中国沿海洛氏角毛藻复合群的多样性组成及地理分布

洛氏角毛藻复合群(Chaetoceros lorenzianus complex)指具有与洛氏角毛藻相似形态学特征的物种集合, 它们广泛分布于全球近岸水域。近年国际上关于该复合群的分类学研究取得新进展, 而我国相关研究仍较为滞后。为了弄清我国沿海洛氏角毛藻复合群的物种多样性, 明确物种信息, 厘清种间界限, 为相关研究提供准确的物种鉴定依据, 本研究陆续在中国沿海建立了该复合群的332个单克隆培养株系, 利用光学显微镜、扫描电镜和透射电镜进行了较为详尽的形态学研究, 基于核糖体大亚基编码基因D1-D3区序列, 构建了分子系统学关系。结果表明其形态聚类与分子系统学结论相一致, 显示我国洛氏角毛藻复合群具有较高的物种多样性, 共鉴定到5个物种, 分别是并基角毛藻(C. decipiens)、优美角毛藻(C. elegans)、平孢角毛藻(C. laevisporus)、曼纳角毛藻(C. mannaii)和稀树角毛藻(C. pauciramosus)。研究表明传统认知的光镜下特征, 如群体特征、角毛走势等易变化, 其分类学价值需谨慎应用。角毛的超微结构, 如角毛孔纹的形状、大小、密度等是有效的种间区别特征, 休眠孢子亦是重要的物种识别依据。并基角毛藻和平孢角毛藻在我国沿岸的分布范围最为广泛, 而稀树角毛藻的分布较为有限。     

The role of Callionymus lyra and C. reticulates in the life cycle of Lernaeocera lusci in Belgian coastal waters (Southern Bight of the North Sea)

A survey of the dragonet Callionymus lyra and the reticulated dragonet C. reticulatus from Belgian coastal waters (Southern Bight of the North Sea) in June 1991 revealed 34% of dragonets infected with 1–7 Lernaeocera lusci. This same parasite infected 9% of the reticulated dragonets (mean intensity =1). Parasite size is host-size-dependent. Of the parasites collected from C, lyra 64% were gravid adults (substage X), and a significant positive relationship between the number of eggs and axial length of the parasite was found. The parasites were overdispersed within the dragonet population ( s ²/ m =1.67)     

Dendrochronological dating and provenance determination of a 19th century whaler in Patagonia (Puerto Madryn,Argentina)

Dendrochronological methods have been widely used to determine the date of construction and provenance of shipwrecks. Despite a large number of shipwrecks, the application of dendroarchaeological techniques is relatively incipient in the coasts of South America. This paper presents the results of a dendroarchaeological study conducted at the shipwreck site "Bahía Galenses" (BG), located in the western sector of Golfo Nuevo, on the Patagonian coast of the South Atlantic Ocean. Based on previous archaeological research, two hypotheses were tested in this study. First, the wreck described in the BG 2 sub-site corresponds to a mid-19th-century whaler built in the northeastern US. Second, these remains correspond to the Dolphin, a northeastern American whaler built in Warren (Rhode Island) in 1850 and shipwrecked in the Atlantic coast of Patagonia in 1859. Using dendroarchaeological provenance methods and a novel approach based on the gridded North American Drought Atlas, we found highly significant correlations between the wreck's tree-ring width series and white oak and yellow pine tree-ring reference chronologies from the eastern US. The latest non-cutting dates obtained in this analysis correspond to the year 1849. To our knowledge, our study pioneered the use of dendrochronological methods for dating and establishing the provenance of a whaler's remains on the Atlantic coast of South America and encourages the feasibility for future dendroarchaeological research based on the large number of wooden shipwrecks that occurred in the region.     

Use of a multivariate model using allele frequency distributions to analyse patterns of genetic differentiation among populations

Very few studies have attempted to relate the properties of some ordination techniques to classical tools of population genetics as F -statistics. A multivariate model to analyse population genetics data based on the properties of 'joint scaling' of populations and loci is developed. The design of population genetics data means that this model deals with a modified version of the classical Multiple Correspondence Analysis which is called Constant Row Total-Multiple Correspondence Analysis (CRT-MCA) and is an original tool in population genetics. Such a model allows estimates of the degree of population differentiation by studying the variability of the distribution of allele frequencies in different samples. Some clear relationships exist between some model parameters and the classical F_st statistics. The CRT-MCA also allows all the studied loci to be considered simultaneously and the role of each locus in patterns of population differentiation to be expressed. Such a multivariate approach prevents the use of any pooling strategy as is classically used in studies of hierarchical F -statistics. The relevance of the CRT-MCA model is illustrated by the analysis of population structure of 15 dogwhelk ( Nucella lapillus ) populations in south-west England. The advantages and limitations of CRT-MCA are presented.     

The distribution of brackish water Calanoida (Copepoda) along the coasts of Brazil

The distribution of 18 species of Calanoida Copepoda found in the estuaries of the Brazilian coast is analyzed. A slight tendency of a latitudinal decrease in diversity, from North to South is found. Salinity ranges from the different species are discussed and in some cases interspecific vicariance patterns are found. Two basic types of estuaries of the Brazilian coast are characterized on the basis of environmental parameters and population dynamics.     

Respiration rates predict differences in growth of coast redwood

The relation between growth rate traits (height, basal diameter, stem volume and branch diameter) and two measures of respiration rate [metabolic heat rate (q) and CO₂ production rate (Rco₂)] and their ratio (q/R_co2) was examined on a collection of 192 different genotypes of coast redwoods [Sequoia sempervirens (D.Don) Endl.]. Branch diameter was not correlated with any of the respiratory measures, but the other three growth traits gave highly significant (P < 0.001) correlations with positive slopes. Combining the four growth traits and the three respiratory variables (q, R_Co₂ and q/R_co2) to give two canonical variates, one representing growth and one representing respiration, gives an even stronger linear correlation (r= 0–85). These data suggest that simultaneous assay of multiple respiratory measures on juvenile trees can be used to predict their longer-term growth rates.     

Two different patterns of shell-shape variation in the dog-whelk Nucella lapillus (L.)

Populations of the common dog-whelk, Nucella lapillus (L.), usually show a gradation in mean shell shape related to the exposure of the shore on which they live. Enclaves from exposed headlands have shorter, squatter shells than do their compatriots in shelter. This paper describes the pattern of shell-shape variation shown by populations in the Isles of Scilly and on the north coast of Wales. In both places a gradation is present, but it is not numerically similar, the Welsh population being more elongated. It is concluded that the selective agents are the same in both places. Wave action always eliminates the most elongate-shelled whelks first, and crabs always find it easier to take the animals with the widest apertures to their shells. The reason for the observed differences between the patterns described here lies in the genetic differences between the populations: Scillonian whelks do not have the option of being as elongated as the Welsh ones, which, in turn, cannot show very short squat shells in exposure.     

Microsatellite markers in coast redwood (Sequoia sempervirens)

Five polymorphic microsatellite markers are described for coast redwood, a hexaploid conifer. Dinucleotide (three), trinucleotide (one) and tetranucleotide (one) repeat loci were isolated from a genomic plasmid library and amplified in a test population of 25 second‐growth redwoods. There were three to 11 alleles per locus and observed heterozygosities ranged from 0.00 to 0.80. The nonheterozygous locus (a CTTA repeat) is probably of chloroplast origin and may have potential as a marker for paternal inheritance.     

Invertebrate and protozoan epibionts on the velvet swimming crab Liocarcinus puber (Linnaeus, 1767) from Scotland

Invertebrate and ciliate protozoan epibionts of velvet swimming crabs collected near Millport (Scotland) were analysed. The ecdysis peak for male crabs was at the time of collection while that for female crabs was 2 months later. The epibionts were: the polychaetes Pomatoceros triqueter and Hydroides norvegica, the cirriped Balanus crenatus, the entoproct Barentsia matsushimana, the hydroids Leuckartiara sp. and Clytia sp., and the ciliate protozoans Ephelota plana, Ephelota gemmipara, Chilodochona quennerstedti and Cothurnia longipes. The polychaetes, cirripeds, entoprocts and hydroids, all of them with comparatively larger size, were distributed on the carapace, ventral surface of the cephalothorax and the pereiopods; meanwhile the protozoans, with smaller size, were attached also on pleopods, antennae, eyes and buccal appendages. Chilodochona quennerstedti was the epibiont most abundant on the crab, followed by Ephelota plana. Cothurnia longipes was, in contrast, the least abundant epibiont, followed by Barentsia matsushimana. The anatomical unit most colonized was the left third maxilliped, followed by the left first maxilliped and the ventral surface. The less colonized anatomical units were the left antenna and the ocular orbits. Epibionts on this crab have not been described before. Statistical analyses of the epibiont distribution on the crab were carried out. There were significant correlations between right and left appendages in 66.67% of the cases. Males and females differed significantly with respect to the distribution of epibionts on their anatomical units. The comparison analysis indicated a significant differential distribution of each epibiont species on the anatomical units of the crab. Principal component analysis grouped the epibiont species according to their colonization pattern in three clusters: (1) Ephelota plana, Ephelota gemmipara and Chilodochona quennerstedti; (2) Leuckartiara sp., Clytia sp., Barentsia matsushimana and Cothurnia longipes; and (3) Pomatoceros triqueter, Balanus crenatus and Hydroides norvegica. The hierarchical cluster analysis grouped the anatomical units of the crab in relation to their colonization in five clusters.