effect on decomposition rates. In the flooded sites, Scolochloa and Phragmites roots lost more mass (48.9–63.8% and 59.2–85.5%, respectively) after 112 days than Typha and Scirpus (36.3–43.6 and 37.0–47.2%, respectively). These differences continued through to the end of the study, except in the shallow sites where Scirpus roots lost more mass and had comparable mass remaining as Scolochloa and Phragmites. In the unflooded sites, there was little difference between species. All litters lost nitrogen (22.9–90.0%) and phosphorus (46.3–92.7%) during the first 112 days, then levels tended to remain constant. Decay rates for our belowground root and rhizome litters were comparable to published literature values for aboveground shoot litter of the same species, except for Phragmites roots and rhizomes which decomposed at a faster rate (−k = 0.0014−0.0032) than shoots (−k = 0.0003−0.0007, [van der Valk, A.G., Rhymer, J.M., Murkin, H.R., 1991. Flooding and the decomposition of litter of four emergent plant species in a prairie wetland. Wetlands 11, 1–16]).