bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the internal morphology of adults of a population of lampreys that contains a nonparasitic life-history type, Lampetra richardsoni, and a potentially parasitic form, L. richardsoni var. marifuga
Authors: Youson John H. , Beamish Richard J.
Published: August 2008

Histological techniques were used to study adults of a single population of the brook lamprey, Lampetra richardsoni, in Morrison Creek, Vancouver Island, British Columbia, to establish whether there are any differences between the internal morphology of a "silver" variety (L. r. var. marifuga) and that of the nonparasitic variety (L. richardsoni). The results of the study support the view of two life-history types in this creek. When L. richardsoni is sexually mature and has an atrophied intestine and sparse haemopoietic tissue, most L. r. var. marifuga possess a maturing (not totally mature) gonad, a highly developed alimentary canal containing ingested food, and extensive haemopoietic tissue. Although the gills, thyroid gland, and the definitive kidneys are similar in both forms, incomplete regression of the larval kidney and the absence of a cranial pancreas in all L. r. var. marifuga imply that a slow sexual maturation is accompanied by a slow, and perhaps incomplete, metamorphosis. The incomplete metamorphosis is particularly exemplified in female L. r. var. marifuga and may account for the abnormal sex ratio of this variety. The retardation of sexual maturation in male L. r. var. marifuga permits the retention of a functional digestive system and, hence, provides an opportunity for feeding. The significance of these observations to present views on the evolution of lampreys is discussed.
The mandibles of some adult ground beetles: structure, function, and the evolution of herbivory (Coleoptera: Carabidae)
Authors: Acorn John H. , Ball George E.
Published: August 2008

The structure of carabid and other adephagan mandibles can provide information about the mechanics of feeding in these beetles and about the major features of carabid and adephagan evolution. Homologies among mandibular features are proposed, based on a transformation series for adult mandibles from plesiotypic cupedid-like structure to derived conditions characteristic of herbivorous carabids in the subtribe Harpalina. Terms for mandibular parts are revised so that all ridges and teeth are referred to as such. The following terms are introduced: superior and inferior terebral ridges, superior and inferior retinacular ridges, supraterebral ridges, anterior and posterior occlusal grooves, and basal face. Masticatory function is elucidated for the mandibles of adult Euryderus grossus (Say) in which the mandibles shear food matter in both a horizontal and a vertical plane, as well as compacting food into a bolus that is forced posteriorly into the buccal cavity. Many of the features of E. grossus mandibles are characteristic of other herbivorous carabids, but not all such taxa show such derived mandibular structure.
Prevalence and abundance of helminth parasites in an intensively fished population of brook trout (Salvelinus fontinalis) at a small subarctic lake
Authors: Albert E. , Curtis M. A.
Published: August 2008

Brook trout from a 5-ha lake near Schefferville, Quebec, were intensively sampled by small-mesh gill nets during 2 successive years to study patterns of helminth parasite occurrence in relation to changes in the age and size class structure of the fish population. Nearly 1800 brook trout were removed from the lake, of which all were measured and weighed, 568 were aged by otolith readings, and 361 were examined for parasites. The digeneans Crepidostomum farionis, Phyllodistomum umblae, and Diplostomum sp. and the cestode Eubothrium salvelini were present in more than 50% of the necropsied fish, and the prevalence and (or) abundance of all species except C. farionis increased from the first to the second year of the study. The fish catch in the first year was dominated by the 3+ year class and older fish, whereas by the second year 1+ and 2+ fish were proportionately more abundant, and the importance of older cohorts declined. This change in brook trout population structure, resulting from gill net selectivity, appears to have had the effect of improving per capita food availability for members of the residual stock. After the initial year of intensive fishing, the fish that remained fed more upon both benthic and planktonic invertebrates and their acquisition of parasites was intensified.
Experimental transmission of Gyrodactylus salaris Malmberg, 1957 (Platyhelminthes, Monogenea) from the Atlantic salmon (Salmo salar) to the European eel (Anguilla anguilla)
Authors: Bakke T. A. , Jansen P. A. , Hansen L. P.
Published: August 2008

Laboratory experiments were designed as follows in an attempt to evaluate the potential importance of eels in dispersal of Gyrodactylus salaris: exposure of uninfected eels to infected salmon; exposure of infected eels to uninfected salmon; exposure of uninfected eels to infected eels; indirect infection of uninfected eels; parasite transmission preference, using "two-choice" host tests; and parasite survival on eels following their isolation. Gyrodactylus salaris was found to be transmissible from salmon to eels, and vice versa, both at 4 and 13 °C. Eel to eel transfer of G. salaris was also demonstrated, as was infection of fish from the bottom of the tank. Transmission of G. salaris to eels also occurred in the "two-choice" host tests. Transmission rate was positively correlated with water temperature and transmission was more frequent from dead than living infected salmon. The maximum duration of infection on eels was 8 days. The transfer of infection to eels is thought to parallel events in nature and forms part of the dispersal mechanism of G. salaris.
Age-specific reproduction in feral horses
Authors: Garrott Robert A. , Eagle Thomas C. , Plotka Edward D.
Published: August 2008

Two age-specific reproduction schedules were constructed for feral horses (Equus caballus) on the basis of lactation status of 14 788 females captured during herd reduction programs and pregnancy rates of 667 horses determined by serum progesterone assays. The probability of detecting lactation progressively decreased for females captured further from the foaling season, indicating that these data resulted in substantial underestimates of true foaling rates. A third reproductive schedule was, therefore, constructed on the basis of a subsample of 1144 horses captured immediately after the foaling season in June. Characteristics common across all three data sets were first reproduction at age 2, an increase in the proportion of females foaling through age 6, highest foaling rates from 6 to 15 years, and a gradual decrease in foaling rates of females >15 years. Variability in the proportion of reproductively active females in each age-class was detected among populations and among years within a population; however, the general trend was high reproductive rates, with 80–90% of the prime-age females foaling. The reproduction model suggested by L. L. Eberhardt, provided a close mathematical approximation of the observed age-specific changes in foaling rates, providing a useful tool for the construction of reproduction schedules required for age-structured population models.
Growth and seasonal weight changes as they relate to spring and autumn set points in mule deer
Authors: Renecker Lyle A. , Samuel W. M.
Published: August 2008

Growth rate and potential, 25 hand-reared mule deer (Odocoileus hemionus hemionus) were examined. When possible, body weights of all animals were recorded weekly. Female deer matured faster than males, but males attained a larger body size. Regressions of winter weight loss of both sexes on peak autumn weight were highly correlated. Similarly, spring and summer compensatory gain in females could be predicted from the minimum spring weight. Annual cycles of intake and weight gain may have adaptations that improve reproductive success and winter survival.
Seasonal dynamics, benthic habitat use, and drift of zooplankton in a small stream in southern Oklahoma, U.S.A.
Authors: Richardson William B.
Published: August 2008

Seasonal dynamics of zooplankton were examined in Rock Creek, a second-order stream in south central Oklahoma, U.S.A. Periodic samples were taken of zooplankton and environmental variables in a pool and in drift above and below the pool. A field manipulation was conducted to investigate the role of benthic water movement and substratum angle of orientation as factors affecting microcrustacean densities on substratum in pools. Variation in densities of cyclopoid copepods and rotifers were best predicted by the product of pool retention time and water temperature (cyclopoids: r = 0.91, P = 0.0001; rotifers: r = 0.90, P = 0.0001). Algal biomass was the best predictor of Cladocera densities (r = 0.54, P = 0.05). Pool retention time and water temperature had little direct effect on Cladocera densities. Microcrustacea and rotifers were imported into the pool during flooding and exported during low flow periods in the summer. Postflood pool densities decreased rapidly after flooding. Microcrustacea were most abundant on experimental vertical substrates in nonflowing areas (PF × A = 0.0001). These substrates had the greatest epilithic biomass and chlorophyll a content. All microcrustacean and rotifers commonly occurring in the pool were associated with benthic and (or) littoral habitats. This habitat association is probably the primary mechanism for resisting downstream movement.
Influence of detectability and ability to escape on natural selection of conspicuous autotomous defenses
Authors: Cooper Jr. William E. , Vitt Laurie J.
Published: August 2008

Antipredatory adaptations in which a predator's attack is diverted to body parts that may be sacrificed or are less vulnerable sometimes depend upon the conspicuousness of the body part attacked. The predator's attention is drawn to the emphasized part, which serves as a decoy. Such defenses appear paradoxical in that they increase the probability of detection. However, they simultaneously increase the probability of postdetectional escape enough to decrease the overall probability of being killed. Based on probabilities of detection and of escape following detection, a simple model predicts the conditions in which autotomy and related defenses are favored. For a conspicuous decoy, equilibrium values of the increases in probabilities of detection and of escape following detection are given. Data on the conditional probability of escape after detection are discussed for the scincid lizards Eumeces fasciatus and E. laticeps, which have brightly colored autotomous tails. Versions of the model that split the predator–prey encounter into several successive stages are outlined briefly and illustrated by the data for the two lizard species. Strategies for measuring the probabilities and testing the model's predictions are considered.
Life cycles of 12 species of winter stoneflies from Quebec (Plecoptera; Capniidae and Taeniopterygidae)
Authors: Harper P. P. , Lauzon M. , Harper F.
Published: August 2008

The life cycles of 12 species of winter stoneflies belonging to the families Capniidae and Taeniopterygidae were studied in six river systems (seven sampling sites) in southern Quebec. Eight of the cycles were previously undescribed. All species were univoltine. Adults emerged as soon as the ice broke on the streams in late winter, except for Paracapnia angulata, Taenionema atlanticum, and Strophopteryx fasciata, which emerged about 3 weeks later. The simplest cycle occurred in Paracapnia opis, and P. angulata: egg development was direct and nymphal growth proceeded steadily from May to January. All other species showed evidence of a nymphal diapause interrupting development between June and September. In Allocapnia pygmaea, A. recta, C. vernalis, Taeniopteryx maura, T. parvula, and Oemopteryx glacialis, growth was completed by January, but A. minima, A. maria, Taenionema atlanticum, and Strophopteryx fasciata continued to develop through the winter and reached maturity just before emergence. Allocapnia recta, the first species to emerge, was also the first to mature, but the population showed much variability and the last nymphs to emerge were probably the only ones to survive and reproduce under Quebec climatic conditions.
Intraspecific killing of preweaned young in the Columbian ground squirrel, Spermophilus columbianus
Authors: Hare James F.
Published: August 2008

The abandonment of Columbian ground squirrel (Spermophilus columbianus) neonates by their dams when dams and litters were released from field enclosures resulted in the availability of newborn pups aboveground to male and female conspecifics. Four incidents of infanticide were observed and, without exception, perpetrators of infanticide were female, although male conspecifics had equal access to pups. Contrary to an earlier conjecture that male Columbian ground squirrels are the more likely perpetrators of infanticide, this finding is consistent with the majority of incidents documented for this species.
Do brook charr (Salvelinus fontinalis) from insular Newfoundland have different parasites than their mainland counterparts?
Authors: Marcogliese David J. , Cone David K.
Published: August 2008

Based on the published literature, comparison of the metazoan parasite faunas of brook char (Salvelinus fontinalis) from freshwater localities in northeastern North America reveals that hosts in insular Newfoundland have fewer parasite species recorded from them. Of 45 parasite species or taxa, only 20 are common to the island and the mainland. Twenty-three parasite species have been reported from the mainland but not from the island, with most of the taxa being types common to non-salmonid fishes. Two species, the copepod Ergasilus luciopercarum and the digenean Tetracotyle, have been reported from charr on the island but not from the northeastern mainland. It is suggested that the primary reason for the difference in the structure of the assemblages is the lack of contact brook charr in Newfoundland have with percid, cyprinid, centrarchid, esocid, and catostomid fishes and their parasites.
Pigmentation, otolith rings, and upstream migration of juvenile American eels (Anguilla rostrata) in a coastal Rhode Island stream
Authors: Haro Alexander J. , Krueger William H.
Published: August 2008

American eels of <250 mm total length were collected in late summer and fall from three stations on the coastal Annaquatucket River. All eels possessed the yellow–green pigmentation characteristic of the yellow phase. Transition of partially pigmented elvers to fully pigmented yellow eels occurred during the summer months following the spring entry into fresh water and was accompanied by significant growth. Mean total length and mean number of annulus-like otolith rings increased significantly with distance upstream, suggesting that elvers migrate a limited distance in the 1st year, but continue on for at least several years thereafter as yellow eels. Upstream progress of eels in this system may be impeded by low winter temperatures, high stream gradient, dams, and impoundments.
Competitive ability influences seaward migration age in Atlantic salmon
Authors: Metcalfe Neil B.
Published: August 2008

Juvenile Atlantic salmon (Salmo salar L.) reach a life-history decision in late summer as to whether they will migrate to sea the following spring or remain in fresh water for at least a further year. Here I show that the feeding efficiency of those fish that subsequently defer migration is significantly impaired by the presence of a size-matched competitor, whereas that of fish adopting the strategy of early migration is unaffected by a competitor's presence. This suggests that competitive ability influences the decision as to when to migrate, through its effect on food intake and growth rates, later migrating fish being the poorer competitors.
The influence of oviposition resources on the dispersion and behaviour of calopterygid damselflies
Authors: Meek Susan B. , Herman Thomas B.
Published: August 2008

We manipulated the size of oviposition patches to test two hypotheses: (i) in Calopteryx species males position themselves at patches where they have the greatest probability of finding females, and (ii) females are more strongly attracted to patches with the most oviposition resources. More females were attracted to large patches in all three species studied. In Calopteryx amata and Calopteryx maculata single males maintained territories at small patches and several males concurrently occupied and patrolled large patches. Calopteryx maculata males divided the large patches into small, individual territories, whereas C. amata males at large patches were unable to maintain exclusive areas. There were single territorial Calopteryx aequabilis males at both large and small patches. Time budgets of individual males were affected by the size of the oviposition patch most strongly in C. amata, where at large patches males engaged in aggression, patrolling, and courtship more frequently and for longer than at small patches. Calopteryx maculata males courted more frequently at large patches, but patrolling and male–male aggression were unaffected. Time budgets of C. aequabilis were virtually unaffected by the size of the oviposition patch. The frequency of mating by individual males did not differ between patch sizes for any of the three species. Dispersion and behaviour of damselflies of Calopteryx species are modified by the size and availability of oviposition resources.
Hematological and serum chemical characteristics of the Iberian lynx (Lynx pardina) in southwestern Spain
Authors: Beltrán J. F. , Delibes M. , Recio F. , Aza C.
Published: August 2008

Hematological and serum chemical values were determined for 16 wild Iberian lynxes, Lynx pardina (5 adult males, 4 adult females, 4 juvenile males, and 3 juvenile females) captured with box traps and coil-spring traps. The results include reference values, analysis of sex and age differences, and data on the influence of capture method on blood values. Males had higher red blood cell counts (p = 0.03) and packed cell volumes (p = 0.06) than females, which presented higher mean corpuscular hemoglobin levels (p = 0.08) and mean corpuscular hemoglobin concentrations (p = 0.07) than males. Juveniles had higher serum levels of alkaline phosphatase (p = 0.01), urea (p = 0.02), and cholesterol (p = 0.02) and lower levels of creatinine (p = 0.07) than adults. Four hematological variables (mean platelet volume, platelet size distribution, white blood cell count, and mean corpuscular volume) and two serum variables (concentrations of amylase and calcium) were influenced by capture method. The use of standard procedures to assess base-line blood values in wild carnivores is encouraged.
Influence of concurrent exposure to crude oil and infection with Trypanosoma murmanensis (Protozoa: Mastigophora) on mortality in winter flounder, Pseudopleuronectes americanus
Authors: Khan R. A.
Published: August 2008

A study was conducted to determine the influence of concurrent exposure to crude oil and a hemoprotozoan parasite, Trypanosoma murmanensis, on mortality in winter flounder, Pseudopleuronectes americanus. Both juvenile and adult flounder were infected and exposed to sediment contaminated with various concentrations (~100, 300, 600, 1000, and 2200 μg/g) of oil for 8 weeks at 0–1 °C in flow-through seawater aquaria with corresponding uncontaminated infected and uninfected groups. Mortality occurred earlier and was greater in juvenile fish exposed to crude oil than in adults. However, a larger percentage of oil-treated, infected adult flounder died after exposure at the highest concentrations. At the highest concentrations, selected organ somatic indices and blood values in surviving flounder were affected more in the infected, oil-treated fish than in corresponding controls. The prolonged period of patency of T. murmanensis in the oil-treated groups might be associated with immunosuppression.
Energy flux in a natural population of the land snail Eobania vermiculata (Müller) (Gastropoda: Pulmonata: Stylommatophora) in Greece
Authors: Lazaridou-Dimitriadou Maria , Kattoulas Marios E.
Published: August 2008

Survivorship, production, mortality rate, consumption rate, assimilation, and growth and ecological efficiencies were studied in a natural population of the land snail Eobania vermiculata in Greece. Eobania vermiculata may take 5 years or more to reach maximum size (33 mm). Mortality rate and life expectancy decreased with age. Net reproductive rate was 3.4 and per capita rate of increase was 1.0. Energy flux in E. vermiculata was studied using Urtica dioica and Lactuca sativa as food. The highest daily consumption and assimilation rates (weight specific) were observed in newly hatched animals and the lowest in adults. Assimilation efficiency, mean monthly production, and gross growth and ecological or net growth efficiencies fluctuated with the season and the physiology of the snails. Snails fed U. dioica showed higher assimilation, gross growth, and net growth efficiencies than those fed L. sativa. Energy flow through the E. vermiculata population was 78.9 cal∙m−2∙year−1 (1 cal = 4.1868 J), mean assimilation efficiency was 52% if the snails were fed U. dioica only, and the ingestion rate was 19.5%. When E. vermiculata was fed U. dioica during its lifetime, 4.26% of the total assimilated energy was used for egg production, 10.2% for growth, and 87.8% for metabolic energy. Annual secondary production gave a mean adult density of 4.1 individuals/m2, a mean annual standing crop (biomass) of 6.8 g∙m−2, and an annual production of 13.9 ± 1.8 g∙m−2 or 2859.5 mg C∙m−2. The annual turnover ratio, or productivity rate constant, was 2.0.
Resilience, robustness, and plasticity in a terrestrial slug, with particular reference to food quality
Authors: Rollo C. David , Shibata Diane M.
Published: August 2008

The terrestrial slug Deroceras laeve is abundant in diverse habitats spanning an enormous geographic range. This paper explores the hypothesis that much of this success may be attributed to phenotypic flexibility. Breeding experiments demonstrated that food quality had an enormous impact on growth and maturation rates, maturation sizes, reproduction, and longevity. Maturation rates and sizes covaried along a plastic development trajectory in response to dietary constraints on growth rate. The strategy for a particular dietary regime agreed well with known optimal control models. Published models developed for particular genotypes conformed to single cross sections along the plastic trajectory. Adaptive plasticity was augmented by resilient compensatory responses to food shortages, and robustness with respect to locomotor abilities, an omnivorous diet, and resistance to extreme temperatures. This combination of plasticity, resilience, and robustness could offset the low rate of sexual reproduction and associated low genetic variance documented in this species.
Geographic patterns of genetic differentiation among sexual populations of Daphnia pulex
Authors: Innes David J.
Published: August 2008

Previous surveys have shown that most populations of Daphnia pulex in the Great Lakes watershed reproduce by obligate parthenogenesis. Cyclically parthenogenetic populations, in which there is sexual reproduction, are confined to only a few isolated areas. The present study assessed genetic variation within and among 11 cyclically parthenogenetic populations. The results for six polymorphic enzyme loci showed that variation within the populations conformed to that expected for populations with frequent sexual reproduction. Seven of the populations sampled in 1988 were previously sampled in either 1985 or 1986. Allele frequencies determined in 1988 were very similar for the same loci sampled in previous years, and there was no evidence for the invasion of these populations by obligate parthenogens during this period. There was no significant difference in the average heterozygosity among the 11 populations. Although significant heterogeneity in allele frequencies was detected among the 11 populations for all six loci (average FST = 0.18), the pattern of population differentiation was only very weakly related to geographic distance. An analysis of gene diversity showed that the level of population differentiation for cyclically parthenogenetic D. pulex is much lower than has been observed for most other cladoceran species.
Fine structure and biology of Cryothecomonas gen. nov. (Protista incertae sedis) from the ice biota
Authors: Thomsen Helge A. , Buck Kurt R. , Bolt Patricia A. , Garrison David L.
Published: August 2008

The morphology and ultrastructure of four species of Cryothecomonas gen.nov. (Protista incertae sedis) in material from the Weddell Sea, Antarctica, and the Isefjord, Denmark, are described. These heterotrophic flagellates, which were initially observed in association with sea ice, display a unique combination of morphological characteristics. At present it is impossible to assign the new genus to an existing higher taxonomic level of protistan flagellates. Cryothecomonas species are furnished with a close-fitting multilayered theca. The two naked anterior flagella emerge through narrow thecal funnels. A transitional helix is part of the flagellar transition zone. A conspicuous cytostome is located in a posterior (lateral) position. Food uptake is mediated through the extension of cytostomal pseudopodia. The nucleus is anteriorly located and contains a conspicuous nucleolus and distinct areas of chromatin. Mitochondrial cristae are tubular. Cryothecomonas species feed on cells in the size range 2–4.5 μm (e.g., algal flagellates). Data are presented on the abundance of Cryothecomonas armigera sp.nov. in Antarctic waters.
Développement postembryonnaire du squelette et de la musculature de la tête de Clarias gariepinus (Pisces, Siluriformes) depuis l'éclosion jusqu'à 6,8 mm
Authors: Surlemont Chantal , Vandewalle Pierre
Published: August 2008

Upon hatching, the 4.2-mm fry of Clarias gariepinus has no skeleton (except for the notochord) or cephalic muscles. At 4.7 mm, the first elements of the chondrocranium have appeared, the few muscles that are present still have no definite insertion and there is no movement. At 6.8 mm, the chondrocranium is partially divided, the first elements of the osteocranium are present and most of the muscles are of the general type encountered in Teleosts and all have their proximal and distal insertions. Movements are then generally synchronyzed and can ensure ventilation of the gill arches. Exogeneous food intake is still not observed, although bone and muscle structures and movements could allow it and the vitellus is completely resorbed.[Translated by the Journal]
Instantaneous heart rates and other techniques introducing errors in the calculation of heart rate
Authors: Chabot Denis , Bayer Max , Roos André de
Published: August 2008

Data on heart rate can be analyzed in terms of beats per unit of time (heart rate) or its reciprocal, time per beat (interbeat interval). We show that counting beats (including fractions), averaging interbeat intervals, and measuring the time for a fixed number of beats are correct techniques to measure heart activity within observation periods. QRS counts are less precise, but not systematically biased. Conversely, averaging instantaneous heart rates always overestimates true heart rate. Arithmetic means across trials of equal duration are correct only when heart activity for each trial is expressed as mean heart rate. For observation periods with equal numbers of beats, heart activity for each trial must be expressed as mean interbeat interval. A literature survey showed that biased techniques were frequently used to calculate heart rate, and that about half of the studies did not provide sufficient information on the methods used.
Factors influencing dispersion of larval black flies (Diptera: Simuliidae): effects of the presence of an invertebrate predator
Authors: Ciborowski Jan J. H. , Craig Douglas A.
Published: August 2008

Laboratory experiments were conducted to study aggregative responses of larvae of Simulium vittatum Zetterstedt on a ceramic tile to activity of a predatory perlid stonefly, Claassenia sabulosa (Banks). Nearest-neighbor analysis indicated that larvae became aggregated regardless of whether a predator was present. There was no significant difference in either number of larvae remaining on the tile or degree of black fly aggregation between trials that lacked a predator and those in which a stonefly could travel over the tile. Direct contact between predator and prey caused single simuliid larvae to release from the substrate, but daytime black fly behaviour was otherwise unaffected by stonefly activity.
Potential use of helminth parasites in stock identification of flying squid, Ommastrephes bartrami, in North Pacific waters
Authors: Bower S. M. , Margolis L.
Published: August 2008

A survey of helminth parasites in 68 flying squid (Ommastrephes bartrami) from off the west coast of North America (between latitudes 41°03′ and 48°23′ N and longitudes 129°49′ and 133°08′ W) revealed the presence of numerous juvenile nematodes and cestodes. Larval Hysterothylacium sp. and metacestodes of Phyllobothrium sp. were common (prevalence: 100 and 94.1%, respectively; mean intensity: 54.6 ± 28.1 and 6.4 ± 4.5, respectively). In addition, nine flying squid had a total of 11 Anisakis simplex larvae, and one metacestode of Tentacularia sp. (probably T. coryphaenae) was found in the sample bag that held one flying squid. The only adult helminths recovered were seven specimens of Rhadinorhynchus sp. (Acanthocephala) from three squid. The parasite fauna of these squid was sufficiently different from that previously reported for O. bartrami from the northwestern Pacific Ocean to suggest that parasites may prove useful as a tool to determine if intermixing of squid stocks from their feeding grounds in the eastern and western North Pacific Ocean occurs on the spawning grounds.
Characterization of Hymenolepis diminuta (Cestoidea) strains, using enzyme isoelectric focusing
Authors: Dixon Brent R. , Arai Hisao P.
Published: August 2008

This study evaluates the use of enzyme isoelectric focusing on thin-layer agarose gels in the differentiation of six geographical isolates of the rat tapeworm Hymenolepis diminuta. Differences in the enzyme profiles among these strains were apparent in two of five enzymes examined. A Japanese strain differed from all others in its more anodally positioned malic enzyme bands. This enzyme profile may be attributed to its more recent isolation from the wild type or to the unique origin of this strain. Two qualitatively different phosphoglucomutase banding patterns were apparent among the H. diminuta strains. This polymorphic nature of phosphoglucomutase has similarly been observed in a number of earlier studies. A number of problems are associated with the traditional morphological means of identifying cestodes, particularly at the intraspecific level. The enzyme pattern differences observed among the strains in this study indicate that enzyme isoelectric focusing may be a useful alternative.
Patterns of seabird and marine mammal carcass deposition along the central California coast, 1980–1986
Authors: Bodkin James L. , Jameson Ronald J.
Published: August 2008

At monthly intervals from February 1980 through December 1986, a 14.5-km section of central California coastline was systematically surveyed for beach-cast carcasses of marine birds and mammals. Five hundred and fifty-four bird carcasses and 194 marine mammal carcasses were found. Common murres, western grebes, and Brandt's cormorants composed 45% of the bird total. California sea lions, sea otters, and harbor seals composed 90% of the mammal total. Several factors appeared to affect patterns of carcass deposition. The El Niño – Southern Oscillation (ENSO) of 1982–1983 was the dominant influence in terms of interannual variation in carcass deposition. During this ENSO, 56% of the seabirds and 48% of the marine mammals washed ashore. Patterns of intra-annual variation were species specific and were related to animal migration patterns, reproduction, and seasonal changes in weather. Nearshore currents and winds influenced the general area of carcass deposition, while beach substrate type and local patterns of sand deposition influenced the location of carcass deposition on a smaller spatial scale. Weekly surveys along a 1.1-km section of coastline indicated that 62% of bird carcasses and 41% of mammal carcasses remained on the beach less than 9 days. Cause of death was determined for only 8% of the carcasses. Oiling was the most common indication of cause of death in birds (6%). Neonates composed 8% of all mammal carcasses.
Development of the notochord in the Japanese medaka, Oryzias latipes (Teleostei; Cyprinodontidae), with special reference to desmosomal connections and functional integration with adjacent tissues
Authors: Ekanayake Sunetra , Hall Brian K.
Published: August 2008

We describe development of the notochord from stage 28 (appearance of fin folds) to stage 35 (5 days after hatching). Beginning immediately after hatching (stage 32), the notochord, vertebral bone, and axial muscles develop as a structural unit. Integration of this unit is effected by (i) the appearance and maturation of desmosomes with cytoplasmic plaques and tonofilaments, (ii) the deposition of vertebral bone at stage 32, and (iii) integration of the periosteum with the connective tissue capsule of the axial muscles. Desmosomes connect notochordal cells with one another and with cells of the notochordal epithelium. Extracellular matrix integrates bone with inner notochordal epithelium, periosteal cells with one another, and periosteum with the muscle connective tissue capsules. Therefore, development of desmosomes and deposition of extracellular matrices, beginning at stage 28, provide the cellular basis for the structural integration of notochord, bone, and muscle. Onset of structural integration immediately precedes the first vigorous movement that occurs at stage 29. This developmental analysis has therefore identified the cellular basis of the structural and functional integration of the axial locomotory tissues. Such an approach provides a means of understanding the developmental basis of functional morphology.
Genetic variability in natural populations of the gray wolf, Canis lupus
Authors: Kennedy Phyllis K. , Kennedy Michael L. , Clarkson Peter L. , Liepins Ilme S.
Published: August 2008

The genetic variability of gray wolves (Canis lupus) from northwestern Canada was assessed through starch-gel electrophoresis. Of 27 protein systems examined, 25, representing 37 presumptive loci, were consistently scorable; 7 proteins (5 were consistently scorable) exhibited polymorphism. The level of heterozygosity (3.0%) was medial relative to values reported for natural populations of Carnivora and high relative to values reported for natural populations of canids. An overall pattern of few deviations from Hardy–Weinberg expectations and some spatial heterogeneity was observed. Wolves associated with different caribou herds exhibited a low level of differentiation (FST = 0.029). The pattern of variability supports the view of a large panmictic population resulting from extensive movements of individuals and packs and from natural and human impacts on pack structure and formation.
Five species of Gyrodactylus Nordmann, 1832 (Monogenea) from freshwater fishes of Peru
Authors: An Liguo , Jara Cesar A. , Cone David K.
Published: August 2008

Five species of Gyrodactylus Nordmann, 1832 (Monogenea) are described from freshwater fishes of the Chicama and Moche rivers of Peru. The parasites represent the first known species of the genus from South America. Four species are new: G. lebiasinus n.sp., G. bimaculatus, n.sp., and G. slendrus n.sp. from Lebiasina bimaculata (Characidae) and G. pimelodellus n.sp. from Pimelodella yuncensis (Pimelodidae). Gyrodactylus turnbulli Harris, 1986 is reported from wild Poecilia reticulata (Poeciliidae). The material includes members tentatively assigned to the G. arcuatus species group, the G. eucaliae group, and the G. rarus group.
An ultrastructural study of the activation of the endocrine dorsal bodies in the snail Helix aspersa by mating
Authors: Saleuddin A. S. M. , Griffond Bernadette , Ashton Mary-Lou
Published: August 2008

The ultrastructural organization of the dorsal bodies of Helix aspersa was studied using serial sections. The dorsal body cells, which were found in groups of two to six in the connective tissue surrounding the brain, contacted each other and formed a network. They were innervated by two types of axons. Type I axons conformed with those described in earlier studies as inhibitory and originating from the cerebral green cells. Type II axons contained secretory granules that were morphologically distinct from and smaller than type I granules. Between the dorsal body cells and both axon types, localized modifications of the membrane were evident. Virgin snails, which grew faster (wet weight) than mated snails, did not lay viable eggs. A comparative morphometric analysis of the dorsal bodies of virgin and mated snails showed that in the latter there was an increase in the numbers of mitochondria, secretory granules, and Golgi bodies, with a concomitant decrease in the numbers of lipid droplets. However, no difference was found in the numbers of profiles of exocytotic release of secretory granules with the use of tannic acid methods. Mating, obligatory for oviposition of viable eggs, appeared to cause ultrastructural changes consistent with increased synthesis and release of the dorsal body hormone essential for vitellogenesis, ovulation, and, consequently, egg laying.
On the origin of the mesoderm in the Mexican axolotl, Ambystoma mexicanum
Authors: Whiteley Mary , Armstrong John B.
Published: August 2008

The origin of the mesoderm in the Mexican axolotl, Ambystoma mexicanum, has been the subject of discussion in the literature for some time. Løvtrup proposed that the mesoderm originated from cells that were displaced from the blastocoel roof to the ring-shaped groove surrounding the arching endodermal primordium. Smith and Malacinski later showed that cells which could contribute to the mesoderm were located on the surface of the embryo at the onset of gastrulation, whereas Lundmark showed that both surface-layer and deep cells from late blastula embryos could contribute to the mesoderm. However, neither of the latter studies addressed Løvtrup's proposal that deep cells contributing to the mesoderm originated from the blastocoel roof. In this study, we tested this idea by injecting an lacZ-fusion construct into the upper tier of cells of 32-cell embryos and following the fate of these cells. As a control, third-tier cells, which should include both deep and superficial marginal-zone cells, were also injected with the lacZ construct. Our results show that third-tier cells contribute to the mesoderm, as expected; however, first-tier cells do not, although we do observe labelled cells in the process of dropping into the blastocoel.
Changes in esterases during early embryonic development of Barytelphusa guerini (H. Milne Edwards)
Authors: Lakshmipathi V. , Sujatha M.
Published: August 2008

Quantitative and qualitative changes in the levels of activity of esterases are studied in five stages of developing embryos of the freshwater crab Barytelphusa guerini. Esterase activity levels increase enormously as development progresses. Electrophoresis on 7.5% polyacrylamide disc gels reveals seven zones of esterase active bands. Only two of the seven zones of esterases are present in all five stages. These bands show an increase in their activity in stages III–V. Substrate specificity and inhibitor sensitivity of the enzymes were used to classify esterases. The twofold serial dilution technique was employed to estimate the relative proportion of each esterase band observed during electrophoresis. Heat denaturation studies indicate an increase in the thermal stability of the enzyme as development progresses.
Mitochondrial and nuclear genetic relationships of deer (Odocoileus spp.) in western North America
Authors: Cronin Matthew A.
Published: August 2008

Odocoileus hemionus (mule deer and black-tailed deer) and Odocoileus virginanus (white-tailed deer) are sympatric in western North America and are characterized by distinct morphology, behavior, and allozyme allele frequencies. However, there is discordance among nuclear and mitochondrial genetic relationships, as mule deer (O. h. hemionus) and white-tailed deer have similar mitochondrial DNA (mtDNA) which is very different from that of black-tailed deer (O. h. columbianus, O. h. sitkensis). I expanded previous studies to clarify the genetic relationships of these groups by determining mtDNA haplotype and allozyme genotypes for 667 deer from several locations in northwestern North America. Different mtDNA haplotypes in mule deer, black-tailed deer, and white-tailed deer indicate that mitochondrial gene flow is restricted. Allozyme allele frequencies indicate that there is also restriction of nuclear gene flow between O. virginianus and O. hemionus, and to a lesser extent between mule deer and black-tailed deer. There is a low level of introgressive hybridization of mtDNA from mule deer and black-tailed deer into white-tailed deer populations and considerable interbreeding of mule deer and black-tailed deer in a contact zone. The discordance of mitochondrial and nuclear genomes is apparent only if mtDNA sequence divergences, and not haplotype frequencies, are considered.
Biological and genetic study on the utilization of Solanum berthaultii Hawkes by the Colorado potato beetle (Leptinotarsa decemlineata (Say))
Authors: Pelletier Yvan , Smilowitz Zane
Published: August 2008

Solanum berthaultii Hawkes is used in some potato breeding programs because of its resistance to insects. This close relative of Solanum tuberosum L. may eventually be introduced as a hybrid with the potato, in the geographic distribution of the Colorado potato beetle. To evaluate the fate of such a resistant variety derived from S. berthaultii, the biological performance and the genetic potential for adaptation of the Colorado potato beetle on S. berthaultii has been evaluated. Survival, developmental time, prepupal weight, fecundity, and egg weight were the fitness parameters considered. Survival and fecundity were reduced and more variable on S. berthaultii than on S. tuberosum, but developmental time and prepupal weight were similar on both plant species. The egg weight was not affected by the plant species or the parentage and did not influence the larval fitness parameters. For all the fitness parameters studied, except egg weight, a significant effect of the "Host × Sire" component was observed, indicating a difference in the effect of the plant species between insect families. However, this interaction had an additive genetic basis only for fecundity and possibly survival. Fecundity had a significant additive genetic component only on S. berthaultii. The important covariance of the survival between plant species and the negative covariance between fecundity and survival on S. berthaultii support the hypothesis that the Colorado potato beetle would have a lower rate of increase on S. berthaultii. Our results indicated that specialization of the Colorado potato beetle on S. berthaultii is possible but should not influence its performance on S. tuberosum.
Food consumption of wintering harp seals, Phoca groenlandica, in the St. Lawrence estuary, Canada
Authors: Murie D. J. , Lavigne D. M.
Published: August 2008

Diet composition and rates of food consumption were determined for 25 harp seals (Phoca groenlandica) wintering in the St. Lawrence estuary, Canada, in January and February 1983. Capelin (Mallotus villosus) was the predominant food item in stomachs (100% frequency of occurrence, 86% numerical abundance, 77% mass, 86% gross energy). Juvenile harp seals (mean mass = 64 ± 12 kg, n = 8) consumed 2.0 ± 0.6% of their total mass or 4.2 ± 1.4% of their core mass in fish daily, from which they obtained 3065 ± 1096 kcal∙d−1. Mature harp seals (mean mass = 134 ± 28 kg, n = 17) consumed fish equivalent to 1.8 ± 1.0% of total body mass or 3.6 ± 2.1% of core body mass and acquired 5226 ± 2700 kcal∙d−1. Food consumption did not vary with sex or maturity status when adjusted for differences in body size (analysis of covariance, P > 0.30).
Influence of foraging ecology on alimentary tract size and function of Svalbard reindeer
Authors: Staaland Hans , White Robert G.
Published: August 2008

Insular, high arctic Svalbard reindeer (Rangifer rarandus platyrhnchus) appear better adapted to digesting grasses, sedges, and mosses than mainland reindeer and caribou (R. t. tarandu, R. t. granti, R. t. groenlandicus). We investigated the extent to which dietary differences are related to alimentary tract morphology and function. Concentration gradients of nutrients in the alimentary tract of Svalbard reindeer follow a similar pattern to that found in Norwegian domestic reindeer. Alimentary pools sizes of total digesta, water, Na, K, and P increased with body weight, and the rumen–reticulum dominated as the major compartment of the alimentary tract. In Svalbard reindeer, cecal nutrient pool sizes were relatively larger in winter than summer (P < 0.05) for all nutrients except P. Relative weight of cecal contents (% body weight) of Svalbard reindeer exceeded that of Norwegian reindeer in summer, and a further significant increase (P < 0.05) was noted in winter. Volatile fatty acid levels and molar proportions in Svalbard reindeer suggest low cellulolytic activity in the rumen and high fiber, low sugar fermentation in the cecum. The relatively large winter cecum size in Svalbard reindeer modulates the seasonal decline in volatile fatty acid production and allows for high rates of nonprotein N, water, and mineral absorption. Results support the "grazer" hypothesis applied to Svalbard reindeer in the winter period, but not in summer.
Variation in DNA content among age classes of broad whitefish (Coregonus nasus) from the Sagavanirktok River delta
Authors: Lockwood Samuel F. , Seavey Brent T. , Dillinger Jr. Robert E. , Bickham John W.
Published: August 2008

Variation in cellular DNA content between age-classes was measured in 111 individuals of the Sagavanirktok River delta population of the broad whitefish, Coregonus nasus, using flow cytometry. Mean DNA content for the species was 7.07 pg. Deviations from normal distributions were found within age-class samples and for the entire sample. Intraspecific variation exceeding 75% of mean genome size, nearly twice that found in studies of other vertebrates, was most similar to that found in a study of coastal samples of a congener, the Arctic cisco (Coregonus autumnalis). This study illustrates the need for large sample sizes to account for karyotypic variability and population structure when reporting DNA content values for individual taxa.
Histochemical identification of ovarian lipids during vitellogenesis in the lizard Lacerta vivipara
Authors: Gavaud Jacqueline
Published: August 2008

Histochemical identification of lipids was performed on frozen sections of ovary and liver throughout thermal-induced vitellogenesis in the lizard Lacerta vivipara. Two classes of lipids were identified in both organs: triglycerides and phospholipids. The former are in a fluid state (stained by Sudan Black B), neutral (Nile Blue method), and unsaturated (reduce OsO4). The latter react to a dichromate–hematoxylin method and are acidic (Nile Blue method). Throughout vitellogenic growth, oocytes simultaneously accumulate triglyceride and phospholipids linked to polypeptide granules. Both types of lipid inclusions always remain distinct.