Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Colonies

  • american colony
  • ant colony
  • aphid colony
  • australian colony
  • bacterial colony
  • bee colony
  • breeding colony
  • british colony
  • bumblebee colony
  • captive colony
  • cell colony
  • cfu-gm colony
  • control colony
  • different colony
  • erythroid colony
  • fungal colony
  • greek colony
  • honey bee colony
  • honeybee colony
  • host colony
  • individual colony
  • insect colony
  • laboratory colony
  • large colony
  • maternity colony
  • mature colony
  • mixed colony
  • natal colony
  • neighbouring colony
  • nesting colony
  • new colony
  • same colony
  • seabird colony
  • single colony
  • small colony
  • yeast colony

  • Terms modified by Colonies

  • colony algorithm
  • colony characteristic
  • colony count
  • colony counting
  • colony decreased
  • colony density
  • colony form
  • colony formation
  • colony founding
  • colony genetic structure
  • colony growth
  • colony growth rate
  • colony hybridization
  • colony level
  • colony member
  • colony morphology
  • colony number
  • colony optimization
  • colony productivity
  • colony sex ratio
  • colony site
  • colony size
  • colony stimulating factor
  • colony stimulation factor

  • Selected Abstracts


    ABSTRACT. Pogroms in the Russian Pale in 1881 set off a wave of immigration of Russian Jews to the United States. Most went to the cities, but an important group, with the support of philanthropic organizations, became part of an experiment in Jewish agricultural colonies. South Jersey's Alliance and Woodbine were the most successful. Both were established on undeveloped land, and the landscape that emerged suggests the importance the funders placed on using landscape as a means of Americanization. [source]


    JOURNAL OF PHYCOLOGY, Issue 1 2004
    Malcolm Potts
    No abstract is available for this article. [source]


    Summary. There have been recent suggestions that an indigenous element in ancient Greek settlements in Sicily can be detected through funerary customs. This paper reviews the evidence for ,indigenous' burial methods in Greek cemeteries, concentrating on multiple, contracted and acephalous burials. It argues that such evidence is limited and open to various interpretations and that while it is highly likely that Greek settlements did incorporate an indigenous population, the funerary record cannot be used as a reliable identifier of such groups. The paper also briefly assesses the evidence for the presence of Greeks deriving from areas other than the historical mother-cities and suggests that such individuals are also very difficult to detect. It concludes that the general impression given by Sicilian Greek cemeteries is one of overall subscription to coherent burial systems, which may be viewed as part of an attempt to forge a unified and independent cultural identity. [source]

    Integration and differentiation of human embryonic stem cells transplanted to the chick embryo

    Ronald S. Goldstein
    Abstract Human embryonic stem (ES) cells are pluripotent cells that can differentiate into a large array of cell types and, thus, hold promise for advancing our understanding of human embryology and for contributing to transplantation medicine. In this study, differentiation of human ES cells was examined in vivo by in ovo transplantation to organogenesis-stage embryos. Colonies of human ES cells were grafted into or in place of epithelial-stage somites of chick embryos of 1.5 to 2 days of development. The grafted human ES cells survived in the chick host and were identified by vital staining with carboxyfluorescein diacetate or use of a green fluorescent protein,expressing cells. Histologic analysis showed that human ES cells are easily distinguished from host cells by their larger, more intensely staining nuclei. Some grafted cells differentiated en masse into epithelia, whereas others migrated and mingled with host tissues, including the dorsal root ganglion. Colonies grafted directly adjacent to the host neural tube produced primarily structures with the morphology and molecular characteristics of neural rosettes. These structures contain differentiated neurons as shown by ,-3-tubulin and neurofilament expression in axons and cell bodies. Axons derived from the grafted cells penetrate the host nervous system, and host axons enter the structures derived from the graft. Our results show that human ES cells transplanted in ovo survive, divide, differentiate, and integrate with host tissues and that the host embryonic environment may modulate their differentiation. The chick embryo, therefore, may serve as an accessible and unique experimental system for the study of in vivo development of human ES cells. © 2002 Wiley-Liss, Inc. [source]

    Developmental changes in factors limiting colony survival and growth of the leaf-cutter ant Atta laevigata

    ECOGRAPHY, Issue 3 2010
    Ernane H. M. Vieira-Neto
    Many species of leaf-cutter ants (Atta and Acromyrmex) increase in abundance following natural or anthropogenic disturbances in the vegetation. However, the mechanisms responsible for such an increase are still poorly understood. We evaluated the effects of nesting site and the availability of palatable forage on survival and growth of Atta laevigata colonies at different developmental stages. Foundress queens transplanted into man-made clearings (dirt roads) had a much higher survival than those transplanted into the adjacent undisturbed savannah vegetation. Similarly, incipient colonies (,3-months old) had significantly greater survival and growth rates in dirt roads. In contrast, nesting site did not influence performance of young colonies (,15-months old). Both incipient and young colonies responded strongly and positively to experimental supplementation of palatable forage, and this effect was independent of the nesting habitat. Colonies that received extra food grew faster and had a significantly greater survival rate than control colonies. These results suggest that performance of A. laevigata is affected by the generally greater availability of suitable nesting sites and palatable vegetation in disturbed habitats. This may explain how these ants maintain high densities in these habitats, and since the relative importance of these factors changed with colony ontogeny, our findings highlight the importance of evaluating potential limiting factors throughout the full range of an organism's developmental stages. [source]

    Seasonal spatial dynamics and causes of nest movement in colonies of the invasive Argentine ant (Linepithema humile)

    Abstract 1.,Colony organisation and movement behaviour of the Argentine ant (Linepithema humile) was studied over 3 years in field populations in California and in captive colonies in the laboratory. This invasive species is highly polydomous and unicolonial; colonies consist of expansive and fluid networks of nests and trails. The spatial and temporal organisation of colonies may contribute to ecological dominance. 2.,Argentine ant nests and inter-nest trails shift in size, abundance, and location, so that colony networks are spatially contracted in the winter and expanded spring to autumn. Colonies occupy permanent sites; ants migrated to and from the same winter nest locations year after year, and occupied 30% of the same nests repeatedly during seasonal migrations. 3.,Nests were moved on average 2,3 m. Forty-two per cent were occupied less than 1 month, 4% the entire study, and the other 54% lasted 3.9 ± 2.3 months (mean ± SD). 4.,Nests were located within 2,4 m of woody plants, in warm sites in the winter and cool sites in the summer. Both humidity and food availability influenced nest-site choice in laboratory colonies. However, when faced with a trade-off between factors, the ants chose humid nest boxes over nest boxes near food, and ants moved nests only in response to changes in humidity and not distance to food. 5.,The results indicate that L. humile colonies are seasonally polydomous, and that nest movements are driven by changes in microclimate. Colony organisation maintains high local density and increases food supply, which may improve the competitive ability of L. humile colonies and reduce opportunities for species coexistence. [source]

    Colony productivity and foundress behaviour of a native wasp versus an invasive social wasp

    Tracy R. Armstrong
    Abstract., 1.,Colony productivity, prey utilisation, and foundress behaviour of a North American native wasp (Polistes fuscatus) versus an European invasive wasp (Polistes dominulus) were investigated in a controlled field experiment with optimal versus natural foraging conditions. Colonies with the optimal prey foraging conditions were provided with prey ad libitum within an enclosed area. The other colonies foraged in the adjacent field,woodland but had the same nest conditions as the other treatment. 2.,When given prey ad libitum, both wasp species captured similar amounts of prey and the conversion to total offspring biomass was similar. But P. dominulus colonies produced 2.5 times the number of workers as P. fuscatus colonies, reflecting the smaller size of P. dominulus wasps. 3.,Foundresses of P. dominulus were observed more often building or repairing the nest, thereby contributing to the production of colonies with twice as many cells as colonies of P. fuscatus. Foundresses of P. dominulus showed more acts of aggression toward workers than did P. fuscatus foundresses, which was not a function of adult density on the nest. 4.,At the end of the experiment, P. dominulus colonies with optimal prey foraging conditions still had a high level of egg-laying and peaked in the number of pupae then, whereas egg-laying and the number of pupae per colony of the other treatments began to decline 2,3 weeks earlier. These results indicate that P. dominulus is more opportunistic than P. fuscatus, which may account in part for P. dominulus's success as an introduced species in North America. [source]

    Spatial patterns, temporal variability, and the role of multi-nest colonies in a monogynous Spanish desert ant

    Xim Cerdá
    Abstract 1.,The colonies of the Spanish desert ant Cataglyphis iberica are polydomous. This study describes the temporal and spatial patterns of the polydomy in this species at two different sites, and presents analyses of its role in reducing the attacks of the queen over sexual brood, and in allowing better habitat exploitation. 2. The spatial distribution of nests was clumped while colonies were distributed randomly. Mean nearest neighbour distance ranged from 3.4 to 7.0 m for nests and from 12.3 to 14.1 m for colonies. Distance of foragers searching for food varied among nests: mean values were between 6.1 and 12.6 m. 3. At both sites, the maximum number of nests per colony occurred in summer, during the maximum activity period of the species. Colonies regrouped at the end of this period but overwintered in several nests. 4. Nest renewal in C. iberica colonies was high and showed great temporal variability: nests changed (open, close, re-open) continuously through the activity season and/or among years. The lifetime of up to 55% of nests was only 1,3 months. 5. Polydomy in C. iberica might decrease the interactions between the queen and the sexual brood. In all colonies excavated just before the mating period, the nest containing the queen did not contain any virgin female. Females were in the queenless nests of the colony. 6. The results also suggest that polydomous C. iberica colonies may enhance habitat exploitation because foraging activity per colony increases with nest number. The relationship between total prey input and foraging efficiency and number of nests per colony attains a plateau or even decreases after a certain colony size (four to six nests). This value agrees with the observed mean number of nests per colony in C. iberica. [source]

    Pollinator genetics and pollination: do honey bee colonies selected for pollen-hoarding field better pollinators of cranberry Vaccinium macrocarpon?

    James H. Cane
    Summary 1. Genetic polymorphisms of flowering plants can influence pollinator foraging but it is not known whether heritable foraging polymorphisms of pollinators influence their pollination efficacies. Honey bees Apis mellifera L. visit cranberry flowers for nectar but rarely for pollen when alternative preferred flowers grow nearby. 2. Cranberry flowers visited once by pollen-foraging honey bees received four-fold more stigmatic pollen than flowers visited by mere nectar-foragers (excluding nectar thieves). Manual greenhouse pollinations with fixed numbers of pollen tetrads (0, 2, 4, 8, 16, 32) achieved maximal fruit set with just eight pollen tetrads. Pollen-foraging honey bees yielded a calculated 63% more berries than equal numbers of non-thieving nectar-foragers, even though both classes of forager made stigmatic contact. 3. Colonies headed by queens of a pollen-hoarding genotype fielded significantly more pollen-foraging trips than standard commercial genotypes, as did hives fitted with permanently engaged pollen traps or colonies containing more larvae. Pollen-hoarding colonies together brought back twice as many cranberry pollen loads as control colonies, which was marginally significant despite marked daily variation in the proportion of collected pollen that was cranberry. 4. Caloric supplementation of matched, paired colonies failed to enhance pollen foraging despite the meagre nectar yields of individual cranberry flowers. 5. Heritable behavioural polymorphisms of the honey bee, such as pollen-hoarding, can enhance fruit and seed set by a floral host (e.g. cranberry), but only if more preferred pollen hosts are absent or rare. Otherwise, honey bees' broad polylecty, flight range, and daily idiosyncrasies in floral fidelity will obscure specific pollen-foraging differences at a given floral host, even among paired colonies in a seemingly uniform agricultural setting. [source]

    Does the diapause experience of bumblebee queens Bombus terrestris affect colony characteristics?

    M. Beekman
    Summary 1. Bumblebee colonies show much variation in the number of workers, drones, and queens produced. Because this variation prevails even when colonies are kept under identical conditions, it does not seem to be caused by extrinsic factors but rather by differences between founding queens. 2. The most likely factor that could cause differences between queens is diapause. Although colonies are raised under standardised conditions, the queens often experience diapause of different length. If there are costs associated with diapause that influence post-diapause reproduction, the diapause history of the queens could affect colony characteristics. 3. Here, several colony characteristics are compared: number of first and second brood workers; total number of workers, drones, and queens; energy spent on sexuals; sex ratio; rate of worker production; time to emergence of first reproductive; and colony lifetime. Colonies were used where the queens experienced a diapause treatment of 0 (nondiapause queens), 2, and 4 months. 4. Although no proof was found for the existence of costs associated with diapause, the colony characteristics of nondiapause queens were significantly different from those of diapause queens. Colonies of nondiapause queens produced the lowest number of workers but the highest number of young queens. 5. It is argued that these nondiapause colonies are more time-constrained than diapause colonies because nondiapause colonies produce two generations within the same season and should therefore be more efficient in producing sexual offspring. 6. Moreover, nondiapause colonies should rear a more female-biased sex ratio because they can be certain of the presence of males produced by other (diapause) colonies. [source]

    Coordinated Development of Yeast Colonies: An Experimental Analysis of the Adaptation to Different Nutrient Concentrations , Part 1

    T. Walther
    Abstract The development of yeast colonies on solid agar substrates served as a model system to investigate the growth of higher fungi in a heterogeneous environment. Applying a new analytical technique , which was based on the estimation of the intensity of transmitted light from microscopic images taken along the colony radius , cell-density distributions inside fungal mycelia were measured at an extremely high spatial resolution. Using this method, the adaptation of yeast colonies to the limitation of different nutrients was investigated. Under conditions of carbon or nitrogen limitation, populations of the dimorphic model yeasts Yarrowia lipolytica and Candida boidinii underwent a transition in their morphology from solid colony to mycelial colony patterns. When grown under conditions that induced the mycelial morphology, colonies extended linearly at a constant rate irrespective of the initial nutrient concentration. In general, the cell density within the population declined at higher degrees of limitation. Nitrogen-limited colonies of both model yeasts, as well as carbon-limited Y.,lipolytica colonies proceeded to extend until the growth field was finally covered by the population. Under these conditions, areas of fairly constant cell densities were formed during the growth process. Only carbon-limited C.,boidinii colonies stopped extending at a final diameter which was small when compared to the size of the growth field, and formed a cell-density profile which was monotonically declining. The observed differences in the final colony diameter, and in the cell-density profile morphology indicated the presence of different regulatory mechanisms that ruled the colony development of the model yeasts. The presented monitoring technique for the biomass distribution inside fungal populations provided the basis for a quantitative and non-invasive description of mycelial development. [source]

    Secondary host generation of the gall aphid Cerataphis jamuritsu (Homoptera)

    Utako KUROSU
    Abstract Colonies of a Cerataphis species with well-developed horns were found on the rattan Calamus quinquesstinervis in southern Taiwan. The morphology of first instar nymphs from the colonies accorded well with the morphology of first instar nymphs laid by alates of Cerataphis jamuritsu from galls on Styrax suberifolia, indicating that the rattan aphids are the secondary host generation of C. jamuritsu. Although the aphid colonies were attended by ants, the sharp horns of the first instar nymphs suggest that they might attack predators. [source]

    Proximate Determinants of Reproductive Skew in Polygyne Colonies of the Ant Formica fusca

    ETHOLOGY, Issue 11 2002
    Minttumaaria Hannonen
    Understanding the determinants of reproductive skew (the partitioning of reproduction among co-breeding individuals) is one of the major questions in social evolution. In ants, multiple-queen nests are common and reproductive skew among queens has been shown to vary tremendously both within and between species. Proximate determinants of skew may be related to both queen and worker behaviour. Queens may attempt to change their reproductive share through dominance interactions, egg eating and by changing individual fecundity. Conversely, workers are in a position to regulate the reproductive output of queens when rearing the brood. This paper investigates queen behaviour at the onset of egg laying and the effect of queen fecundity and worker behaviour on brood development and reproductive shares of multiple queens in the ant Formica fusca. The study was conducted in two-queen laboratory colonies where the queens produced only worker offspring. The results show that in this species reproductive apportionment among queens is not based on dominance behaviour and aggression, but rather on differences in queen fecundity. We also show that, although the queen fecundity at the onset of brood rearing is a good indicator of her final reproductive output, changes in brood composition occur during brood development. Our results highlight the importance of queen fecundity as a major determinant of her reproductive success. They furthermore suggest that in highly derived polygyne species, such as the Formica ants, direct interactions as a means for gaining reproductive dominance have lost their importance. [source]

    In-Hive Behavior of Pollen Foragers (Apis mellifera) in Honey Bee Colonies Under Conditions of High and Low Pollen Need

    ETHOLOGY, Issue 3 2002
    Anja Weidenmüller
    Pollen collection in honey bees is regulated around a homeostatic set-point. How the control of pollen collection is achieved is still unclear. Different feedback mechanisms have been proposed but little is known about the experience of pollen foragers in the hive. A detailed documentation of the behavior of pollen foragers in the hive under different pollen need conditions is presented here. Taking a broad observational approach, we analyze the behavior of individual pollen foragers in the hive between collecting trips and quantify the different variables constituting the in-hive stay. Comparing data from two colonies and 143 individuals during experimentally induced times of low vs. times of high pollen need, we show that individual foragers modulate their in-hive working tempo according to the actual pollen need of the colony: pollen foragers slowed down and stayed in the hive longer when pollen need was low and spent less time in the hive between foraging trips when pollen need by their colony was high. Furthermore, our data show a significant change in the trophallactic experience of pollen foragers with changing pollen need conditions of their colony. Pollen foragers had more short (< 3 s) trophallactic contacts when pollen need was high, resulting in an increase of total number of trophallactic contacts. Thus, our results support the hypothesis that trophallactic experience is one of the various information pathways used by pollen foragers to assess their colony's pollen need. [source]

    Racial Differences in Division of Labor in Colonies of the Honey Bee (Apis mellifera)

    ETHOLOGY, Issue 2 2002
    Charles Brillet
    We measured the age at onset of foraging in colonies derived from three races of European honey bees, Apis mellifera mellifera, Apis mellifera caucasica and Apis mellifera ligustica, using a cross-fostering design that involved six unrelated colonies of each race. There was a significant effect of the race of the introduced bees on the age at onset of foraging: cohorts of A. m. ligustica bees showed the earliest onset, regardless of the race of the colony they were introduced to. There also was a significant effect of the race of the host colony: cohorts of bees introduced into mellifera colonies showed the earliest onset of foraging, regardless of the race of the bees introduced. Significant inter-trial differences also were detected, primarily because of a later onset of foraging in trials conducted during the autumn (September,October). These results demonstrate differences among European races of honey bees in one important component of colony division of labor. They also provide a starting point for analyses of the evolution of division of labor under different ecological conditions. [source]

    Helicobacter pylori mutagenesis by mariner in vitro transposition

    Betty P Guo
    Abstract We have developed a method for generating transposon insertion mutants using mariner in vitro mutagenesis. The gene of interest was PCR-amplified and cloned. A kanamycin-marked mariner transposon was randomly inserted into the purified plasmid in an in vitro transposition reaction. After repair and propagation in Escherichia coli, purified mutagenized plasmid was introduced into Helicobacter pylori by natural transformation. Transformants were selected by plating on kanamycin. Mutants were predominantly the result of double homologous recombination, and multiple mutants (with insertions in distinct positions) were often obtained. The site of insertion was determined by PCR or sequencing. We have made mutations in known or potential virulence genes, including ureA, hopZ, and vacA, using kanamycin- and kanamycin/lacZ -marked transposons. Colonies carrying a kanamycin/lacZ transposon appeared blue on medium containing the chromogenic agent X-gal, allowing discrimination of mutant and wild-type H. pylori in mixed competition experiments. [source]

    To the Islands , Photographs of Tropical Colonies in The Queenslander

    Hannah Perkins
    Australian readers knew a great deal about the Pacific Islands in the early 20th century. This understanding came from missionary fund-raising campaigns, visiting lantern-slide lecturers, postcards and illustrated books and encyclopaedia but most of all, after the mid-1890s, from heavily illustrated weekend newspapers. These were published in all major cities and offered a regular visual window on ,the islands', of which three were Australian colonies shortly after World War I. This paper argues that Australians were well-informed about the potential for settlement, and commercial and economic opportunities. It notes that illustrated newspapers were dominated by ethnographic images of the material culture and lifestyles of island peoples, but that images of wharves, plantations, port towns and colonial infrastructure were provided for those readers who thought the western Pacific should become an Australian or at least a British sphere of interest. Ultimately The Queenslander's editorial motivation was to alert Australian readers to the economic potential of plantations, trade, mining, travel and settling in the nearby tropics. [source]

    Structure and signaling in polyps of a colonial hydroid

    Neil W. Blackstone
    Abstract. After feeding, polyps of colonial hydroids contract regularly, dispersing food throughout the colony via the gastrovascular fluid. Such contractions may trigger signaling pathways that allow colonies to grow in an adaptive manner, i.e., to initiate development of more polyps in food-rich areas and to suppress polyp development in food-poor areas. In this context, we investigated the structure and potential signaling of the junction between polyps and stolons in colonies of the hydroid Podocoryna carnea. Using transmission electron microscopy, we found that the density of mitochondrion-rich epitheliomuscular cells was low in polyp and stolon tissues except at or near the polyp-stolon junction, where many of these mitochondrion-rich cells occur in ectodermal tissue. In vivo fluorescence microscopy suggests that these mitochondria are a principal source of the metabolic signals of the colony. Both native fluorescence of NAD(P)H and fluorescence from peroxides (visualized with H2DCFDA) co-localize to this region of the polyp. Rhodamine 123 fluorescence suggests that both these metabolic signals emanate from mitochondria. To test whether such metabolic signals may be involved in colony pattern formation, inbred lines of P. carnea were used. Colonies of a runner-like inbred line grow with widely spaced polyps and long stolonal connections, much like wild-type colonies in a food-poor environment. Colonies of a sheet-like inbred line grow with closely spaced polyps and short stolonal connections, similar to wild-type colonies in a food-rich environment. Polyp-stolon junctions in runner-like and sheet-like colonies were imaged for the fluorescence of H2DCFDA. Densitometric analysis of this signal indicates that the mitochondria in epitheliomuscular cells of runner-like polyps emit greater amounts of peroxides. Because peroxides and other reactive oxygen species are frequently intermediaries in metabolic signaling pathways, we suspect that such signaling may indeed occur at polyp-stolon junctions, affecting colony pattern formation in these inbred lines and possibly in hydroid colonies in general. [source]

    Colony growth responses of the Caribbean octocoral, Pseudopterogorgia elisabethae, to harvesting

    John Castanaro
    Abstract. Colonies of the branching Caribbean gorgonian Pseudopterogorgia elisabethae were subjected to partial mortality at 2 sites in the Bahamas to study how colony growth responds to disturbances such as harvesting, grazing, and storm damage. Colonies were clipped so that either 4 branches or 10 branches remained. Growth rates of branches were then monitored over 1 year and compared with nearby unclipped colonies. No significant differences were found between branch extension rates among the 3 treatments. Extension rates of newly formed branches were significantly greater in all treatments than among branches present at the start of the experiment. Per capita branching rates were greater on the more severely clipped colonies and were smallest on control colonies. The absolute number of branches that became mother branches did not differ among treatments. Colonies clipped so that 4 and 10 branches remained had the same average number of mother branches per colony, and there was no significant difference between treatments in the average number of new branches formed on the colonies. Per capita branching rates were significantly different among treatments only because the relative proportion of branches that became mother branches was higher in colonies with four branches than in treatments with more initial branches. Total growth (cumulative growth on all branches) was not significantly different between the 2 clipped treatments. Many of the control colonies suffered extensive damage, which may have obscured the comparison of clipped and unclipped treatments; however, within the range of these clipping treatments, differing levels of partial mortality did not lead to different recovery rates. The lack of treatment effects is particularly relevant to assessing the effects of harvest techniques on the recovery and productivity of harvested, naturally occurring, colonies. [source]

    Spatial differences in breeding success in the pied avocet Recurvirostra avosetta: effects of habitat on hatching success and chick survival

    Szabolcs Lengyel
    I studied the breeding biology of pied avocets Recurvirostra avosetta in natural habitats (alkaline lakes), and in semi-natural sites (dry fishpond, reconstructed wetlands) in Hungary to relate habitat selection patterns to spatial and temporal variation in breeding success. Colonies were initiated earlier in semi-natural sites than in natural habitats, and earlier on islands than on the mainland. Hatching success was higher on islands than on the mainland, in semi-natural sites than in natural habitats, in colonies of at least 15 pairs than in smaller colonies, and for nests initiated earlier than later within a colony. Fledging success was higher in the wet years (1999,2000) than in the dry year (1998), decreased strongly by season in both habitats and increased with average daily temperature in the first week post-hatch in 1999,2000. Most pairs hatching young in semi-natural sites attempted to lead their chicks to feeding areas in natural habitats, whereas no such movement occurred in the opposite direction. Chick mortality due to predation was high during brood movements and only 23% of the pairs moving their young produced fledglings, compared to 43% for pairs remaining in semi-natural sites and 68% for pairs hatching and rearing young in natural habitats (total n=192 broods). These results suggest that semi-natural sites were more suitable for nesting, whereas natural habitats were more suitable for chick-rearing. The opposing trends in habitat-related breeding success between nesting and chick-rearing suggest sub-optimal habitat selection by Pied Avocets due to an incorrect assessment of the potential for successful reproduction of semi-natural sites, which may thus function as ecological traps. [source]

    Sib-mating in the ant Plagiolepis pygmaea: adaptative inbreeding?

    Abstract Multiple functional queens in a colony (polygyny) and multiple mating by queens (polyandry) in social insects challenge kin selection, because they dilute inclusive fitness benefits from helping. Colonies of the ant Plagiolepis pygmaea brash contain several hundreds of multiply mated queens. Yet, within-colony relatedness remains unexpectedly high. This stems from low male dispersal, extensive mating among relatives and adoption of young queens in the natal colony. We investigated whether inbreeding results from workers expelling foreign males, and/or from preferential mating between related partners. Our data show that workers actively repel unrelated males entering their colony, and that queens preferentially mate with related males. These results are consistent with inclusive fitness being a driving force for inbreeding: by preventing outbreeding, workers reduce erosion of relatedness within colonies due to polygyny and polyandry. That virgin queens mate preferentially with related males could result from a long history of inbreeding, which is expected to reduce depression in species with regular sibmating. [source]

    Unclaimed Colonies: Anglo-Greek Identities Through the Prism of the Dilessi/Marathon Murders (1870)

    Rodanthi Tzanelli
    This paper examines the Anglo-Greek dialogue on Greek and British European identities following the Dilessi/Marathon Murders, a case of kidnapping and murder of three upper class Britons by Greek brigands, which became the European cause célèbre of the 1870s. It focuses on British and Greek narratives of brigandage and uses them to provide some insight into the ways both sides conceptualised modernity. The uses of the Greek, Irish and Scottish past and present in this dialogue formed a discourse in which history, imperialism and romanticism were woven altogether. This paper argues that these intertwined ideas and processes were complicit in the formation of modern British and Greek national identities. [source]

    Re-Thinking the ,Origins Debate': Race Formation and Political Formations in England's Chesapeake Colonies

    Chris Smaje
    The debate over the ,origins' of racism in colonial North America has been dominated by the view that racism was a consequence of the enslavement of African-origin labour, or alternatively that it was a prior , perhaps primordial , sentiment that shaped the process of enslavement. This paper offers an alternative reading of the evidence in suggesting that race formation can be understood in relation to the emergence of new forms of imagining political communities in early modern England, and Europe more generally. This argument can not only help refine understanding of race formation in early colonial America, but also sociological theories of race more generally, while helping avoid some of the theoretical problems entailed in attempting to trace the ,origins' of social phenomena. [source]

    First Report of Rhizoctonia solani AG-7 on Cotton in Egypt

    Kamel A. Abd-Elsalam
    Abstract Eighty-two isolates of Rhizoctonia solani were recorded from roots of naturally-infected seedlings of the Egyptian cotton (Gossypium barbadense L.). Anastomosis groups (AGs) of the isolates were determined by using 13 different AGs testers. Three (3.7%) of the isolates were identified as R. solani AG7, while the remaining isolates were belonging to the AG 2-1, AG4 and AG5. The identification of the three isolates was based on the frequency of the C2 reaction with the AG7 tester isolate. No fusion was observed between AG7 and isolates representing the other 13 AGs. Colonies of AG7 isolates grown on potato dextrose agar (PDA), malt yeast agar (MYA) and melt peptone agar (MPA) were brown to dark brown with aerial mycelium and sclerotia. The isolates had pitted sclerotial clusters and brownish exudates after 21 days of culturing on PDA, but without clear zonation. Pathogenicity test under greenhouse conditions revealed that AG7 caused the common symptoms of damping,off, which included seed rot, lesions on the hypocotyls and root rot. [source]

    A Simple Technique for Purifying Fungal Cultures Contaminated with Bacteria and Mites

    S. S. Ko
    A simple technique was developed for purifying fungal cultures contaminated with bacteria and mites. It was based on the observation that the growth of bacteria and movement of mites were confined to the upper surface of the agar. A culture contaminated with bacteria and mites was transferred to a piece of clean paper with the upper surface facing down. Small thin pieces (approximately 3 mm × 3 mm × 0.5 mm) of agar were removed from the exposed surface and transferred to a V-8 agar plate. Colonies that developed from these agar pieces were free from bacteria and mites. [source]

    Adult mortality rates in young colonies of a swarm-founding social wasp (Polybia occidentalis)

    JOURNAL OF ZOOLOGY, Issue 1 2003
    Andrew M. Bouwma
    The swarm founders are unusual among the social wasps in having socialized the dispersal stage of the life cycle. Colonies are initiated by groups of workers accompanied by smaller numbers of queens. Thus, swarm founders avoid the colony size bottleneck faced by the independent founders, whose colonies start with one or a few queens. Among the advantages of swarm founding is a reduction of the risk of colony failure due to attrition of the founding adults. Stochasticity in adult mortality is less likely to lead to outright extinction of a large founding group before new workers are produced (pre-emergence period). However, it is not known how important pre-emergence mortality is as a selective force on founding and dispersal behaviour in swarm founders, since colony-wide mortality rates have never been reported for a large-colony social wasp. Sixty-eight swarms of Polybia occidentalis were censused just before colony initiation and again 24 days later. Mortality over this period averaged 0.41±0.12 of the founding swarm population. Including mortality on the day of emigration and extrapolating to day 30, when the first adult offspring eclose, the original absconding swarm would be reduced by 0.52 of its initial size. Rates of loss during the first week, while the colonies engaged in nest construction, did not differ from rates over the full 24 days. Thus, colony founding in P. occidentalis is both costly and highly variable in terms of mortality of the founding adults. [source]

    Recrudescence of sexual activity in a colony of the Mashona mole-rat (Cryptomys darlingi): an apparent case of incest avoidance

    JOURNAL OF ZOOLOGY, Issue 2 2001
    M. Herbst
    Abstract Colonies of the Mashona mole-rat Cryptomys darlingi are founded from a single reproductive pair of animals that are genetically unrelated by descent. All non-reproductive animals are the progeny of the reproductive pair. Non-reproductive colony members do not seem to be suppressed from reproduction at the level of the pituitary. In colonies in which the reproductive female is removed or dies, there is strict incest avoidance and the colony remains reproductively quiescent. Reinstatement of sexual activity in a queenless colony may be brought about in the laboratory by the introduction of unfamiliar and unrelated adult males. In the queenless colony under study, there was a marked change in the dominance hierarchy with an increase in Landau's index of linearity from 0.61 to 1.0 on the introduction of two unrelated males. The two new males became the most dominant within the colony. All previously non-reproductive females exhibited heightened urinary oestradiol 17, and progesterone concentrations on the introduction of the males. However, it was only the older and most dominant non-reproductive female that became the new reproductive female and produced a litter of three pups 70 days after the initial introduction. [source]

    Pseudoplanktonic lifestyle of the Triassic crinoid Traumatocrinus from Southwest China

    LETHAIA, Issue 3 2006
    Wang Xiaofeng
    Colonies of Traumatocrinus (Echinodermata, Crinoidea) attached to driftwood from the lower Upper Triassic (Carnian) Xiaowa Formation of the Guanling area (Guizhou, Southwest China) document a pseudoplanktonic lifestyle for this specialized offshoot of the otherwise benthic Middle Triassic Encrinidae. After the end-Carnian decline of Traumatocrinus, its ecological niche was subsumed in Norian by genera derived from another benthic family (Holocrinidae) with convergent morphological modifications. After the Toarcian (Lower Jurassic), this niche disappeared, possibly due to the emergence of wood-boring bivalves. [source]

    Polyandry and fitness in the western harvester ant, Pogonomyrmex occidentalis

    MOLECULAR ECOLOGY, Issue 6 2004
    Diane C. Wiernasz
    Abstract Using four highly polymorphic microsatellite markers (12,28 alleles), we gentoyped workers from 63 colonies of Pogonomyrmex occidentalis. Colonies have a single, multiply mated queen, and an average number of 6.3 patrilines per colony. Colony growth was measured over an 8-year period in the study population. Intracolonial relatedness and colony growth are correlated negatively, indicating a substantial fitness benefit to multiple mating. [source]

    Possible role of the adhesin ace and collagen adherence in conveying resistance to disinfectants on Enterococcus faecalis

    G. Kayaoglu
    Introduction:, This study aimed to evaluate whether the presence of the ace gene and Ace-mediated binding to collagen confers on Enterococcus faecalis resistance against common endodontic disinfectants. Methods:, Isogenic strains of E. faecalis: OG1RF (wild-type) and TX5256 (ace insertion mutant of OG1RF) were grown in brain,heart infusion broth at 46°C overnight. Standardized bacterial suspensions were pretreated for 1 h either with acid-soluble collagen or acidified phosphate-buffered saline (ac-PBS). Bacteria were challenged with chlorhexidine digluconate (CHX), iodine potassium-iodide (IKI), sodium hypochlorite (NaOCl), and calcium hydroxide [Ca(OH)2]. Samples were removed at 1, 3, and 6 h, and cultured on Todd,Hewitt agar plates. Colonies were counted, the absolute values were log transformed, and the data were statistically analyzed using Fisher's least significant differences test and t -test. Results:, OG1RF was more resistant than TX5256 to IKI, NaOCl, and Ca(OH)2 (P < 0.05). Collagen-exposed OG1RF was more resistant than the ac-PBS-pretreated OG1RF against CHX at 3 h and against IKI at 1 h (P < 0.05); no significant difference was found against NaOCl. As expected, the ace mutant strain, TX5256, pretreated with collagen or ac-PBS did not differ significantly in viability when challenged with CHX, IKI, and NaOCl. An unexpected result was found for Ca(OH)2: collagen-pretreated OG1RF and TX5256 were both more susceptible than ac-PBS-pretreated OG1RF and TX5256, respectively (P < 0.05). Conclusion:, The presence of the ace gene confers resistance against IKI, NaOCl, and Ca(OH)2 on E. faecalis. Exposure to collagen makes the wild-type bacterium more resistant against CHX and IKI; however, exposure to collagen apparently decreases resistance to Ca(OH)2. [source]