bluuebunny/crossref_metadata_2025 huggingface dataset:
Sexual size dimorphism in steppe tortoises (Testudo horsfieldi): growth, maturity, and individual variation
Authors: Lagarde Frédéric , Bonnet Xavier , Henen Brian T , Corbin Johanna , Nagy Ken A , Naulleau Guy
Published: April 2011

Age and size at maturity are determined through complex interactions among size at birth, growth rate, maturation, and survival. We studied sexual size dimorphism and growth rate and maturation patterns in a long-lived organism, the steppe tortoise (Testudo horsfieldi), using the scute lamina number and width as age and growth measures. There was no sexual difference in the juvenile growth rate, but females matured later and hence were larger at maturity than males. We also observed considerable inter-individual variation in age and size at maturity. In both sexes, precocious animals grew faster during the juvenile phase but matured at a smaller body size than did tardy animals. Consequently, maturity did not seem size-dependent per se but rather was determined by growth rate. The strong variation between and within the sexes in age and size at maturity suggest that different growth trajectories and maturation schedules depend upon sex and individual responses to resource availability.
The shell glands in some calanoid copepods (Crustacea)
Authors: Barthélémy Roxane-Marie , Cuoc Corinne , Caubit Xavier , Brunet Michel
Published: April 2011

This study represents the first structural, ultrastructural, and biochemical investigation of the shell glands in calanoid copepods. These glands, located inside the points of the last prosomal segment, constitute voluminous syncytial secretory units, each of which extends into an excretory canalicule with a cellular or syncytial wall. The canalicules merge into two collector canals, or shell ducts, that rejoin the oviducts and then open into the egg-laying ducts. Each secretory unit synthesizes heterogeneous granules containing both light and predominantly dense material. Exocytosis of these mature secretory granules occurs in an apical excretory chamber. In freshwater species, the modifications observed during the secretory cycle emphasize a gradual discharge from the secretory units in the hours following laying. Cytochemical and biochemical studies of the secretions reveal the presence of N-acetylglucosamine, galactose, and N-acetylgalactosamine glycoconjugated proteins.
Pretty patterns but a simple strategy: predator-prey interactions between juvenile herring and Atlantic puffins observed with multibeam sonar
Authors: Axelsen Bjørn Erik , Anker-Nilssen Tycho , Fossum Petter , Kvamme Cecilie , Nøttestad Leif
Published: April 2011

Predatorprey interactions between Atlantic puffins (Fratercula arctica) and newly metamorphosed herring (Clupea harengus) were studied in the Lofoten-Røst area in northern Norway using a high-resolution multibeam sonar system. Attacks from diving puffins and predatory fish induced massive predator-response patterns at the school level, including bend, vacuole, hourglass, pseudopodium, herd, and split. All patterns have previously been observed, using the same sonar, in schools of adult herring attacked by groups of killer whales. Tight ball, the prevailing response pattern in adult fish under predation, was not observed, but a new pattern, intraschool density propagation, was found and interpreted as an analogue to tight-ball formations moving rapidly within the school. The observed patterns persisted much longer than in schools of adult herring attacked by killer whales, reflecting the different hunting strategies. Traditionally, the repertoire of predator responses observed in schooling fish has been interpreted as a range of co operative tactics to trick predators, but this has recently been challenged by authors who suggested that fish that behave the same way produce different patterns at group level simply by maintaining a minimum approach distance to predators and hiding behind conspecifics (the "selfish herd"), and that the particular combination of group size and number and behaviour of predators, rather than different individual tactics, determines the outcome at group level. Our findings support the latter hypothesis.
Factors determining "gaps" in the distribution of a small carnivore, the common genet (Genetta genetta), in central Spain
Authors: Virgós Emilio , Romero Teresa , Mangas Julián G
Published: April 2011

We studied the pattern of distribution of the common genet (Genetta genetta) in areas in mountains and plains of central Spain, in the middle of the range of the species. We evaluated the role of temperature, rainfall, and habitat features in determining the ecological limits of genet distribution. Genets were very scarce on plateaux and the upper parts of the mountains, but were widely distributed in lower mountain areas. Genets were present in areas with abundant shrub cover, high mean of the mean minimum temperature and high mean of mean winter temperatures. Survey routes at the same altitude (<1000 m) in the mountains (genets abundant) and on the plateaux (genets very scarce) also differed in some of these variables, with low values on the plateaux for shrub cover, mean of the mean minimum temperatures, mean of the mean winter temperatures, and annual rainfall. Genets originated in Africa, therefore they are probably ill-adapted (morphologically and physiologically) for the cold conditions predominating in most of central Spain. Their preference for shrubby habitats may be linked to a greater availability of food and low risk of predation. Intermediate levels of rainfall may be correlated with higher temperatures, the key factor hypothesized to affect the distribution of this species. The distribution of the common genet fits a multimodal model, with peaks (presence) and valleys (absence) in the middle of its range, indicating that location in a particular part of the range is not a prior indicator of habitat suitability for the species.
Characteristics of dispersal in wolverines
Authors: Vangen Knut Morten , Persson Jens , Landa Arild , Andersen Roy , Segerström Peter
Published: April 2011

We studied patterns of dispersal and sizes of home ranges of juvenile wolverines (Gulo gulo). Mean dispersal age was 13 months for both male (n = 11) and female (n = 9) wolverines. Females displayed more variation in dispersal age (726 months) than males (718 months). Of the animals used in the dispersal analyses, all males and 69% of females dispersed. All sedentary females (n = 4) occupied their mother's territory when she died or shifted territory, and no females dispersed from a territory vacated by their mother. Competition for resources seemed to determine the female dispersal pattern, while competition for mates seemed to explain the male dispersal pattern. Dispersal distances averaged 51 km for males and 60 km for females. However, this is likely to be an underestimation. Eight cases of exploratory movements were observed, and on average, these immediately preceded dispersal movements. The size of juvenile home ranges of males (85 km2) and females (81 km2) corresponded to the home-range area of denning females during the summer period. Wolverines have the capacity to recolonize gaps in the present distribution of the species in Scandinavia. Other factors, therefore, most likely explain the large proportion of vacant wolverine habitats.
Space-use strategies of female polar bears in a dynamic sea ice habitat
Authors: Mauritzen Mette , Derocher Andrew E , Wiig Øystein
Published: April 2011

In environments with high spatiotemporal variability in resources, animals may exhibit nomadic movements for resource tracking as opposed to long-term area fidelity. Polar bears (Ursus maritimus) inhabit the dynamic sea ice, preying on seals, and demonstrate considerable intraspecific variation in space use. We studied patterns of fidelity and annual range size for 74 adult female polar bears captured in the Norwegian Arctic that were tracked for up to 5 years using satellite telemetry data. We used the autocorrelation structure of movements and distance between observations at a 1-year interval as measures of fidelity. The female polar bears had a circannual migration pattern. Annual range size varied with reproductive state and geographic location of the range. Females entering maternity dens had smaller annual ranges than females not entering dens. Nearshore females had smaller annual ranges than pelagic females, demonstrating different space-use strategies. Repeatability of movement patterns indicated strategy specialization. We suggest that the different space-use strategies result from variation in habitat and prey selection and in sea-ice dynamics. Factors affecting population and predatorprey dynamics may interact differently with the different space-use strategies and yield strategy-dependent outcomes, therefore a knowledge of movement strategies may be important for understanding polar bear population dynamics.
Developmental stages of Haemogregarina delagei in the leech Oxytonostoma typica
Authors: Siddall Mark E , Desser Sherwin S
Published: April 2011

Haemogregarine infections in little skates, Raja erinacea, were assessed for a period of approximately 1 year. Prevalence of Haemogregarina delagei in little skates varied seasonally between 77 and 91%. Prevalence of leeches (Oxytonostoma typica) varied between 9 and 18%. One leech was removed from a little skate (from Passamaquoddy Bay, New Brunswick) heavily infected with H. delagei. Imprints made from the leech's digestive tissue contained haemogregarine oocysts that produced 1632 sporozoites, and meronts with 4 merozoites. The latter were also found in imprints made from salivary tissues.
Changes in oceanographic conditions off northern British Columbia (19831999) and the reproduction of a marine bird, the Ancient Murrelet (Synthliboramphus antiquus)
Authors: Gaston Anthony J , Smith Joanna L
Published: April 2011

We examined variation in breeding-biology parameters for Ancient Murrelets (Synthliboramphus antiquus), marine birds breeding in central Hecate Strait, British Columbia, over the period 19831999. Interannual changes were compared with physical oceanographic data (sea-surface temperatures (SSTs) and Southern Oscillation (SO) indices) for surrounding waters. No secular change in oceanographic data for Hecate Strait was detectable for the period considered, which embraced two major (19821983, 19971998) and three minor El Niño  Southern Oscillation (ENSO) events. SSTs were strongly related to the SO index for the area considered. Breeding-biology data were not available for the 19821983 ENSO. The 19971998 ENSO had a strong effect on breeding success, reducing the number of chicks per pair from >1.4 to below 1; most of this effect was caused by desertions before incubation began. We found a positive correlation between May SST and the slope of the regression of chick mass at colony departure on a particular date for a given year. This effect may have resulted from the failure of young or otherwise less competent birds to rear young in years of high SSTs. Both the median date of colony departure and chick mass at departure declined over the period of the study, although neither effect was related to changes in the oceanographic variables considered in this study. These trends may relate to longer term changes in oceanographic conditions in the North Pacific Ocean. If they continue, the recent trend towards lower chick masses at colony departure may have adverse effects on recruitment and eventually on Ancient Murrelet populations.
Population estimation with sparse data: the role of estimators versus indices revisited
Authors: McKelvey Kevin S , Pearson Dean E
Published: April 2011

The use of indices to evaluate small-mammal populations has been heavily criticized, yet a review of small-mammal studies published from 1996 through 2000 indicated that indices are still the primary methods employed for measuring populations. The literature review also found that 98% of the samples collected in these studies were too small for reliable selection among population-estimation models. Researchers therefore generally have a choice between using a default estimator or an index, a choice for which the consequences have not been critically evaluated. We examined the use of a closed-population enumeration index, the number of unique individuals captured (Mt+1), and 3 population estimators for estimating simulated small populations (N = 50) under variable effects of time, trap-induced behavior, individual heterogeneity in trapping probabilities, and detection probabilities. Simulation results indicated that the estimators produced population estimates with low bias and high precision when the estimator reflected the underlying sources of variation in capture probability. However, when the underlying sources of variation deviated from model assumptions, bias was often high and results were inconsistent. In our simulations, Mt+1 generally exhibited lower variance and less sensitivity to the sources of variation in capture probabilities than the estimators.
Food habits and space use of gray foxes in relation to sympatric coyotes and bobcats
Authors: Neale Jennifer CC , Sacks Benjamin N
Published: April 2011

To investigate interspecific relationships between gray foxes (Urocyon cinereoargenteus) and sympatric coyotes (Canis latrans) and bobcats (Lynx rufus), we quantified occurrence of food items in carnivore scats and used relative abundances of scats on transects to assess space use. Dietary-overlap indices between the two canid species were high during summer and fall ([Formula: see text] = 0.89) when fruits were prevalent in scats of both species, and were lower during winter and spring ([Formula: see text] = 0.70) when fruits were less available. Foxes differed most from coyotes in their relatively less frequent ungulate consumption. Foxbobcat dietary-overlap indices were relatively low in summer and fall ([Formula: see text] = 0.37) and greater in winter and spring ([Formula: see text] = 0.74). Foxes differed most from bobcats in their more frequent consumption of fruits and less frequent consumption of lagomorphs. Abundance of fox scats was positively correlated with abundance of coyote scats during both winterspring (r = 0.52, p = 0.02) and summerfall (r = 0.75, p < 0.001) and with abundance of bobcat scats during winterspring (r = 0.59, p < 0.01) and summerfall (r = 0.22, p > 0.10). Thus, despite similarities in diet, we found no evidence that gray foxes avoided these larger predators in space.
The direct and indirect effects of temperature on a predatorprey relationship
Authors: Anderson Michael T , Kiesecker Joseph M , Chivers Douglas P , Blaustein Andrew R
Published: April 2011

Abiotic factors may directly influence community structure by influencing biotic interactions. In aquatic systems, where gape-limited predators are common, abiotic factors that influence organisms' growth rates potentially mediate predatorprey interactions indirectly through effects on prey size. We tested the hypothesis that temperature influences interactions between aquatic size-limited insect predators (Notonecta kirbyi) and their larval anuran prey (Hyla regilla) beyond its indirect effect on prey size. Notonecta kirbyi and H. regilla were raised and tested in predatorprey trials at one of three experimentally maintained temperatures, 9.9, 20.7, or 25.7°C. Temperature strongly influenced anuran growth and predator success; mean tadpole mass over time was positively related to temperature, while the number of prey caught was negatively related. At higher temperatures tadpoles attained greater mass more quickly, allowing them to avoid capture by notonectids. However, the probability of capture is a function of both mass and temperature; temperature was a significant explanatory variable in a logistic regression equation predicting prey capture. For a given prey mass, tadpoles raised in warmer water experienced a higher probability of capture by notonectids. Thus, rather than being static, prey size refugia are influenced directly by abiotic factors, in this case temperature. This suggests that temperature exerts differential effects on notonectid and larval anurans, leading to differences in the probability of prey capture for a given prey mass. Therefore, temperature can influence predatorprey interactions via indirect effects on prey size and direct effects on prey.
Comparing movement patterns of satellite-tagged male and female polar bears
Authors: Amstrup S C , Durner G M , McDonald T L , Mulcahy D M , Garner G W
Published: April 2011

Satellite radiotelemetry has provided great insights into the movements and behaviors of polar bears (Ursus maritimus). The diameter of the neck of adult male polar bears exceeds that of their head, however, and radio collars slip off. This has limited collection of movement information to that from radio-collared females. To overcome this difficulty and gather information about their movements, we surgically implanted satellite radio transmitters into 7 male polar bears during 1996 and 1997. We compared movements of implanted males with those of 104 adult females radio-collared between 1985 and 1995. Transmitters were implanted under the skin on the midline of the top of the neck and were equipped with percutaneous antennae. Implanted transmitters operated for up to 161 days providing 3217 satellite relocations. While transmitting, radios implanted in males provided a larger proportion of the highest quality category of position fixes than was obtained from radio-collared females. However, all implanted radios ceased transmitting before reaching their projected life-span. The abrupt termination of transmission from implanted radios suggested mechanical rather than electronic failure. Mean rates of short-term movement for males (1.18 km/h) were lower than for solitary females, females with cubs, and females with yearlings (1.70, 1.84, and 1.95 km/h, respectively). Net geographic movements from the beginning to the end of each month were comparable for males (mean = 135 km) and females (mean = 114, 152, and 168 km). Mean azimuths of these net movements also appeared to be similar. Monthly activity-area sizes for males (mean = 8541 km2) were comparable to those for females (mean = 3698, 9397, and 10 585 km2) during the time period of comparison. In contrast to the other movement measures, males traveled longer mean distances (387 km) each month than did females (217, 289, and 302 km). Movements of males, it appears, were more directed than those of females, but males confined their travels to similar-sized areas.
Decline and regional extirpation of freshwater mussels (Unionidae) in a small river system invaded by Dreissena polymorpha: the Rideau River, 19932000
Authors: Martel André L , Pathy Diane A , Madill Jacqueline B , Renaud Claude B , Dean Stuart L , Kerr Steven J
Published: April 2011

Data pertaining to the ecological impact of the exotic zebra mussel, Dreissena polymorpha, on benthic fauna in small river systems are scarce. We conducted a long-term study to assess the impacts of the D. polymorpha invasion in a small river system (100 km) in eastern Ontario during an 8-year period (19932000). A 30-km downstream section of the Rideau River was studied before and during rapid population growth of D. polymorpha in the area. During 19931995, D. polymorpha abundance on hard substrates increased by four to six orders of magnitude and remained high thereafter. A comparable temporal pattern of D. polymorpha abundance was observed on shells of live freshwater mussels (Unionidae). During peak fouling (19951997), mass ratios (mass of attached D. polymorpha / mass of live unionid host) ranged from 0.37 to 1.81. SCUBA-diving surveys (50-m transects) were conducted to examine the impact of D. polymorpha on native unionids in impounded river habitats. In 19931994, three unionid taxa were commonly found in 10-m2 quadrats sampled along transects: Elliptio complanata, Pyganodon grandis, and Lampsilis radiata. Overall, the mean density of unionids declined 5- to 8-fold from 1993 to 1997, coinciding with a rapid increase in D. polymorpha densities on unionids. By 1997, i.e., 4 years after fouling began, P. grandis and L. radiata had been extirpated from those sites, with only E. complanata remaining. By 2000, i.e., 7 years after fouling began, all three unionid taxa had been essentially extirpated from the 30-km section of the river, with only one live individual (E. complanata) collected during 10 extensive diving surveys (the total estimated area of riverbed surveyed was 4000 m2). This study indicates that heavy fouling by D. polymorpha causes the extirpation of unionids in small impounded river systems ([Formula: see text]100 km).
Natural and experimental nematode infections in red deer (Cervus elaphus elaphus) and the potential for antemortem serodiagnosis of the tissue worm Elaphostrongylus cervi
Authors: Duffy M S , Waldrup K A , Mackintosh C G , Pearse A J , Taylor M J , Labes R E , Burt M DB
Published: April 2011

Red deer (Cervus elaphus elaphus) were exposed to a variety of nematodes, either naturally on pasture (n = 12) or experimentally under controlled conditions (n = 30). Experimental exposures included a combination of one or more of Elaphostrongylus cervi, Dictyocaulus sp., and Muellerius capillaris. The prepatent period of E. cervi infections was 92133 days post exposure (dpe) in 12 deer each given 2042 infective larvae (L3) and maintained under controlled conditions. Adult E. cervi were recovered from all 12 animals at necropsy. The prepatent period of Dictyocaulus sp. was 2337 dpe in 10 deer each given 100 L3 and maintained under controlled conditions. Adult Dictyocaulus sp. were recovered from seven animals at necropsy. No animal exposed to 4254 M. capillaris L3 developed patent infections, nor were adult worms recovered at necropsy. There was no evidence of neurologic signs in any deer at any time during the experiment. An enzyme-linked immunosorbent assay (ELISA) using somatic protein extracts of adult E. cervi or those from the closely related nematode Parelaphostrongylus tenuis was evaluated. Although the ELISA was sensitive, it lacked specificity with heterologous infections. However, the close phylogenetic relationship of E. cervi to P. tenuis, and our ELISA results, suggest that molecules from P. tenuis may represent a viable alternative source for use in the future development of a reliable antemortem serodiagnostic assay for E. cervi.
Movement patterns of male common voles (Microtus arvalis) in a network of Y junctions: role of distant visual cues and scent marks
Authors: Dobly Alexandre
Published: April 2011

Common voles (Microtus arvalis) use networks of runways around their burrows, which are dug in meadows. Their orientation among such networks could be based on rigid "egocentred" routes (possibly through the use of olfactory "trails") or on more general, "allocentred" spatial representations (with distant visual cues). In this 5-day study, male voles should reach food in the centre of a maze of three-way (Y) junctions offering similar local views but surrounded by distant visual cues. I tested whether the animals navigated using olfactory trails, implying one main direct foraging route, or allocentered representations, allowing flexibility among equivalent routes. Males quickly marked their environment, preferentially at the periphery, where they moved the most. However, during most direct trips between the nest and the food, they used one of the central shortest routes, which included the least scent-marked zones. Moreover, the voles preferred different shortest routes to go to the food and return from it, showing a bias in favour of the side where the distant goal (food or nest) was situated. This suggests that male common voles base their choices on the general direction of their goal rather than on trails. Finally, there was no major difference in initial exploration between a clean and a scent-marked maze.
ASPECTS QUANTITATIFS DES BESOINS EN MINÉRAUX DE TRIBOLIUM CONFUSUM DUVAL: II. POURCENTAGE OPTIMUM DES CATIONS Mg, Ca, Na et K
Authors: Huot L. , Bernard R. , Lemonde A.
Published: April 2011

The quantitative requirements of the Tribolium confusum larvae for magnesium, calcium, sodium, and potassium are reported. Magnesium and potassium are definitely essential for larval growth. Without these elements, the larvae do not survive long. Calcium appears essential for imaginal metamorphosis. In its absence, rapid dehydration of the pupae occurs and emergence of the adult is practically suppressed. The importance of sodium could not be demonstrated because the minute quantities already present in the basal diet appear sufficient to meet the requirements of this insect. The requirements of both sexes for these cations are of the same order of magnitude. Additions of these cations in excess of the optimum values are well tolerated.
NUCLEAR ACTIVITY OF BLOOD CELLS
Authors: Engelbert Vibeke E.
Published: April 2011

This paper presents the continuation of studies on blood cell behaviors published earlier by Engelbert.It was then shown that "nuclear bodies" named "basic nuclear units" passed through several stages of a nuclear life history which was believed to hold the key to blood cell cytogenesis. Blood cell polymorphism or pleomorphism is believed to be products of the many staged nuclear life history. The nuclear life history can be experimentally altered, for example by foreign proteins. The basic nuclear units are believed to be reproductive organelles.Additional evidence of nuclear behaviors fitting into the nuclear life history is presented. Formation and release of vesicles by myeloblast nuclei was demonstrated earlier. Evidence is presented here to show that the production and release of these intranuclear vesicles is not a sign of degeneration, but a process by which new cells can be produced through reassociation of released nuclear materials. Some released vesicles become red blood cells. Extreme variations in shape of myeloblast nuclei are not signs of degeneration, but are characteristic nuclear behaviors associated with nuclear activity.The release of new small nuclei, intranuclear vesicles, and various granules are nuclear activities leading to formation of new cells.
STUDIES ON STRONGYLOIDES OF PRIMATES: II. FACTORS DETERMINING THE "DIRECT" AND THE "INDIRECT" MODE OF LIFE
Authors: Premvati
Published: April 2011

Under optimum conditions Strongyloides fülleborni has an indirect life cycle but under adverse conditions, only infective larvae and males are developed. Adverse factors such as pH and consistency of media, absence of food, and unsuitable temperatures appear to act directly on the first-stage rhabditiform larvae developed from the eggs of parasitic females. The potential female larva alone becomes an infective larva, the potential male being unaffected. There is a single free-living generation and all eggs laid by free-living females develop directly into infective larvae. The infective larvae developed directly or indirectly can develop only into parthenogenetic females.
CORYNOSOMA MAGDALENI SP. NOV. (ACANTHOCEPHALA), A PARASITE OF THE GRAY SEAL IN EASTERN CANADA
Authors: Montreuil Paul L.
Published: April 2011

Corynosoma magdaleni sp. nov. (Acanthocephala) is described from the gray seal, Halichoerus grypus (Fabricius), and the Atlantic harbor seal, Phoca vitulina concolor (DeKay), the latter as an infrequent accidental host in Eastern Canada. Juveniles were found in halibut, Hippoglossus hippoglossus (Linn.) and shorthorn sculpin, Myoxocephalus scorpius (Linn.) in the Magdalen Islands region of the Gulf of St. Lawrence.
RELATIONSHIP OF RESPIRATION RATE TO TEMPERATURE IN A SUPERCOOLED INSECT
Authors: Salt R. W.
Published: April 2011

The rate of oxygen consumption of mature larvae of Anagasta kühniella (Zell.) exhibits a logarithmic relationship to temperature over a range extending from the limit of supercooling to the beginning of heat injury. This information supplements that of Scholander et al. (4), who demonstrated the same relationship in frozen Chironomus larvae, the rate being lower than in supercooled forms and hence not continuous with the above-zero portion of the curve. Together, these two simple relationships invalidate Kozhantschikov's theory of cold-hardiness based on a thermostable respiration below 0 °C. in cold-hardy insects and no respiration in frozen non-cold-hardy insects.
ANATOMY AND HISTOLOGY OF THE FULL-GROWN LARVA OF CTENICERA AERIPENNIS DESTRUCTOR (BROWN) (COLEOPTERA: ELATERIDAE)
Authors: Eidt D. C.
Published: April 2011

The internal anatomy and histology of the full-grown larva of Clenicera aeripennis destructor, the prairie grain wireworm, is described and illustrated in part. Included are the digestive, circulatory, respiratory, and nervous systems; the fat body, oenocytes, corpora allata; and the muscles of the head, digestive tract, and dorsal vessel.
SOME NOTES ON A COLLECTION OF POLYCHAETA FROM THE NORTHEAST PACIFIC SOUTH OF LATITUDE 32° N.
Authors: Berkeley E. , Berkeley C.
Published: April 2011

Twenty-nine species of Polychaeta collected on, or near, the west coast of Lower California and of Mexico are recorded. Seventeen of them are pelagic. Of these, 10 are heteronereid phases of various Nereidae, in two of which cases (Perinereis monterea and Nereis oligohalina) neither of the heteronereid phases has been described previously. One species recorded (Maupasia caeca) is new to the northeast Pacific.
THE MEASUREMENT OF SPRUCE BUDWORM POPULATIONS AND MORTALITY DURING THE FIRST AND SECOND LARVAL INSTARS
Authors: Miller C. A.
Published: April 2011

Two methods of assessing II-instar budworm populations in hibernacula are presented and a general comparison shows that the collection of foliage samples in the spring and sampling the whole branch as a unit is an acceptable technique. This population assessment permits the partitioning of the total population reduction from the I- to the III-instar larval stage into I-instar dispersal loss in the fall and II-instar dispersal loss in the spring. Estimates of these losses are presented and other mortality factors in operation during this age-interval are discussed.
THE METAZOAN PARASITES OF THE HETEROSOMATA OF THE GULF OF ST. LAWRENCE: IV. CESTODA
Authors: Ronald Keith
Published: April 2011

Diplocotyle olrikii, Clestobothrium crassiceps, Bothriocephalus scorpii, and B. claviceps; Scolex pleuronectis, Phyllobothrium sp. (larva), and a tetraphillidean plerocercoid (Cestoda) were identified in a study of 560 specimens of Heterosomata (Hippoglossoides platessoides, Hippoglossus hippoglossus, Limanda ferruginea, Liopsetta putnami, Pseudopleuronectes americanus, and Scophthalmus aquosus) from the Gulf of St. Lawrence area. The distribution of the hosts is indicated.
ON PRENATAL INFECTION AND THE MIGRATION OF TOXOCARA CANIS WERNER, 1782 IN DOGS
Authors: Webster Gloria A.
Published: April 2011

A definite age–sex–migration complex has been determined during studies on the migratory behavior of Toxocara canis Werner, 1782 in dogs. It has also been established that intrauterine infection occurs as a result of the reactivation of larvae in the somatic tissues of the bitch during gestation.
THE NAUPLIAR STAGES OF BALANUS NUBILIS DARWIN
Authors: Barnes H. , Barnes Margaret
Published: April 2011

The details of morphology of the six naupliar stages of Balanus nubilis are described. The nauplii are particularly characterized by their large size and in the later stages by a distinctly pentagonal outline. The general pattern of development conforms to that previously found for balanid nauplii. Tables are given of sizes and setation formulae.
The effect of various combinations of immature queen and worker bees on the ovary development of worker honeybees in colonies with and without queens
Authors: Jay S. C.
Published: April 2011

The ovaries of worker honeybees of known age were examined at intervals after the bees had been introduced to colonies with queens, or without queens. These colonies contained immature queen and worker bees in various combinations.Inhibition of ovary development in the test worker bees appeared to depend on the presence of worker caste larvae or pupae and not on the presence of larval, pupal, or adult queens.
Bees and blueberries
Authors: Helms Carl W.
Published: April 2011

Bumblebees feed on blueberries through the open end of the corolla tube, while honeybees reach the nectaries through slits in the side of the flower.
The in vitro growth and development of the early larval stages of the codworm, Terranova decipiens
Authors: McClelland G. , Ronald K.
Published: April 2011

The second-stage larva of the codworm, Terranova decipiens, has been cultivated in Eagle's basal medium (BME) and 20% foetal calf serum over a period of 4 months. Thus far, exsheathment, growth to 10 × 0.20 mm, and the early development of the intestinal caecum have been completed.
Grit ingestion by nestling Tree Swallows and House Wrens
Authors: Mayoh Keith R. , Zach Reto
Published: April 2011

We examined the stomach contents of 200 Tree Swallow (Tachycineta bicolor) and 187 House Wren (Troglodytes aedon) nestlings for grit. Grit, composed mainly of small stones, sand, and mollusk shells or fragments, was found in 35% of the swallow and 31% of the wren stomachs. Grit ingestion started about 3 d following hatching in wrens and about 5 d after hatching in swallows. After reaching a peak, it declined in both species towards fledging. The mean number of grit particles was 10.2 in swallows and was significantly lower than that of 22.3 in wrens. The mean mass of grit particles was 17.2 mg in swallows and was significantly higher than that of 6.2 mg in wrens. The number and mass of grit particles were significantly correlated with age in swallows; only the latter correlation was significant in wrens. Analysis of a few adult stomachs suggested that grit ingestion was similar to that of nestlings.
The effects of forest disturbance on land gastropod communities in northern New England
Authors: Strayer David , Pletscher Daniel H. , Hamburg Steven P. , Nodvin Stephen C.
Published: April 2011

We studied the gastropod communities of 16 forested sites in northern New England that had been disturbed by clear-cutting, agricultural cropping, or forest fires. There was no clear relationship between the density, species richness, or composition of the gastropod community and the time elapsed since disturbance. This result contrasts with previous studies, which reported strong correlations between the age of forested stands and the structure of gastropod communities. We suggest that gastropod communities in our study sites recovered rapidly following disturbance because of the small area of the disturbed sites, which facilitated recolonization from surrounding areas, and because of the rapid recovery of the function of the vegetation following forest disturbance in northern New England.
Comparison of maturation of female Clethrionomys glareolus from cyclic and noncyclic populations
Authors: Bondrup-Nielsen Søren , Ims Rolf Anker
Published: April 2011

We examined the effect of mothers with and without new litters on maturation and growth of their daughters in laboratory colonies derived from cyclic and noncyclic populations of Clethrionomys glareolus. Mature individuals from cyclic populations are heavier than those from noncyclic populations, however, this difference was lost in our colonies. The presence of a mother had a significant effect in delaying vaginal perforation in cyclic females but not in noncyclic females. If a mother in the cyclic colony had a new litter and was lactating she appeared to be more effective in delaying vaginal perforation of her daughter than if she did not have a litter. The results are discussed in light of previous knowledge of factors affecting maturation in males and theory on population density dynamics.
Cholinergic inhibition of muscle contraction in Hymenolepis diminuta (Cestoda)
Authors: Thompson C. S. , Sangster N. C. , Mettrick D. F.
Published: April 2011

Spontaneous contractions of the longitudinal musculature from the strobilae of the tapeworm Hymenolepis diminuta were measured by means of a force transducer. The addition of cholinergic agonists and antagonists to the bathing medium did not affect intact worms but strips of worm tissue were sensitive to these drugs. Acetylcholine and cholinergic agonists inhibited muscle contraction while cholinergic antagonists stimulated contraction. Both nicotine and muscarine were effective in suppressing muscle contraction and the receptor probably has mixed nicotinic and muscaric properties. Biochemical assays revealed the presence of choline and acetylcholine, and activities of choline acetyltransferase and acetylcholinesterase in worm tissues.
On the mating system of polar bears
Authors: Ramsay Malcolm A. , Stirling Ian
Published: April 2011

Polar bears are intimately associated with arctic sea ice and their distribution is approximated by its winter extent. They are the only terrestrial mammals, other than humans, to have adapted so completely to sea ice, a quite different habitat, spatially and temporally, from that occupied by other terrestrial mammals. We propose that the dynamics of sea ice and the associated variability in access to food have played a major role in the evolution of the social structure and mating system of polar bears. Adult females and males move to areas of the sea ice where the greatest success in hunting is realized. Such regions are unpredictable in location, however, both seasonally and annually. Because female distributions are unpredictable, adult males are unable to defend stable territories that will encompass the home ranges of one or more females and may instead distribute themselves among different sea-ice habitats at the same relative densities as solitary adult females. Females keep nursing cubs with them for more than 1 year; hence the mean interbirth interval is 2 or more years. This results in a functionally skewed sex ratio, with fewer females available to breed in any one year than males, and in intrasexual competition among males for access to breeding females. Consequently, established dominance hierarchies among males are unstable, and wounding, scarring, and breakage of canine teeth are common; these are evidence of direct physical confrontations during the breeding season. Large body size is advantageous in these fights and this has resulted in one of the highest degrees of sexual dimorphism among terrestrial mammals. Because of the funtionally skewed sex ratio and the shifting distribution of both females and males, however, even the largest male probably cannot be certain of locating a larger than average number of receptive females in any one breeding season.
Morphologie bucco-linguale d'une guilde de canards barboteurs
Authors: Tremblay Serge , Couture Richard
Published: April 2011

Interspecific variations of bucco-lingual characteristics were measured in a guild of dabbling ducks and the influence of these characteristics on the use of food resources was studied. Morphological characters of the bill and tongue were measured in eight species of dabbling ducks of the genus Anas. Our results show that there are interspecific differences in the bucco-lingual characteristics of all species studied except for the Black Duck (Anas rubripes) and the Mallard (Anas platyrhynchos). There was a significant correlation between the density of bill lamellae and the weight of the species (r = −0.935, P < 0.01). In six species, the density of the lamellae was correlated with the volumetric index of the bill (r = −0.960, P < 0.01). These results indicate that in species with large bills the density of the lamellae is low, whereas in species with small bills, the number of lamellae is high. The volumetric index of the bill was significantly related to the average weight of each duck species (r = −0.905, P < 0.01). Dabbling ducks that filter benthic material can thus be classified on a scale based on lamellar density and bill volume. The differences in bucco-lingual morphlogical characters seem to reflect a mode of resource partitioning that diminishes competition.[Journal translation]
Les Alvinellidae, une famille nouvelle d'annélides polychètes inféodées aux sources hydrothermales sous-marines: systématique, biologie et écologie
Authors: Desbruyères Daniel , Laubier Lucien
Published: April 2011

Examination of all the specimens collected from deep hydrothermal vents in the eastern Pacific allowed us to describe two new species and one new subspecies belonging to the genus Paralvinella Desbruyères and Laubier, 1982: P. pandorae sp.n., P. palmiformis sp. n., and P. pandorae irlandei ssp. n. Alvinella pompejana is split into two species, A. pompejana and A. caudata sp.n., based on to morphological and biochemical data. The six species and subspecies of Alvinellinae (Polychaeta: Ampharetidae) are well separated from all other terebellomorph species by the absence of differentiation between thorax and abdomen. We propose here the erection of a new family, Alvinellidae, which seems to be primitive within the order Terebellida. All known alvinellids are strictly associated with deep hydrothermal vent phenomena.
Genetic variation and population differentiation in species of Simocephalus (Cladocera, Daphniidae)
Authors: Hann B. J. , Hebert P. D. N.
Published: April 2011

Microgeographic analysis of enzyme genetic variation in populations in the littoral zone cladoceran Simocephalus in southwestern Ontario has disclosed very low levels of intrapopulation variability. The mean percentage of polymorphic loci per population was 10.5%, and individual heterozygosity averaged less than 5% over all populations. Population structure typifies that of randomly mating, outbred sexual species. Most populations were polyclonal, with a few common widespread clones and several rarer ones, often found in only one pond. There were no significant temporal patterns in genotypic frequencies, but spatial differentiation of populations suggested that both selection and founder effects have played roles in the evolutionary divergence of these cyclic parthenogens. Despite extremely low intrapopulation and moderate intraspecific variation, there was extensive differentiation between species. As a consequence of virtually complete allelic substitution at several loci and great similarity or identity of alleles at others, diagnostic loci were detected in three of the four species. Of the four distinct clusters of populations, differentiated at the species level, three represented species previously recognized in North America (S. cf. vetulus, S. cf. serrulatus, S. cf. exspinosus), and the fourth group was identified as S. cf. congener, related to a taxon occurring in Europe, but not reported from North America. The great amount of divergence between populations of S. cf. exspinosus suggests that a complex of at least two sibling species exists within this taxon.
The importance of pattern in visual attraction of Tabanus nigrovittatus Macquart (Diptera: Tabanidae)
Authors: Allan S. A. , Stoffolano Jr. J. G.
Published: April 2011

Host-seeking female Tabanus nigrovittatus Macquart primarily use visual cues to locate hosts and host mimics. The importance of various attributes of patterns to this behavior was examined in the field using black and white two-dimensional panels. Panels with a square, circle, or star of equal size were equally attractive as were panels with stars with increasingly complex edges. In a series of panels with black circles of increasing size, attraction increased as the size of the circles increased. High contour density was not important in series of panels with increasing size and decreasing number of patterns (squares or circles), and large patterns with simple edges were most attractive. Both light objects against a dark background and dark objects against a light background were highly attractive. The response of flies to objects with stripes indicated that stripes decreased attraction, possibly as a result of shape disruption. These results indicate that solid, compact, large objects with high contrast against the background were the most attractive to host-seeking flies and that fine pattern detail was not important.
Changes in pedal intramuscular pressure corresponding to behavior and locomotion in the marine gastropods Busycon contrarium and Haliotis kamtschatkana
Authors: Voltzow Janice
Published: April 2011

Pedal intramuscular pressure recordings from the marine gastropods Busycon contrarium and Haliotis kamtschatkana were made using a wick catheter. Patterns of pressure fluctuations corresponded to a range of behavioral modes and locomotor speeds and reflected the morphological differences between the two regions of the foot, the columellar muscle and tarsos. Recordings from stationary specimens of both species showed sinusoidal pressure fluctuations corresponding to the heart beat. Pressure fluctuations in the foot of crawling Busycon were irregular and corresponded to the muscle action of its indistinct locomotor wave. Those from crawling Haliotis were characterized by regularly spaced, larger pressure peaks ascribable to the localized increase in pressure caused by the passing locomotor wave. The frequency and amplitude of these peaks increased with the speed at which Haliotis crawled. Additional large pressure pulses of over 3.4 kPa were recorded when snails twisted or lifted their shells, or brought their shells closer to the substratum, movements that are caused by the contraction of the columellar muscle.
Development of larval snailfishes (Pisces: Cyclopteridae: Liparidinae) from the western North Atlantic
Authors: Able Kenneth W. , Fahay Michael P. , Markle Douglas F.
Published: April 2011

Development of 9 of the 14 snailfishes in the western North Atlantic is described. Identification of larvae of Careproctus reinhardi, six species of Liparis (L. atlanticus, L. coheni, L. fabricii, L. gibbus, L. inquilinus, L. tunicatus), and two species of Paraliparis (P. calidus, P. copei) is based on body proportions, pigmentation, meristic characters, and early development of adult characters. Liparis fabricii is distinct from all other Liparis in having the darkest pigmentation at all sizes, largest sizes at all development stages, and unique body proportions. Liparis atlanticus and L. inquilinus are dissimilar to all other Liparis in the relatively smaller sizes at comparable stages of development and the presence of a notched dorsal fin. They differ from each other in pigmentation pattern and eye diameter/disk length ratio. Liparis coheni and L. gibbus are relatively smaller at all stages of development than L. fabricii but larger than L. atlanticus and L. inquilinus, and lack a notch in the dorsal fin. Liparis gibbus differs from L. coheni in pigmentation pattern and in having a larger eye diameter/disk length ratio. Pronounced geographic variation in pigmentation occurs between L. gibbus from the Canadian Arctic and those from the Gulf of St. Lawrence. The two Paraliparis and C. reinhardi possess adult fin ray counts and pigmentation at hatching and are easily distinguishable. Development in the latter species, which hatch as demersal juveniles, is distinctly different from that in Liparis, which hatch early in development (preflexion) and are pelagic until caudal formation is nearly complete (late flexion). For each species we include larval diagnostic characters, descriptive development (morphometric, pigmentation, meristic), and geographic and seasonal distribution of larvae.
The social organisation of Halictus ligatus (Hymenoptera; Halictidae) in southern Ontario
Authors: Packer Laurence
Published: April 2011

The social organisation of Halictus ligatus was studied at Victoria, southern Ontario. At this locality, the one worker brood has a protracted period of emergence; this results in small colony populations throughout the summer activity phase. Workers average 12.7% smaller than their queens, 60% of them have some ovarian development, and 42% of them mate. More males are produced towards the very end of the first brood than earlier in the spring provisioning phase. These late first brood males probably survive to mate with reproductive brood females. In orphaned nests, one worker dominates the others to become a replacement queen. Most replacement queens are mated and orphaned colonies produce reproductives of both sexes. Data from this population are compared with those of other studies of this, and other, halictine species.