渤、黄海蓝点马鲛种群鉴别的研究

本文讨论了渤海和黄海海域蓝点马鲛的种群问题,通过对各项性状特征差异的分析、计算以及生殖、分布回游习性的综合对比判别的结果表明:渤海与黄海诸海域群体均属同一种群。但黄海南部群体可视为同一种群的不同群体。     

中国沿海日本鳗鲡幼苗群体鉴别研究

本文研究了中国沿海日本鳗鲡Anguilla japanica Temminck et Schlegel幼苗的群体问题。通过各项形态性状的观察、计量和差异统计比较,结合有关资料进行了综合分析。所得结果表明:我国沿海主要鳗苗产区的群体,相互间存在着一定的关系,均属同一个种、同一个种群,惟作为今后渔业资源管理的基本单元,其间尚可区分出江苏、长江口、浙江、福建、广东等若干不同的群体。     

Molecular and morphologic approaches to discrimination of variability patterns in chub mackerel, Scomber japonicus

The systematic status and the evolutionary biology of chub mackerel (Scomber japonicus) in the South West Atlantic Ocean is confusing with an unknown degree of genetic differentiation and reproductive isolation between units. Simultaneous genetic and morphologic analyses were made on 227 fish collected from two areas of the South West Atlantic Ocean and one from the Mediterranean Sea. The genetic analysis was based on 36 protein-coding loci, 16 of which were variable. The morphologic analyses include six morphometric length measurements and a meristic character. Correspondence between genetic and morphologic variability patterns indicates isolated Mediterranean and Southwest Atlantic subgroups of S. japonicus and, less clearly, possible additional divergence in two regional stocks within the latter group. The most conservative approach to management is to manage the stocks independently of one another.     

Life-history correlates of maximum population growth rates in marine fishes

Theory predicts that populations of animals with late maturity, low fecundity, large body size and low body growth rates will have low potential rates of population increase at low abundance. If this is true, then these traits may be used to predict the intrinsic rate of increase for species or populations, as well as extinction risks. We used life-history and population data for 63 stocks of commercially exploited fish species from the northeast Atlantic to test relationships between life-history parameters and the rate of population increase at low abundance. We used cross-taxonomic analyses among stocks and among species, and analyses that accounted for phylogenetic relationships. These analyses confirmed that large-bodied, slow-growing stocks and species had significantly lower rates of recruitment and adult production per spawning adult at low abundance. Furthermore, high ages at maturity were significantly correlated with low maximum recruit production. Contrary to expectation, fecundity was significantly negatively related to recruit production, due to its positive relationship with maximum body size. Our results support theoretical predictions, and suggest that a simply measured life-history parameter can provide a useful tool for predicting rates of recovery from low population abundance.     

猕猴桃嫁接试验

本文报道猕猴桃不同嫁接时期、嫁接方法和不同分类群的砧木试验结果,猕猴桃最适宜的嫁接时期是落叶后至翌年萌芽前,嫁接方法以切接为好,嫁接成活率均在90％以上。同种和同一分类群的砧穗间有良好的亲和力,嫁接均有较高的成活率。不同分类群间嫁接效果较差,如中华猕猴桃桂海4号嫁接于中华猕猴桃砧木上的成活率,生长情况均比嫁接其它分类群为砧的有显著差异。     

HERITABLE VARIATION IN RESOURCE UTILIZATION AND RESPONSE IN A WINERY POPULATION OF DROSOPHILA MELANOGASTER

It has been found that Drosophila melanogaster lines from the “Chateau Tahbilk” winery cellar had higher larval ethanol resistance than lines originating from outside the cellar. Because the adaptive significance of this trait is unclear, we have reexamined genetic microdifferentiation at Tahbilk with other resources and different tests for ethanol adaptation. Cellar stocks tended to be more resistant to starvation after exposure to wine seepage than stocks originating from orchard traps outside the cellar. Lines from a grape residue pile were also more resistant to starvation after seepage exposure than orchard stocks even though these collection sites were a few meters apart. Cellar and orchard stocks did not differ in ethanol resistance as measured by larval viability tests on low sucrose medium. However, stocks from the grape residue pile showed an increase in adult longevity over ethanol vapor compared to those from the cellar or orchard stocks. These differences were not due to maternal effects. In laboratory tests of behavioral responses, cellar stocks were relatively more attracted to seepage than orchard stocks in one year but not in the other two years. The findings suggest some adaptive differentiation related to resource heterogeneity at Tahbilk.     

EXPERIMENTS ON TOLERATION OF TEMPERATURE BY DROSOPHILA

1. Most wild stocks of Drosophila melanogaster can be bred indefinitely on banana agar at a temperature of 31°C. There is no relation between the geographical origin of these stocks and their ability to tolerate this temperature. 2. A single wild stock has been found which will breed for only one generation at temperatures above 29°C. The offspring hatched at 31°C. will breed normally at 24°C. This difference from other wild stocks is apparently genetic, but its genetic basis has not yet been worked out. 3. The mutant stocks of D. melanogaster tested by us will breed for only one generation at 31°C. and their offspring at this temperature are also fertile at 24°C. This condition is apparently a physiological effect of the presence of any of the mutant genes in a homozygous condition. 4. Similar tests indicate that wild stocks of D. virilis and Chymomyza procnemis will breed at 31°C., while D. simulans, D. immigrans, and D. funebris will not. The last two species are northern forms not commonly found in the tropics. 5. Both male and female flies from mutant stocks hatched at 31°C. produce offspring at this temperature if mated to flies hatched at 24°C. Their germ cells are therefore capable of development, and the cause of their failure to develop at 31°C. when inbred must lie either in the failure of the germ cells to reach each other or in the fertilization process itself.     

Seasonal stability and spatial variability of parasites in Brazilian sandperch Pinguipes brasilianus from the Northern Argentine Sea: evidence for stock discrimination

The use of parasites as biological tags allowed the identification of two stocks of Brazilian sandperch Pinguipes brasilianus , in the Bonaerense region of the Argentine Sea. A total of 156 adult specimens of P. brasilianus were examined for parasites. Temporal variability in parasite burdens was assessed from fish caught seasonally in coastal waters of two zones, south Bonaerense (during autumn and winter) and north Bonaerense (during summer). Additional data from a previous study, comprising P. brasilianus caught during spring in these two zones, as well as in two populations from north Patagonian gulfs were used for comparative analyses of spatial variability. A total of 14 193 metazoan parasites belonging to 19 species were found. Comparisons of seasonal variability in pooled samples and within each locality showed that locality effects exceeded seasonal ones, suggesting the possible existence of two discrete stocks in the Bonaerense region. These findings were strongly supported by discriminant analyses and comparisons of prevalence and abundance between zones, after pooling seasonal samples within each zone. Further evidence of the discreteness of both stocks was assessed by inclusion of samples from Patagonian gulfs in the discriminant analysis, confirming that their differences were at a inter-population level. The parasite species that contributed most to the separation of the samples were generally those identified as biological markers in previous studies. Differing oceanographic conditions are discussed as potential causes of inter-population variation of parasite burdens.     

Parasites of Cynoscion guatucupa along South American Atlantic coasts: evidence for stock discrimination

Two stocks of striped weakfish Cynoscion guatucupa in the south‐west Atlantic Ocean, were identified using parasites as biological tags. A total of 297 fish caught in Brazil, Uruguay and Argentina, contained 29 species of metazoan parasites. Univariate analysis on parasite populations, as well as multivariate discriminant analysis, calculated for juvenile and adult fish separately, allowed the identification of the two stocks, one from Argentina and Uruguay and the other from Brazil, to be made. Southern samples were characterized by higher prevalences and abundance of larval endohelminths, whereas in the northern stock, gastrointestinal and ectoparasitic species were common. Discriminant analyses on parasite infracommunities of Brazilian fish showed notable differences between juvenile and adult hosts; no such trend was observed in fish from Argentina and Uruguay, despite differences between juveniles and adults at the population level. Different oceanographic conditions and their influence on the distribution of parasites as well as of other hosts involved in their life cycles could be key factors for the differences observed among stocks of C. guatucupa .     

THE CORRELATION OF APHID NUMBERS WITH THE SPREAD OF LEAF ROLL AND RUGOSE MOSAIC IN POTATO CROPS

An analysis of the results of experiments in different parts of England and Wales from 1941 to 1947 on the spread of potato leaf roll and rugose mosaic showed that leaf roll spread was correlated with the number of alate Myzus persicae (Sulzer) caught on sticky traps throughout the potato-growing season; there was some correlation with the maximum count of M. persicae per 100 leaves, but this possibly results from the correlation between trapped aphids and the number per 100 leaves. Spread of rugose mosaic (potato virus Y) was correlated to a lesser degree with number of M, persicae , perhaps because other aphid species are often vectors. With both diseases higher correlations were obtained when the infected plants were dispersed among the healthy crop than when they were placed together in a row. It is concluded that it is possible to predict the average health of potato stocks in the following year from average trap data; further work may enable the health of individual stocks to be predicted.     

Quantitative Genetics of Postponed Aging in Drosophila Melanogaster. II. Analysis of Selected Lines

Quantitative genetic analyses of Drosophila melanogaster stocks with postponed aging have suffered from the problem of a lack of certainty concerning patterns of allelic differentiation. The present experiments were designed to alleviate this difficulty by selecting for enhanced levels of characters known to be related to postponed aging. Selection successfully increased the degree of differentiation of postponed aging stocks with respect to starvation resistance and fecundity, but persistent additive genetic variance suggested that selection did not result in fixation of alleles. The artificially selected stocks were subjected to crosses to test for patterns of dominance and maternal effects. There was little evidence for these effects in the inheritance of the characters underlying postponed aging, even with the increased differentiation of the selected stocks.     

Genetic structure and diversity of Japanese kokanee Oncorhynchus nerka stocks as revealed by microsatellite and mitochondrial DNA markers

Genetic structure and diversity of nine Japanese kokanee (landlocked) Oncorhynchus nerka stocks and anadromous O. nerka from the North Pacific and the Canadian Lake Cultus population were examined using microsatellite and mitochondrial DNA. Sequence analyses of the cytochrome b region of mtDNA for Japanese kokanee O. nerka stocks on Honshu and Hokkaido islands revealed that most Japanese stocks were monomorphic of one major haplotype, which was also dominant in the Lake Cultus population and anadromous O. nerka in the North Pacific. Assignment tests using microsatellite DNA revealed that there was no clear-cut population structure in Japanese kokanee O. nerka stocks.     

Trait‐based climate vulnerability assessments in data‐rich systems: An application to eastern Bering Sea fish and invertebrate stocks

Trait‐based climate vulnerability assessments based on expert evaluation have emerged as a rapid tool to assess biological vulnerability when detailed correlative or mechanistic studies are not feasible. Trait‐based assessments typically view vulnerability as a combination of sensitivity and exposure to climate change. However, in some locations, a substantial amount of information may exist on system productivity and environmental conditions (both current and projected), with potential disparities in the information available for data‐rich and data‐poor stocks. Incorporating this level of detailed information poses challenges when conducting, and communicating uncertainty from, rapid vulnerability assessments. We applied a trait‐based vulnerability assessment to 36 fish and invertebrate stocks in the eastern Bering Sea (EBS), a data‐rich ecosystem. In recent years, the living marine resources of the EBS and Aleutian Islands have supported fisheries worth more than US $1 billion of annual ex‐vessel value. Our vulnerability assessment uses projections (to 2039) from three downscaled climate models, and graphically characterizes the variation in climate projections between climate models and between seasons. Bootstrapping was used to characterize uncertainty in specific biological traits and environmental variables, and in the scores for sensitivity, exposure, and vulnerability. The sensitivity of EBS stocks to climate change ranged from “low” to “high,” but vulnerability ranged between “low” and “moderate” due to limited exposure to climate change. Comparison with more detailed studies reveals that water temperature is an important variable for projecting climate impacts on stocks such as walleye pollock (Gadus chalcogrammus), and sensitivity analyses revealed that modifying the rule for determining vulnerability increased the vulnerability scores. This study demonstrates the importance of considering several uncertainties (e.g., climate projections, biological, and model structure) when conducting climate vulnerability assessments, and can be extended in future research to consider the vulnerability of user groups dependent on these stocks.     

Lack of trophic competition among wild and hatchery juvenile chum salmon during early marine residence in Taku Inlet,Southeast Alaska

Early marine trophic interactions of wild and hatchery chum salmon (Oncorhynchus keta) were examined as a potential cause for the decline in harvests of adult wild chum salmon in Taku Inlet, Southeast Alaska. In 2004 and 2005, outmigrating juvenile chum salmon were sampled in nearshore habitats of the inlet (spring) and in epipelagic habitat at Icy Strait (summer) as they approached the Gulf of Alaska. Fish were frozen for energy density determination or preserved for diet analyses, and hatchery stocks were identified from the presence of thermal marks on otoliths. We compared feeding intensity, diets, energy density, and size relationships of wild and hatchery stocks (n = 3123) across locations and weeks. Only hatchery fish feeding intensity was negatively correlated with fish abundance. In both years, hatchery chum salmon were initially larger and had greater energy density than wild fish, but lost condition in early weeks after release as they adapted to feeding on wild prey assemblages. Diets differed between the stocks at all inlet locations, but did not differ for hatchery salmon between littoral and neritic habitats in the outer inlet, where the stocks overlapped most. Both diets and energy density converged by late June. Therefore, if density-dependent interactions affect wild chum salmon, these effects must be very rapid because survivors in Icy Strait showed few differences. Our study also demonstrates that hatchery release strategies used near Taku Inlet successfully promote early spatial segregation and prey partitioning, which reduce the probability of competition between wild and hatchery chum salmon stocks.     

大兴安岭和长白山地区蜜环菌生物种的研究

从大兴安岭和长白山采集到30号蜜环菌(Armillaria mellea)标本,选其中有代表性的10个号的担子果获得单孢株。交配试验表明每一担子果都具有双因子异宗配合系。不同子实体交配型之间交配结果表明,在大兴安岭和长白山地区蜜环菌目前至少存在5个生物种,分别称为生物种A、B、C、D和E。将这5个生物种的单孢菌种与欧洲5个蜜环菌生物种的单孢菌株进行配合,生物种B与欧洲A.gallica,生物种E与欧洲A.ostoyae亲和交配,因此将生物种B和E分别定为A.gallica和A.ostoyae。生物种A、C和D则不与任何欧洲生物种交配。     

Above- and Below-Ground Carbon Stocks in an Indigenous Tree (Mytilaria laosensis) Plantation Chronosequence in Subtropical China

More than 60% of the total area of tree plantations in China is in subtropical, and over 70% of subtropical plantations consist of pure stands of coniferous species. Because of the poor ecosystem services provided by pure coniferous plantations and the ecological instability of these stands, a movement is under way to promote indigenous broadleaf plantation cultivation as a promising alternative. However, little is known about the carbon (C) stocks in indigenous broadleaf plantations and their dependence on stand age. Thus, we studied above- and below-ground biomass and C stocks in a chronosequence of Mytilaria laosensis plantations in subtropical China; stands were 7, 10, 18, 23, 29 and 33 years old. Our assessments included tree, shrub, herb and litter layers. We used plot-level inventories and destructive tree sampling to determine vegetation C stocks. We also measured soil C stocks by analyses of soil profiles to 100 cm depth. C stocks in the tree layer dominated the above-ground ecosystem C pool across the chronosequence. C stocks increased with age from 7 to 29 years and plateaued thereafter due to a reduction in tree growth rates. Minor C stocks were found in the shrub and herb layers of all six plantations and their temporal fluctuations were relatively small. C stocks in the litter and soil layers increased with stand age. Total above-ground ecosystem C also increased with stand age. Most increases in C stocks in below-ground and total ecosystems were attributable to increases in soil C content and tree biomass. Therefore, considerations of C sequestration potential in indigenous broadleaf plantations must take stand age into account.     

Lack of correlation between in vitro susceptibility to Benznidazole and phylogenetic diversity of Trypanosoma cruzi, the agent of Chagas disease

Chagas disease remains an important health problem in Central and South America. Nitroimidazole derivative drugs like Benznidazole are commonly used to treat Trypanosoma cruzi infection. Natural variation of drug susceptibility between various T. cruzi stocks has been proposed as a possible explanation of treatment failure. Thus, the aim of this work was to determine potential correlations between in vitro Benznidazole susceptibility of different T. cruzi stocks and their genetic diversity. For this purpose, 16 natural stocks representing the overall genetic diversity of the parasite were analysed. Genetic characterisation was assessed by both random amplified polymorphic DNA (RAPD) and multilocus enzyme electrophoresis (MLEE) analyses. Drug activity was determined by two complementary methods, the MTT-PMS micro-method and FACs analysis. The 50% inhibitory concentrations (IC(50)s) were determined. Important variation of IC(50) values (7.3-16.9 microM) among stocks belonging to different discrete typing units (DTUs) was recorded. Further, correlation analysis showed that natural susceptibility to Benznidazole in T. cruzi expressed as IC(50) level was not related with its genetic structure represented by the different DTUs. These results are discussed in relation with the proposed hypothesis establishing a link between genetic diversity and biological behaviour in T. cruzi.     

不同的栽培技术措施对银杏苗木生长的影响

通过苗圃栽培试验,研究了不同栽培技术条件下苗木的生物量,对比了施肥、断胚根、遮荫等技术措施的效果,并用析因试验的方法进行分析,认为关键性技术措施是重施基肥。     

Using historical captive stocks in conservation. The case of␣the␣lesser white-fronted goose

Many captive stocks of economically or otherwise valuable species were established before the decline of the wild population. These stocks are potentially valuable sources of genetic variability, but their taxonomic identity and actual value is often uncertain. We studied the genetics of captive stocks of the threatened lesser white-fronted goose Anser erythropus maintained in Sweden and elsewhere in Europe. Analyses of mtDNA and nuclear microsatellite markers revealed that 36% of the individuals had a hybrid ancestry. Because the parental species are closely related it is unlikely that our analyses detected all hybrid individuals in the material. Because no ancestral polymorphism or introgression was observed in samples of wild populations, it is likely that the observed hybridisation has occurred in captivity. As a consequence of founder effect, drift and hybridisation, captive stocks were genetically differentiated from the wild populations of the lesser white-fronted goose. The high level of genetic diversity in the captive stocks is explained at least partially by hybridisation. The present captive stocks of the lesser white-fronted goose are considered unsuitable for further reintroduction, or supplementation: hybridisation has involved three species, the number of hybrids is high, and all the investigated captive stocks are similarly affected. The results highlight the potential shortcomings of using captive-bred individuals in supplementation and reintroduction projects, when the captive stocks have not been pedigreed and bred according to conservation principles. Deceased 20 March 2004.     

Biodiversity in species,traits, and structure determines carbon stocks and uptake in tropical forests

Impacts of climate change require that society urgently develops ways to reduce amounts of carbon in the atmosphere. Tropical forests present an important opportunity, as they take up and store large amounts of carbon. It is often suggested that forests with high biodiversity have large stocks and high rates of carbon uptake. Evidence is, however, scattered across geographic areas and scales, and it remains unclear whether biodiversity is just a co‐benefit or also a requirement for the maintenance of carbon stocks and uptake. Here, we perform a quantitative review of empirical studies that analyzed the relationships between plant biodiversity attributes and carbon stocks and carbon uptake in tropical forests. Our results show that biodiversity attributes related to species, traits or structure significantly affect carbon stocks or uptake in 64% of the evaluated relationships. Average vegetation attributes (community‐mean traits and structural attributes) are more important for carbon stocks, whereas variability in vegetation attributes (i.e., taxonomic diversity) is important for both carbon stocks and uptake. Thus, different attributes of biodiversity have complementary effects on carbon stocks and uptake. These biodiversity effects tend to be more often significant in mature forests at broad spatial scales than in disturbed forests at local spatial scales. Biodiversity effects are also more often significant when confounding variables are not included in the analyses, highlighting the importance of performing a comprehensive analysis that adequately accounts for environmental drivers. In summary, biodiversity is not only a co‐benefit, but also a requirement for short‐ and long‐term maintenance of carbon stocks and enhancement of uptake. Climate change policies should therefore include the maintenance of multiple attributes of biodiversity as an essential requirement to achieve long‐term climate change mitigation goals.