Population structure of beaked redfish (Sebastes mentella Travin, 1951) in the Irminger Sea and adjacent waters inferred from microsatellite data

Samples of beaked redfish from the Irminger Sea and adjacent waters were examined for polymorphism at ten microsatellite loci. The strategy of the material collection enabled investigation of geographic, bathymetric, and temporal variation of this species. The results did not support the evidence on spatial differentiation and temporal stability of the species distribution, favoring the idea that the water area examined was inhabited by a single pelagic population of beaked redfish.     

竹类植物种群生态学研究进展与展望

综述了竹类种群生理生态学、种群动态、繁殖特性、无性系种群特征等几个方面的研究进展,概括了群落水平上竹类种群对森林更新的影响。并从竹类种群克隆多样性与微进化、生长适应机理、开花机制,以及竹类种群与林窗更新等四个方面展望未来竹类种群生态学研究的重点和主要趋势。     

Discrimination of the redfish (Sebastes mentella) stock components in the Irminger Sea and adjacent waters based on meristics,morphometry and biological characteristics

Redfish Sebastes mentella samples were collected in 2004 and 2005 during commercial cruises to the Irminger Sea on board the Polish vessel M/T ‘Wiesbaden’. Ichthyological studies included length and weight measurements, sex, gonad maturity stages and age determinations. Meristic and morphometric measurements were performed on digital images of the redfish. Comparison of the pelagic redfish from the northeastern (depths deeper than 500 m) and southwestern (depths shallower than 500 m) fishing grounds of the Irminger Sea indicates a number of differences including spatial and vertical distribution, ambient temperature, length and age composition. Moreover, 12 morphometric and 4 meristic characters differed significantly between fish samples from these two areas. Results of Cluster Analysis showed the clear grouping of samples into that of the ‘oceanic’ component (depth 300–450 m) and the ‘deep sea’ component (depth 550–800 m). These results were confirmed by Principal Component Analysis, which revealed the separation of samples into two catch depth groups. The share of fish allocated by Discriminant Analysis into the pelagic ‘deep sea’ component in the northeastern area was nearly 92%, while the ‘oceanic’ component was dominant in the southwestern area and comprised more than 88% of the fish. Cluster and Principal Component analyses suggest that the ‘oceanic’ component is a more homogeneous group than the ‘deep sea’ component. These results support the management units recently established by ICES.     

Genetic diversity and population structure in two species of sea cucumber: differing patterns according to mode of development

The population structure of two species of sea cucumber was examined based on mitochondrial DNA sequence analysis. Cucumaria miniata , a species with pelagic nonfeeding larvae lasting less than 2 weeks, and C. pseudocurata , a brooding species lacking a pelagic phase, both occur over similar wide ranges of the northeastern Pacific between Alaska and California. No significant genetic structuring was observed among C. miniata samples with 95% of the observed nucleotide variance attributable to that within population samples. Conversely, only 3.4% of the observed variance was attributed to that within C. pseudocurata population samples, with sampling sites typically greater than 100 km apart. At a finer scale, two C. pseudocurata population samples taken 5 km apart were not statistically different. A significant genetic disjunction was observed among populations of the brooding species, but not in species with pelagic larvae, north of Vancouver Island, Canada, corresponding to the splitting of the California and Alaska currents. Given the observed high levels of genetic diversity in northern samples, this genetic break indicates survival in northern, as well as southern, Pleistocene refugia. These results clearly demonstrate the effects that changes in life-history patterns can have on dispersal, population structure, and the potential for speciation events.     

3S技术在城市绿地生态研究中的应用

介绍了城市绿地生态研究中的遥感特点 ,并论述了 3S技术在城市绿地覆盖清查、绿地三维量估测、绿地生态质量监测、绿地景观格局及其动态分析、适宜度评价和城市绿地景观生态规划上的应用现状 ,提出了现存的问题 ,并对其未来发展的方向作了展望。     

Comparative ecology of subtidal actiniarians from the coasts of California and the Gulf of Maine,USA

Shallow subtidal populations of sea anemones occupying hard substrates along the California (Pacific) and Gulf of Maine (Atlantic) coasts of the USA are compared. The diversity of anemones in the southern Gulf of Maine to 35 m is low (4 species) in contrast to similar habitats in California (at least 11 species), but parallel patterns of individual size, distribution and predation impacts occur. Water motion influences depth distribution and size, while predation affects size, population structure and habitat selection. The nudibranch Aeolidia papillosa exerts a similar pressure on population structure in some anemone species in both areas as a size selective predator. The seastar Dermasterias imbricata appears to magnify the selective pressure for large size in the eastern Pacific coastal zone. Interspecific aggression of anemones determines some distribution patterns in areas of overlap.     

Cultural ecology and the genetical structure of Nicobar island populations

The population of Nicobar is not a single random mating population but divided into a number of subpopulations within each of which essentially random mating takes place. Heterogeneity tests indicate that there is a significant difference among subpopulations for the ABO blood group system but not for the MN system. The overall gene frequencies of the ABO system were: r = 0·914; p = 0·033; q = 0·053. The gene frequencies of the MN system are much more consistent in the area as a whole than in the ABO system. The gene frequencies of the MN system were: M = 0·92 and N = 0·08. The Wahlund's principle yields the value of Ø = 0·0358 for the MN system and the unweighted mean value of Øs equals 0·0301 for the ABO system. The founder effect may have a far greater effect than the effects of chance in the genetical structure of Nicobar subpopulations.     

鹤山人工林大叶相思种群遗传结构的AFLP分析

AFLP分析种源相同、栽种时间相同的不同群落中的大叶相思种群.结果表明,其杂合度在纯林中最高,豆科混交林次之,非豆科混交林中最低.种群遗传多样性主要分布在种群内,达90.73%,不同种群间仅为9.27%.纯林与豆科混交林的大叶相思两种群间遗传结构关系较远,纯林与非豆科混交林种群间遗传关系较近,豆科混交林与非豆科混交林种群间遗传关系居中.表明人工林大叶相思种群总的遗传变化水平较高,但其遗传分化并非基因流作用所致,而是受人工选育与环境变化的影响.     

Genetic diversity and population structure of the commercially harvested sea urchin Paracentrotus lividus (Echinodermata, Echinoidea)

The population structure of the edible Atlanto-Mediterranean sea urchin Paracentrotus lividus is described by analysing sequence variation in a fragment of the mitochondrial gene cytochrome c oxidase subunit I in 127 individuals from 12 localities across south-west Europe. The study revealed high levels of genetic diversity but low levels of genetic structure, suggesting a large degree of gene flow between populations and panmixis within each, the Mediterranean and Atlantic basins. However, we found significant genetic differentiation between the two basins probably due to restricted gene flow across the geographical boundary imposed by the area of the Strait of Gibraltar. Populations of P. lividus appeared to have experienced a recent demographic expansion in the late Pleistocene. We provide new evidence on the population structure of this commercial species, predicting a healthy stock of this sea urchin on the Mediterranean and Atlantic coasts.     

Variations in the population structure and ecology of Matteuccia struthiopteris

The aim of the study was to investigate variation in the structure of a population of Matteuccia struthiopteris (L.) Tod. in N–E Poland depending on its location in a river valley and light availability under tree canopies. Ordination statistical methods and structural equation modeling were used to identify ecological relationships in the population. The analysis showed that optimum growth conditions of M. struthiopteris depend on the canopy cover. As the shading increased, the size of trophophyllous leaves and the production of sporophylls decreased. The relationship between the canopy cover and the optimum growth conditions was best expressed by rootstock diameter and, to a lesser extent, by the number and height of trophophylls. An indirect relationship between the number and height of sporophylls and the canopy cover, by rootstock size and trophophyll quantity, was also identified. This relationship may be caused by the predominance of vegetative forms of reproduction. Based on the correlations between the landscape position vs. rootstock diameter and trophophyll height, a difference in the habitat colonization potential of M. struthiopteris could be detected. Three spatial clusters of M. struthiopteris in the river valley were identified: river bank, river terrace, river valley slopes. These relationships and the distribution of other herbaceous plant species occurring at the plots indicate that the distribution pattern of M. struthiopteris in the study area is determined by diverse environmental conditions, however mainly by light conditions.     

贵州青岩油杉种群年龄结构和动态的研究

研究了青岩油杉种群年龄结构的类型,动态规律及其与群落演替和环境之间的相互关系。结果表明,青岩油杉种群年龄结构有增长型,稳定型,始衰型和中衰型4类,存活曲线呈现凹型,凸型,间断型和散点型,随着群落的发育和演替,青岩油杉种群年龄结构的变化趋势为增长型→稳定型→衰退型→残留型。青岩油杉本身的生物生态学特性,群落内阔叶树的发展,地理隔离,人为干扰等是影响青岩油杉种群年龄结构及其动态变化的重要因素。     

Local selection and population structure in a deep‐sea fish,the roundnose grenadier (Coryphaenoides rupestris)

Local populations within a species can become isolated by stochastic or adaptive processes, though it is most commonly the former that we quantify. Using presumably neutral markers we can assess the time‐dependent process of genetic drift, and thereby quantify patterns of differentiation in support of the effective management of diversity. However, adaptive differences can be overlooked in these studies, and these are the very characteristics that we hope to conserve by managing neutral diversity. In this study, we used 16 hypothetically neutral microsatellite markers to investigate the genetic structure of the roundnose grenadier in the North Atlantic. We found that one locus was a clear outlier under directional selection, with F_ST values much greater than at the remaining loci. Differentiation between populations at this locus was related to depth, suggesting directional selection, presumably acting on a linked locus. Considering only the loci identified as neutral, there remained significant population structure over the region of the North Atlantic studied. In addition to a weak pattern of isolation by distance, we identified a putative barrier to gene flow between sample sites either side of the Charlie‐Gibbs Fracture Zone, which marks the location where the sub‐polar front crosses the Mid‐Atlantic Ridge. This may reflect a boundary across which larvae are differentially distributed in separate current systems to some extent, promoting differentiation by drift. Structure due to both drift and apparent selection should be considered in management policy.     

The genetic population structure and temporal genetic stability of gilthead sea bream Sparus aurata populations in the Aegean and Ionian Seas,using microsatellite DNA markers

We examined 662 gilthead sea bream Sparus aurata from wild samples of the species in the Aegean and Ionian Seas, using 20 EST-linked microsatellite markers, in three multiplex panels, as well as seven anonymous loci. Most of the markers were revealed to be highly polymorphic. We found low genetic differentiation between the sampling stations/areas with total F_ST 0.002 (P < 0.05). Based on comparison of five temporal samples, our results indicate genetic data consistency over time for all tested samples, pointing to stable populations, despite reported repeated escape events. Our results confirm the genetic population structure previously observed in these specific areas, using by far more markers than in previous studies in both coding and non-coding DNA loci. The limited genetic structure and the temporal genetic stability indicate neither major genetic differentiation of local populations by geographic isolation nor influence from anthropogenic factors. These results provide a baseline for future reference in any management programme of both wild and farmed population of S. aurata as well as of other aquaculture species with a potential introgression among farmed and wild populations.     

青岛近岸海域马粪海胆摄食的实验生态学研究

对采自青岛近岸海域的马粪海胆从其对各种饵料的选择和摄食吸收、温度与自身湿重对其摄食率的影响以及摄食活动特征等方面进行实验生态学研究。结果表明 ,马粪海胆在多种海藻并存的情况下 ,对海带及裙带菜等褐藻具明显的选择性 ,对石花菜及孔石莼等藻类的喜好性较差 ,但在食物匮乏条件下 ,马粪海胆的食谱则变得相当广泛。马粪海胆对裙带菜及海带的摄食率均明显高于孔石莼 ,但其对孔石莼的饵料吸收率则高于海带及裙带菜。马粪海胆的摄食受温度条件及自身湿重的影响 ,温度偏离适宜范围对摄食有抑制作用 ,日摄食率与湿重呈显著的指数下降关系 ,摄食率与湿重、温度因子可建立具较高可靠性的指数回归模型。马粪海胆对食物的口面吸附与对其摄食密切相关 ,其摄食活动与湿重呈显著的指数下降关系 ,而与排便活动呈显著的正相关 ,随湿重增加排便活动虽呈下降趋势 ,但未达显著水平。自然光照条件下马粪海胆的夜间摄食强度通常高于日间 ,但在全遮盖的无光照条件下这种昼夜摄食差异则变得不显著 ;对摄食活动的连续观测表明马粪海胆的摄食活动受光强变化的影响 ,其摄食活动的高峰出现在光强减弱的早间及傍晚 ,而日间的强光照环境会抑制其摄食活动     

Molecular ecology meets remote sensing: environmental drivers to population structure of humpback dolphins in the Western Indian Ocean

Genetic analyses of population structure can be placed in explicit environmental contexts if appropriate environmental data are available. Here, we use high-coverage and high-resolution oceanographic and genetic sequence data to assess population structure patterns and their potential environmental influences for humpback dolphins in the Western Indian Ocean. We analyzed mitochondrial DNA data from 94 dolphins from the coasts of South Africa, Mozambique, Tanzania and Oman, employing frequency-based and maximum-likelihood algorithms to assess population structure and migration patterns. The genetic data were combined with 13 years of remote sensing oceanographic data of variables known to influence cetacean dispersal and population structure. Our analyses show strong and highly significant genetic structure between all putative populations, except for those in South Africa and Mozambique. Interestingly, the oceanographic data display marked environmental heterogeneity between all sampling areas and a degree of overlap between South Africa and Mozambique. Our combined analyses therefore suggest the occurrence of genetically isolated populations of humpback dolphins in areas that are environmentally distinct. This study highlights the utility of molecular tools in combination with high-resolution and high-coverage environmental data to address questions not only pertaining to genetic population structure, but also to relevant ecological processes in marine species.     

Quantitative observations on the population ecology of Branchiura sowerbyi (Oligochaeta,Tubificidae)

Cohorts of Branchiura sowerbyi were reared at different temperatures and initial population densities in order to obtain data suitable for the interpretation of population dynamics in field populations. Percent hatching from cocoons reaches its maximum at 25 °C and decreases towards lower and higher temperatures. Embryonic development time, T_E, was measured and the relative threshold temperature, 10 °C, calculated by extrapolation. The degree day requirement for embryo development is 195 °C d. The time of first cocoon laying (T_gm) was observed and the ratio T_E/T_gm was seen to fit with that of other tubificid species cultured so far. Embryo mortality is rather high, while worm mortality is low or very low. Fecundity increases from 15 to 20 °C but decreases at 25 °C. A mathematical model for the simulation of population densities with four size-stage compartments is suggested. It could be used for the optimization of worm uptake (simulated as stage specific mortality) in mass cultures reared for the production of Branchiura, to be used as food for fish fingerlings.     

古尔班通古特沙漠半固定沙丘植物群落物种组成和种群结构

通过野外调查,研究古尔班通古特沙漠半固定沙丘植物群落的物种组成,采用株高、冠幅、体积大小级代替年龄结构,分析了典型灌木种群的生长状态及发展趋势.结果表明:在古尔班通古特沙漠半固定沙丘共调查到23种植物,出现最多的是藜科,6属8种,其次是菊科,5属6种,该沙漠植被组成数目少,群落结构简单.白梭梭主要分布在丘顶,为稳定增长型种群,而梭梭数量少.油蒿是当地工程建设后进行植被恢复而引入的物种,主要分布在迎风坡和丘顶,为增长型年龄结构,有很大的增长潜力,已经影响到原有的物种组成.白皮沙拐枣和蛇麻黄幼苗缺失,幼龄个体少,形成衰退型年龄结构,且白皮沙拐枣的空间分布区域与油蒿重合,未来可能被油蒿替代.     

A tale of two worlds: molecular ecology and population structure of the threatened Florida scrub-jay

Elsewhere in this issue of Molecular Ecology , Coulon et al . provide a detailed analysis of population structure of the threatened Florida scrub-jay ( Aphelocoma coerulescens ) using genetic markers and compare it to that inferred from previous demographic surveys and observed dispersal behaviour in this species. In contrast to previous attempts at such comparisons, estimates from the two methods are reasonably congruent. Although challenges remain, Coulon et al .'s analyses demonstrate the potential for closing the gap between these alternative methodologies, and ultimately for future genetic surveys to be used confidently in conservation planning.