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.     

Urban Metabolism and the Energy Stored in Cities

Using the city of Toronto as a case study, this article examines impacts of energy stocks and flexible demand in the urban metabolism on the resilience of the city, including discussion of directions for further study of the resiliency of the urban metabolism. An important element developed is the nominal residence time of the energy stocks. This value defines how long an energy stock lasts under typical patterns of energy use. The findings suggest that the residence times of many sources of energy overcome vulnerability when energy supply shocks last on the order of hours or a few days, but that the measure is limited to assessing only certain types of commonly used energy sources in aggregate terms. Discussion is included on the uncertainty of this measure and on the metabolic and resiliency implications of new technologies intended to reduce energy use and improve sustainability of cities and the use of the urban metabolism as a means of comparison. The methodology employed highlights how waste energy could be used to increase the resiliency of the city's water supply, but also how the study of the urban metabolism would benefit from a more disaggregate form in the study of sustainable and resilient cities.     

Similarities of Giardia antigens derived from human and animal sources

A total of 37 Giardia stocks isolated from humans and 14 stocks derived from animal sources have been analysed for antigenic differences. Separation of the proteins of the stocks by polyacrylamide gel electrophoresis showed no major differences among the stocks. Immunoblotting of these antigens demonstrated some minor differences which were not correlated with geographic location, allozyme type, virulence or any other distinguishing characteristic of the stocks. Immunofluorescence tests using monoclonal antibodies revealed some differences between stocks but the monoclonal antibodies did not significantly inhibit growth in inhibition assays.     

Geographic variation in Giardia karyotypes

Chromosomes of 41 stocks of Giardia duodenalis derived from humans and 14 stocks from other animal species were analysed by field inversion gel electrophoresis (FIGE). These stocks have two predominant karyotypes as judged by FIGE which appear to fit a geographic distribution. Under FIGE conditions used to optimize the detection of size variation in Giardia chromosomes, five or six major chromosomes could be identified. Most of the stocks derived from North America have three major chromosomes smaller than 800 kb while most of the Australian stocks have four. A few exceptions, and minor variations, of these karyotypes were observed. It was estimated that not all of the DNA entered the gel, the remainder being trapped conformations or very large chromosomes. Karyotypes of Giardia stocks from different animal hosts and human sources within a geographical region are similar.     

Tracing carbon sources in small urbanising streams: catchment‐scale stormwater drainage overwhelms the effects of reach‐scale riparian vegetation

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Using hierarchical models to estimate effects of ocean anomalies on north-west Pacific Chinook salmon Oncorhynchus tshawytscha recruitment

The high variability in survival over the past three decades of north-west Pacific Chinook salmon Oncorhynchus tshawytscha is summarized for 24 stocks and analysed using hierarchical Bayesian models. Results from a simple model indicate that recruitment anomalies appear to be correlated in time and space. A simple model with a covariate based on basin-scale effects (Pacific Decadal Oscillation and El Ni?o Southern Oscillation) and local-scale effects (sea surface temperature, SST anomaly) was introduced to explain this variability. The model still exhibited residual patterns that were removed when a random-walk component was added to the model. The analysis indicates that recruitment is negatively related to SST anomaly for all stocks and the effect of basin-scale variables is negligible. The effect of climate over the next century is expected to result in estimated recruitment declining by an average of 13% for O. tshawytscha stocks coastwide.     

Carbon storage in terrestrial ecosystems: do browsing and grazing herbivores matter?

Large mammalian herbivores manifest a strong top‐down control on ecosystems that can transform entire landscapes, but their impacts have not been reviewed in the context of terrestrial carbon storage. Here, we evaluate the effects of plant biomass consumption by large mammalian herbivores (>10 kg adult biomass), and the responses of ecosystems to these herbivores, on carbon stocks in temperate and tropical regions, and the Arctic. We calculate the difference in carbon stocks resulting from herbivore exclusion using the results of 108 studies from 52 vegetation types. Our estimates suggest that herbivores can reduce terrestrial above‐ and below‐ground carbon stocks across vegetation types but reductions in carbon stocks may approach zero given sufficient periods of time for systems to respond to herbivory (i.e. decades). We estimate that if all large herbivores were removed from the vegetation types sampled in our review, increases in terrestrial carbon stocks would be up to three orders of magnitude less than many of the natural and human‐influenced sources of carbon emissions. However, we lack estimates for the effects of herbivores on below‐ground biomass and soil carbon levels in many regions, including those with high herbivore densities, and upwards revisions of our estimates may be necessary. Our results provide a starting point for a discussion on the magnitude of the effects of herbivory on the global carbon cycle, particularly given that large herbivores are common in many ecosystems. We suggest that herbivore removal might represent an important strategy towards increasing terrestrial carbon stocks at local and regional scales within specific vegetation types, since humans influence populations of most large mammals.     

Intra-and interchromosomal effects of heterozygous inversions on recombination in the third chromosome of Drosophila ananassae

In order to study intra-and interchromosomal effects of heterozygous inversions on recombination in the third chromosome of D.ananassae, experiments were conducted using Stw-pr marker stock and five wild stocks with known karyotypes. The stocks used were homozygous for standard or inverted gene sequence in 2L, 3L, and 3R. Recombination was investigated in both sexes. There was complete absence of crossing-over in males in all the experiments which appeared to be the characteristic of marker stock as spontaneous male crossing-over was reported earlier with the same wild stocks when the second chromosome markers were used. Based on the data of karyotypically homozygous F1 females, the map distance between stw-pr was 36.55 map units. The heterozygosity due to a lengthy inversion in 2L increased the level of crossing-over between stw-pr genes of the third chromosome indicating interchromosomal effect. There was a considerable reduction in the rate of recombination between the same markers due to inversion heterozygosity in 3R indicating intrachromosomal effect. However, 3L inversion heterozygosity had no effect on crossover rate. These results provide evidence for intra-and interchromosomal effects of inversions on crossing-over in the third chromosome of D. ananassae.     

Complexation with chondroitin sulfate C and Polybrene rapidly purifies retrovirus from inhibitors of transduction and substantially enhances gene transfer

Using amphotropic retrovirus stocks produced by TELCeB6-A cells that encode the Escherichia coli lacZ gene, we found that complexation with chondroitin sulfate C (CSC) and Polybrene (PB) is an effective means to purify retrovirus. Virus stocks contained high levels of inhibitory activity that blocked amphotropic, but not ecotropic, retrovirus transduction. When virus stocks were brought to 80 microg/mL each of CSC and PB, complexes of CSC and PB formed. These complexes incorporated more than 70% of the virus particles but less than 0.4% of all other proteins and no detectable inhibitory activity. Purified virus transduced NIH 3T3 murine fibroblasts 21 to 186-fold more efficiently than virus that was not purified. In addition, virus purification significantly altered the dose response of transduction. When virus that had not been purified was used to transduce cells, the relationship between transduction and virus concentration was highly non-linear. In contrast, when purified virus was used, transduction increased monotonically and was linearly proportional to virus concentration, except when high doses of virus were used. Interestingly, when high doses of virus were used gene transfer reached a maximum plateau level, most likely because particle-associated amphotropic envelope proteins had saturated the cellular receptors for the virus. Our findings illustrate that retrovirus purification increases the maximum number of genes that can be transferred, reduces the amount of virus required to achieve a given level of gene transfer, and reduces uncertainties about the relationship between the amount of virus used and the number of genes transferred.     

Substantial loss of genetic variation in a single generation of Senegalese sole (Solea senegalensis) culture: implications in the domestication process

The flatfish Solea senegalensis represents an important resource in modern mariculture and is largely raised in South Spain and Portugal. Substantial progress has been achieved in its domestication, though suitable reproduction and zootechnical conditions still remain unknown. Difficulties to obtain breeders from wild lead many companies to set up broodstocks with first generation (G1) progeny without genetic guidelines. To study the genetic processes underlying the early stage of domestication of this species, the genetic structure of four representative broodstocks from Southern Spain has been assessed by means of eight microsatellite loci . Data revealed a substantial reduction in levels of genetic variability on just one generation in stocks totally or partially composed of G1 individuals when compared with those solely integrated by individuals from wild. The genetic relatedness within the four stocks has been established, having detected close relationships between individuals from cultured origin, thus suggesting that the loss of variability is apparently due to setting up broodstocks by blind selecting of family related G1 individuals. The high proportion of siblings in these stocks can have negative consequences in future generations due to inbreeding effects. The relationships between the four broodstocks were traced, having found a common origin between two of them, which come from the same donor hatchery, thus enhancing the homogenization of the existent resources for S. senegalensis among the various stocks. This finding alerts about the risks in exchanging fish between hatcheries without knowing their genetic origin. From this study, the use of microsatellites is strongly recommended to control the genetic composition of S. senegalensis broodstocks, aimed to maintain standards of genetic health and improve their reproduction capacity, which is a key issue in the domestication process.     

Genetic analysis of growth and maturity in pink salmon (Oncorhynchus gorbuscha)

Variation in growth and sexual maturity was examined for five stocks of pink salmon (Oncorhynchus gorbuscha) spawning at different times in British Columbia. In each stock, four males were mated with eight females in a nested breeding design, and the juveniles were reared for 500 d after fry emergence. Adults in early-spawning northern stocks were smaller than those in late-spawning southern ones, but pink salmon from northern stocks had faster growth rates than those from southern ones. The relative ranking within stocks of family weight remained constant after late winter in the year of maturity. Heritability of weight based upon sire variance components was usually greater than 0.9 after 150 d of rearing. Pink salmon from the earlier-spawning stocks were in a more advanced state of sexual maturity when the experiment was terminated than were those from later-spawning stocks, indicative of a significant genetic component in timing of sexual maturity.     

Improved baculovirus vectors expressing barnase using promoters from Cotesia plutellae bracovirus

The goal of this study was to create a novel baculovirus expression system that does not require recombinant virus purification steps. Transfection of insect cells with transfer vectors containing barnase under control of the Cotesia plutellae bracovirus (CpBV) promoters ORF3004 or ORF3005 reduced cell growth. Co-transfection with bApGOZA DNA yielded no recombinant viruses and non-recombinant backgrounds. To further investigate the detrimental effects of barnase on insect cells, two recombinant bacmids harboring the barnase gene under control of the CpBV promoters, namely bAcFast-3004ProBarnase and bAcFast-3005ProBarnase, were constructed. While no viral replication was observed when only the recombinant bacmids were transfected, recombinant viruses were generated when the bacmids were co-transfected with the transfer vector, pAcUWPolh, through substitution of the barnase gene with the native polyhedrin gene by homologous recombination. Moreover, no non-recombinant backgrounds were detected from unpurified recombinant stocks using PCR analysis. These results indicate that CpBV promoters can be used to improve baculovirus expression vectors by means of lethal gene expression under the control of these promoters.     

Geographical and intrapopulation variation in the diet of a threatened marine predator,Pontoporia blainvillei (Cetacea)

Understanding diet variation is a major concern when developing conservation guidelines for threatened species, especially for marine predators whose prey availability can be reduced by commercial fisheries. Diet can vary in geographically structured populations due to variation in prey availability and within a location due to the effects of season, sex, age, and individual. However, these sources of variation are seldom considered together in dietary studies. We analyzed diet variation at the geographical and intrapopulation levels in the franciscana dolphin (Pontoporia blainvillei) by analyzing samples of stomach contents from individuals incidentally caught by artisanal fisheries. We investigated the geographical (Northern, Central, and Southern regions of the São Paulo State coast, Brazil) and intrapopulation effects of season, sex, and age. We used the leave‐one‐out cross‐validation method to test for significance of the proportional similarity index, which measures the overlap between diet compositions. We found that diet varied across different levels, from the geographical to the individual level, including the effects of season, sex, and age. Diet variation as a function of age suggests an ontogenetic diet shift. Our findings indicate that ecological processes within local stocks should inform management at the local geographic scale. Evidence for ecological differences between franciscana stocks is of great significance for the conservation of this threatened species.     

Changes of Structure and Stock in Exploited Fish Communities in Estuaries of the Southern Baltic Coast (Mecklenburg-Vorpommern,Germany)

By means of analyses of catch values of selected fish species possible effects of eutrophication on the estuaries are described. Although the registered stock changes are not only a result of eutrophication a stock increase in pikeperch could be verified at the end of the first half of this century. With progressive eutrophication a great decline of migratory fish stocks took place at the end of the sixties/beginning of the seventies. The decline of eel stocks is not caused by eutrophication. Afterwards pike stocks show an aggravating decline in hypertrophic estuaries which are related to the decline of macrophytes. Baltic whitefish has still kept up its stock level under these conditions. Symptoms for a growing danger of an unexpected disaster are increasing to the whole fish community of extremely polluted waters.     

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.     

Trypanosoma brucei rhodesiense: characterisation of stocks from Zambia, Kenya, and Uganda using repetitive DNA probes

We have previously described a system for characterising the relationships between trypanosome stocks of the T.brucei group based on Southern blotting with repetitive DNA probes followed by cluster analysis of resultant banding patterns (G. Hide et al. Molec. Bioch. Parasitol. 39, 213-226, 1990). In this study, we extend this analysis to examine the relationships between trypanosome stocks isolated from major sleeping sickness foci in Zambia, Kenya, and Uganda. We show that the trypanosome strains responsible for disease in Zambia are quite distinct from those sampled from the Kenya/Uganda foci. Furthermore, the human serum resistant stocks isolated from the Kenya/Uganda foci which were isolated from man (or from animals) were found to form a tight group in the cluster analysis, while stocks isolated from nonhuman sources in the same area or stocks from elsewhere were found in separate groups. Thus, the human infective trypanosome strains found in these foci may have common origins and have, perhaps, arisen by clonal selection from a common source.     

Modelling the patterns of dispersion of length at age in teleost fishes

The patterns of dispersion of length at age were analysed in 142 samples representing 115 stocks, 72 species and seven orders of teleost fishes. The coefficients of variation i.e. the ratios of the standard deviations to the mean lengths, declined with age in 85 samples, did not vary significantly with age in 50 samples and increased with age in seven samples. A rapid exponential decline in the coefficients of variation of length with age was a dominant characteristic of most short-lived stocks. Conversely, in most long-lived stocks, the coefficients of variation of length remained relatively constant, declined gradually, or increased slightly with age. It is proposed that the patterns of dispersion of length at age can be modelled empirically as a function of longevity. The probable sources of the observed patterns, including the intrinsic variability of life-history parameters between individuals and the impact of social interactions, are discussed.     

Synchronous patterns of fluctuations in two stocks of anchovy Engraulis ringens Jenyns, 1842 in the Humboldt Current System

Most of the studies investigating synchrony in fluctuations of abundance of small pelagic fish have been based on catch data only, which do not describe the dynamics of populations as a relative abundance index. In this paper, catch, biomass, recruitment and recruitment rate, were used to compare synchronous changes for two stocks of anchovy (Engraulis ringens) from 1982 to 2004. One is the North Central Peru stock (NCP) and the other is the shared South Peru‐Northern Chile stock (SPNC). Correlation analysis demonstrated a significant association between population time series, particularly during the growing phase of the stocks. Thus, the synchronous fluctuation pattern of the two stocks is due to the recovery phase and probably driven by density‐independent effects of simultaneous favorable environmental conditions occurring in the two regions. The conclusions were: (i) both NCP and SPNC anchovy stocks are in an overall positive phase of synchrony, (ii) higher correlations in the synchronous pattern of fluctuations occurred during simultaneous increase of biomass, and (iii) short‐term fluctuations were negative when the abundance of the stock was lower and/or impacted by El Niño events.     

The impact of black wattle encroachment of indigenous grasslands on soil carbon,Eastern Cape,South Africa

Black wattle (Acacia mearnsii, De Wild.) is a fast growing tree species introduced into South Africa in the nineteenth century for commercial purposes. While being an important source of timber and firewood for local communities, black wattle is an aggressive invasive species and has pervasive adverse environmental impacts in South Africa. Little is known about the effects of black wattle encroachment on soil carbon, therefore the aim of this study was to investigate the impact of black wattle encroachment of natural grassland on soil carbon stocks and dynamics. Focussing on two sites in the Eastern Cape, South Africa, the study analysed carbon stocks in soil and litter on a chronosequence of black wattle stands of varying ages (up to >50 years) and compared these with adjacent native grassland. The study found that woody encroachment of grassland at one site had an insignificant effect on soil and litter carbon stocks. The second site showed a clear decline in combined soil and litter carbon stocks following wattle encroachment. The lowest stock was in the oldest wattle stand, meaning that carbon stocks are still declining after 50 years of encroachment. The results from the two sites demonstrate the importance of considering changes in soil carbon when evaluating ecosystem effects of invasive species.     

Anti-progesterone monoclonal antibody affects early cleavage and implantation in the mouse by mechanisms that are influenced by genotype

Pregnancy was blocked by anti-progesterone monoclonal antibody in two inbred (BALB/cJ, CBA/Ca) but to a lesser degree in an F1 hybrid (CBA/Ca male X BALB/cJ female) or an outbred (Tuck's no. 1) stock of mice when antibody was injected intraperitoneally (i.p.) at 32 h post coitum (p.c.) using a dosage of 9.5-10.9 nmol. This different antifertility effect could not be explained solely by altered tubal transport in inbred mice since the rate of transport was slightly accelerated in one stock (BALB/c) but not in another (CBA). In crossbred mice tubal transport was not significantly altered by antibody treatment. At Day 3 (54-58 h p.c.), the majority of embryos in control mice were at the 4-cell and 8-cell to morula stages in inbred and crossbred stock, respectively, but after antibody treatment they were mainly at the 4-cell stage in all 4 stocks. At Day 4 (78-82 h p.c.) the majority of embryos in control females had reached the blastocyst stage in all stocks, whereas after antibody treatment they had reached this stage in crossbred stock and relatively few had progressed so far in inbred stock. The results indicate that there are two events in early gestation which are susceptible to passive immunization with anti-progesterone monoclonal antibody. The first of these occurs during cleavage shortly after the 4-cell stage when embryo development was arrested in two inbred stocks of mice. Antibody effects on cleavage were not direct since embryos cultured in the presence of high concentrations of antibody, or antibody saturated with progesterone, continued to develop in the normal way and formed blastocysts. The second event is the onset of implantation, an effect also influenced by genotype. The decidual cell reaction induced by intraluminal oil injection was blocked by antibody injected at 8 or 32 h p.c. in BALB/c females, but only when injected at 8 h, and not at 32 h p.c., in F1 hybrid females. The results show that there is a greater resistance in two crossbred stocks compared with two inbred stocks to the effects of passive immunization against progesterone in early pregnancy.