bluuebunny/crossref_metadata_2025 huggingface dataset:
Thyroxine: effect on behavioral thermoregulation in fishes
Authors: Reynolds William W. , Casterlin Martha E. , Spieler Richard E.
Published: August 2008

Exposure to thyroxine in the ambient water significantly lowered the preferred temperatures of two fish species. Acute exposure to thyroxine at a concentration of 20 μg/L of water lowered the preferred temperature by approximately 2 °C, while chronic exposure to the same concentration for 14 days prior to testing lowered the preferred temperature by as much as 10 °C. Chronic exposure for 14 days to thiourea (0.33 g/L), a thyroxine antagonist, raised the preferred temperature by 2.6 °C. These results suggest a role of thyroid hormones in thermoregulatory behavior of ectothermic vertebrates.
Effects of castration on growth and food intake cycles in young male reindeer (Rangifer tarandus tarandus)
Authors: Ryg Morten , Jacobsen Endre
Published: August 2008

To establish whether testicular factors are essential for the regulation of the growth cycle of reindeer, we investigated changes in food intake and body weight in intact and castrated males from March to December. The castrates gained less weight than the intact animals during summer, and during late summer food intake was lower in the castrates. During late September and early October, coinciding with testosterone peaks, the intact animals lost weight, whereas the weight of the castrates was stable. In spite of these differences, cyclic changes in food intake and rate of weight gain was seen also in the castrates. The regulation of the growth cycle in male reindeer can therefore only partly be dependent on testicular factors.
The relation between worker numbers and the production of males and queens in the bumble bee Bombus perplexus
Authors: Pomeroy N. , Plowright R. C.
Published: August 2008

The first-brood worker populations of 18 artificially fed colonies of Bombus perplexus were adjusted to two, four, or eight and allowed to treble with the emergence of the second brood. The timing of male production was independent of the number of workers present and independent of the time of colony initiation. Consequently the duration of the premale period was correlated with the earliness of colony initiation. The first queens emerged after a mean delay of 3.2 days after the first males, this delay being shorter if more workers were present. The rate of pollen consumption per unit larval area was lower with only two workers present than when there were four or eight, but no association was found between the time of initiation of queen production and high ratios of worker numbers to larval area.
Cyclic AMP and cyclic GMP levels in regenerating adult newt forelimbs following anaesthetization
Authors: McLaughlin Hooley M. G. , Liversage Richard A. , Rathbone Michel P. , McLaughlin Danielle S.
Published: August 2008

Levels of cyclic AMP and cyclic GMP in adult newt (Notophthalmus viridescens) intact and 22- and 35-day regenerate forelimbs were studied, as were the levels in the contralateral intact forelimbs and hind limbs. MS 222 anaesthetization results were compared with those of liquid nitrogen fixation. We observed an elevation in the levels of cAMP in animals having undergone MS 222 anaesthetization as compared with those immersed in liquid nitrogen. Cyclic GMP levels appear to be comparatively unaffected. Both the anaesthetic and liquid nitrogen animal series displayed differences in cAMP and cGMP levels according to the particular tissue sample taken and the stage of regeneration.
Structure of the cocoon of the neotropical bumblebee Bombus atratus Franklin
Authors: Mello Maria Luiza S.
Published: August 2008

The cocoon of Bombus atratus was studied using cytochemical methods and polarization microscopy. The aims were to investigate the components of the cocoon and to establish their stereoarrangement in the cocoon wall. Filamentous layers assumed to be composed of the structural proteins produced by the silk glands appear to make up the framework of the whole structure. They are arranged nearly parallel to the cocoon's surface and depict some reorientation of their protein macromolecules when compared with the situation found in the lumen of the silk glands. These layers enclose masses of pollen grain remnants excreted by the larvae as it spun the cocoon. The pollen grains are stuck together by a mucus which has the cytochemical and some of the anisotropic properties of the secretion discharged by the Malpighian tubules of the larva. Mucous layers, assumed to be produced by the silk glands, cover the cocoon externally. Eventually they also appear associated with the inner filamentous layers. Urate crystal units, sometimes containing acid glycosaminoglycans in their cores, occur in the cocoon wall and come from the Malpighian tubules. The cocoon of B. atratus is not impregnated with calcium.
Evolution in the Annelida
Authors: Brinkhurst Ralph O.
Published: August 2008

The aquatic Oligochaeta as well as the earthworms can be derived from ancestors closely resembling living Haplotaxidae. Four of the five required intermediate forms are represented by living haplotaxid species. The polychaetes are also thought to be derived from simple earthworm-like forms. These concepts are in accord with recent locomotor theory separating the evolution of the coelom and segmentation as a two-step process related to sustained burrowing activity, as opposed to the earlier complex of theories involving the simultaneous evolution of coelom and segmentation. Unsegmented coelomates are seen as representatives of an intermediate condition between acoelomates and segmented coelomates instead of problem phyla derived by degeneration of segmented ancestors.
Territoriality in adult female Columbian ground squirrels
Authors: Festa-Bianchet Marco , Boag David A.
Published: August 2008

The spatial relationships among adult female Columbian ground squirrels (Spermophilus columbianus) were investigated through intensive behavioral observations at an isolated, high-density colony in southwestern Alberta in 1979 and 1980. Population size at spring emergence more than doubled during the study mainly through an increase in number of yearlings. Each adult female established a small home range and actively defended part of it as a territory. All intruding females were chased out, but exclusive use was not achieved. Territorial behavior increased after breeding, declined during late gestation, peaked during lactation, and decreased again after juveniles emerged. The adaptive significance of female territoriality seems to be related mainly to protection of juveniles.
Measurement and estimation of functional proboscis length in bumblebees (Hymenoptera: Apidae)
Authors: Harder Lawrence D.
Published: August 2008

Analysis of a 16-mm cinefilm of feeding bumblebees (Bombus) indicated that the glossa is the functional unit of proboscis length. This was corroborated by observations of the depth to which wild bees probed Impatiens biflora and by data presented in the literature. Accurate measurement of the glossa length of bees that died with their proboscides folded is facilitated by straightening the labium by dissection. Regression equations describing the relation between glossa and wing length, derived from bees from a single colony, provide sufficient accuracy to allow prediction of glossa length for that species in a field study.
Weight and feather growth of nestling tree swallows
Authors: Zach Reto , Mayoh Keith R.
Published: August 2008

Six models were tested for weight and feather growth of nestling tree swallows (Iridoprocne bicolor). The logistic model, with an asymptotic weight A of 22.4 g and a growth-rate constant K of 0.51 day−1, was most appropriate for weight growth. Observed curves for individual birds were of diverse shape and some lacked weight recession. Growth of primary feather 9 and rectrix feather 6 followed the Gompertz model, with A and K values of 80.9 and 49.6 mm, and 0.21 and 0.20 day−1, respectively. Fitting of the models to feather length was complicated because growth curves for individual birds did not coincide in time, and fledging occurred before completion of growth. Long nestling times were associated with slow weight and feather growth, and A and K were consistently negatively correlated. The variation of A, K, and nestling time among broods ranged from 49.2 to 95.1%, and brood size could not account for much of the observed variability. Presumably, various nest-box variables and weather conditions as related to the age of nestlings are important. Primary and rectrix growth were similar and closely linked but apparently unrelated to weight growth. Growth of feather vanes was closely linked to feather growth. Birds that failed to fledge had depressed weight, feather, and vane growth. Weight growth and recession seem to be particularly well suited for investigating natural and man-made environmental stresses.
Paired impulses in lobster claw motoneurons: in vitro and in vivo production
Authors: Govind C. K. , Hill R. H.
Published: August 2008

The somata of the claw opener excitor (OE), the slow closer excitor (SCE), and the fast closer excitor (FCE) motoneurons were physiologically identified in the lobster, Homarus americanus, using an isolated claw ganglion preparation. Depolarization of the soma produced paired impulses with an interpulse interval of 10–12 ms, which demonstrates that doublet production is an intrinsic motoneuron property. Similar paired impulses were found for the FCE axon in intact lobsters where they occurred with a shorter interpulse interval for the cutter than for the crusher claw.
Testicular development and spermatogenesis in Calpodes ethlius Stoll (Hesperiidae, Lepidoptera)
Authors: Lai-Fook J.
Published: August 2008

Some general features of the internal male reproductive system of Calpodes ethlius are described. The visibility of the testes through the transparent integument makes males distinguishable from hatching to the midpupal stage. The paired larval testes fuse at metamorphosis into a single adult testis. The major nongerminal cells of the testis consist of an outer capsule layer and an inner follicular layer which also extends inwards as septa separating the follicles. The cells of these two layers undergo extensive changes in shape and contents throughout larval life and during metamorphosis. Meiosis begins during the third larval instar with development of primary spermatocytes, followed by preparation for first meiotic division. Six spermatogonial and two meiotic divisions give rise to 256 sperm per cyst. Eight cyst cells are present in each cyst. Eupyrene spermatids first appear about 24 h before ecdysis into the last (fifth) larval instar, and apyrene spermatids in the early wax-secreting fifth larva. Both kinds of spermatids continue to be produced in approximately the same relative proportions throughout the pupal and adult stages.
Structure of the noncuticular simplex of the internal male reproductive tract of Calpodes ethlius (Hesperiidae, Lepidoptera)
Authors: Lai-Fook J.
Published: August 2008

The ductus ejaculatorius simplex (simplex) of the reproductive tract of the adult male of Calpodes ethlius is separated by distinct constrictions into seven segments, varying in length from 0.24 to 19.3 mm and totalling 4 cm. Two of the segments, S1 and S5, are further divisible into three and two parts, respectively, on the basis of either cellular structure or secretory products. The most distinctive region is the most anterior one which is made up of two distinctly different cells, one a merocrine secretory cell which resembles the cells of all other regions, and the other an apocrine secretory cell whose highly modified apical region is sloughed upon copulation. All segments are surrounded by two layers of muscle, a thin, inner circular layer and a more robust, outer longitudinal layer, which are supplied with tracheoles and nerves. Tracheoles also penetrate the epithelium of segment seven. The merocrine secretory cells of all segments are similar in that they all have well-developed endoplasmic reticulum, numerous Golgi and mitochondria, and a microvillate apical surface. Nonetheless, the cells of each segment are distinguished by some feature of either their structure or their secretions.
Structural comparison between eupyrene and apyrene spermiogenesis in Calpodes ethlius (Hesperiidae, Lepidoptera)
Authors: Lai-Fook J.
Published: August 2008

Calpodes ethlius, like other Lepidoptera, produce two kinds of sperm, nucleated eupyrene and anucleated apyrene. The latter lack not only a nucleus but also reticular lacinate appendages at maturity in the testis. It is, however, possible to distinguish between them much earlier as secondary spermatocytes. The larger eupyrene spermatocytes have larger, spherical nuclei with dispersed chromatin, while the smaller apyrene spermatocytes have smaller more oval nuclei with clumped chromatin. A more extensive perinuclear reticular system surrounds the eupyrene nucleus. The nucleus of the eupyrene spermatid is small with condensed chromatin; however, the apyrene spermatid contains many micronuclei which are later cytolysed and eliminated. An acrosome forms in the eupyrene spermatid and differentiates into a tubular structure which extends along the elongating nucleus, in which the chromatin simultaneously undergoes characteristic changes in distribution and condensation. The reticular appendage first appears extracellularly where the acrosome makes contact with the plasma membrane, and later extends the full length of the sperm. The lacinate appendages appear much later, after elongation of head and of the tail are completed. The mature testicular sperm are distinguishable on the basis of detailed differences in mitochondrial derivatives, and axonemal structure. The free apyrene sperm undergo fewer changes than do the still encysted eupyrene sperm as they pass from the testis into the reproductive tract and finally into the bursa copulatrix of the female.
Oxygen uptake in a barnacle: scaling to body size from nauplius to adult
Authors: Jorgensen D. D. , Vernberg W. B.
Published: August 2008

We measured the oxygen uptake of the barnacle Balanus eburneus Gould during the following stages of its life cycle: (1) naupliar stages 1, 4 and 6; (2) cyprid; (3) postmetamorphosis adult (pinhead); and (4) large adult. Mass specific oxygen uptake [Formula: see text] increased by 60% during development from naupliar stage 1 to stage 6. An eightfold drop in [Formula: see text] occurred with the molt from stage 6 to cyprid. [Formula: see text] increased by fourfold after metamorphosis of the cyprid into the pinhead, the smallest adult. The slopes of the regression lines describing the relationship between nonmass specific O2 uptake and dry body weight (Wb) were (1) 1.27 for nauplii, (2) 0.87 for large adults, and (3) 0.75 for all life cycle stages studied except cyprids.
The leg muscles of the American coot (Fulica americana Gmelin)
Authors: Rosser Benjamin W. C. , Secoy D. M. , Riegert P. W.
Published: August 2008

The gross anatomy of all the leg muscles of the American coot (Fulica americana Gmelin) is described. These findings differ on a number of points from earlier investigations of gruiform anatomy: the presence of M. iliotrochantericus medius, the presence of two heads and one inserting tendon of M. femorotibialis internus, the presence of M. gastrocnemius pars intermedia, the presence of two heads of M. flexor perforatus digiti II, the presence of M. extensor hallucis longus pars distalis, the belly of M. adductor digiti II extending for most of the tarsometatarsal length, the belly of M. abductor digiti IV confined to the distal half of the tarsometatarsus, the rudimentary presence of M. adductor digiti IV, and the absence of patellae. Unique to F. americana within the few gruiforms that have been studied is a longitudinal division in the superficial side of M. gastrocnemius pars interna. The species has adaptations associated with swimming and diving; the muscles that flex and extend the tarsometatarsus and the third digit are well developed.
Some ultrastructural features of the nuchal organ of Daphnia magna Straus (Crustacea: Branchiopoda)
Authors: Halcrow K.
Published: August 2008

The ultrastructure of the nuchal organ of first instar of Daphnia magna is similar to that described in the literature for presumed ion-transporting tissues in other crustaceans. The apical and basal plasma membranes are extensively amplified through microvilli and infoldings; mitochondria are abundant and distributed unequally between the two types of cells (dark and light) composing the organ, more being present in the dark cells. The two cell types differ also in the type of microvilli projecting from their apical surface. In proecdysis these microvilli are replaced by much smaller ones which are associated with the deposition of the new cuticle.
Food habits of mink (Mustela vison) and otter (Lutra canadensis) in northeastern Alberta
Authors: Gilbert F. F. , Nancekivell E. G.
Published: August 2008

Scats of mink (Mustela vison) and otter (Lutra canadensis) in northeastern Alberta contained different food items in different habitat types according to type of water body. Brook stickleback (Culaea inconstans) was the most frequently encountered food item in scats of both species from a drainage system dominated by lakes and for otter from a second drainage system dominated by streams. However, mink had varying hare (Lepus americanus) as their primary food item by frequency of occurrence in this latter situation and mammalian items were significantly (P < 0.01) more frequent. Otter scats contained more fish and invertebrates (P < 0.01) and fewer mammals (P < 0.01) and birds (P < 0.05) than mink scats. Both otters and mink appeared to exploit avian species to a greater degree (P < 0.01) in the lake-dominated drainage. The frequency of avain remains in otter scats was very high and probably reflected high utilization of breeding and moulting waterfowl.
A laboratory study of the feeding behavior of the rhabdocoel Mesostoma ehrenbergii on pond Cladocera
Authors: Schwartz Steven S. , Hebert Paul D. N.
Published: August 2008

The predation rates of the rhabdocoel Mesostoma ehrenbergii were determined on a number of cladoceran species. Two means of capturing prey are employed by the flatworm but only active predation was explored in these experiments. It was found that this flatworm is a size-dependent predator with a preference for prey of about 1.2 mm. It was also observed that prey behavior was not an important factor in determining susceptibility to predation. M. ehrenbergii is a voracious predator; individuals consume more than 10 prey/day.
Resource partitioning in the carrion beetle (Coleoptera:Silphidae) fauna of southern Ontario: ecological and evolutionary considerations
Authors: Anderson Robert S.
Published: August 2008

Resource partitioning in the silphid fauna of southern Ontario is examined in detail, using baited pitfall traps placed in four different habitats. During 1979 and 1980, a total of 9549 specimens of Silphidae were collected, representing 12 species, of which 5 were in the subfamily Silphinae and 7 in the subfamily Nicrophorinae. The roles of different seasonal patterns, habitat specificity, and food type and size in resource partitioning are discussed for all species. At the subfamilial level, resource partitioning is accomplished through selection of different sizes of carcasses, while at the specific level, seasonal patterns and habitat specificity appear to be the primary means permitting coexistence.In the Silphidae, competition for food resources appears to be the primary factor inducing ecological character displacement. The possible origins of patterns of resource use in this assemblage are discussed in an ecological and geological time framework.
Median length at sexual maturity of halibut, cusk, longhorn sculpin, ocean pout, and sea raven in the Maritimes area of the Northwest Atlantic
Authors: Beacham Terry D.
Published: August 2008

The length at which 50% of the individuals were mature was calculated for some Northwest Atlantic groundfish species. Median length at maturity for halibut (Hippoglossus hippoglossus) on the Scotian Shelf declined from 84 cm for males during 1959–1964 to 66 cm during 1970–1979. Median lengths at maturity for females declined from 98 to 70 cm. Ranges of median lengths (centimetres) at maturity for other species were as follows: cusk (Brosme brosme), male 48–56, female 47–56; longhorn sculpin (Myoxocephalus octodecemspinosus), male 24–29, female 23–25; ocean pout (Macrozoarces americanus), male 45, female 28; and sea raven (Hemitripterus americanus), male 36, female 28.
The distribution, biology, and status of the fishes Campostoma anomalum, Clinostomus elongatus, Notropis photogenis (Cyprinidae), and Fundulus notatus (Cyprinodontidae) in Canada
Authors: McKee Paul M. , Parker Bradley J.
Published: August 2008

Campostoma anomalum, Clinostomus elongatus, Notropis photogenis, and Fundulus notatus in Canada are confined to a few streams in southern Ontario and are considered rare or threatened in this country. The distribution of C. anomalum shows dramatic expansion in the Thames River drainage over the past decade. Clinostomus elongatus has a disjunct distribution and has apparently been extirpated from several watersheds owing to habitat degradation. Information on the stability of N. photogenis and F. notatus populations is lacking. Both C. anomalum and N. photogenis are rheophilic and occur in relatively high gradient streams. Clinostomus elongatus occurs mainly in cool, clear headwaters. Fundulus notatus is confined to turbid and sluggish or stagnant streams. Factors affecting the vulnerability of these species, based on habitat requirements, are described and measures to conserve their habitats are suggested. Observations on growth, reproduction, feeding, predation, and parasitism are also described.
Feeding activity of ducks in relation to diel emergence of chironomids
Authors: Sjöberg Kjell , Danell Kjell
Published: August 2008

The diel emergence of chironomids, an insect group important as food item for both adult and young ducks, was studied in relation to the feeding activity and behaviour of ducks on a northern Swedish lake (66°3′ N, 23°46′ E) during 1975–1978. Emergence and swarming activity of chironomids peaked between 0800 and 1200. Emergence occurred even on windy days, but almost completely ceased during periods of rainy and cold weather. Swarming occurred mainly around 1000 on warm days with little or no wind. During such occasions, a large number of chironomids were observed over the entire surface of the lake. Dabbling ducks fed throughout a 24-h period, but peak feeding coincided with periods of chironomid emergence. Surface feeding by both dabbling and diving ducks on chironomid imagines present on the water surface and on emergent vegetation increased during these periods of chironomid emergence.
Structure and behavior of white pelican formation flocks
Authors: O'Malley J. Brian E. , Evans Roger M.
Published: August 2008

Observations of white pelicans commuting between nesting colonies and foraging areas revealed transitions from small, simple linear flock formations to larger, more complex vee and jay formations during departures, and the reverse during the return approach. Large, less-organized types of formations were relatively uncommon and short lived.Formation angles measured for filmed flocks ranged from 24° to 122° and were highly correlated with mean relative interbird distances within flocks. The number of wingbeats per hour, calculated from wingbeat frequency (beats per minute) and percent time flapping, was lowest in vee formation, progressively greater in jay, echelon, and column formation, and greatest for single birds. Wingbeats per hour decreased behind the lead bird, which usually had the highest rate, within each type of formation.Shifts between flapping and gliding were usually initiated by lead birds. Response times for these shifts were negatively related to flock size, and were shorter in vee and jay formations than in column and echelon formations.Our data suggests formation flight provides both aerodynamic–energetic and communication advantages over solitary flight.
Monoamine transmitters and cAMP stimulation of Na transport in freshwater mussels
Authors: Dietz Thomas H. , Scheide John I. , Saintsing David G.
Published: August 2008

The unionid mussels Ligumia subrostrata and Carunculina texasensis maintain a sodium steady state in artificial pond water. When the mussels were injected with serotonin, catecholamines, or phenylephrine (< 2 × 10−5 M/L blood), the influx of Na was elevated 150–220% above controls and the animals accumulated Na from the medium. A similar response was observed with injections of dibutyryl cyclic AMP. Isolated gills of mussels accumulate Na from a pond-water bathing medium and the Na transport rate was stimulated by serotonin but not catecholamines. Serotonin was present in the gill tissue (2.26 ± 0.18 μg/g wet gill). Serotonergic neurons innervated by adrenergic fibers may be directly stimulating the Na transporting tissues in the gill of freshwater mussels.
Energy expenditure in free-ranging sagebrush lizards (Sceloporus graciosus)
Authors: Congdon Justin D. , Tinkle Donald W.
Published: August 2008

Metabolic rates of free-ranging Sceloporus graciosus (Sauria: Iguanidae) were measured during the summer using doubly labeled H2O. Adults of either sex and juveniles did not differ in field metabolic rates (0.26 mL CO2∙g−1∙h−1or 160 J∙g−1∙day−1). Field metabolic rates were 2.4 times the resting metabolic rate, and activity respiration was 3.1 times the resting metabolic rate at lizard activity temperatures. Activity accounted for 59% of the energy consumption due to respiration. Calculated rates of feeding indicated a 415 J∙day−1 deficit in metabolizable energy intake, and this was reflected in rate of loss of body mass throughout the study. Daily energy harvested by 200 lizards (31 kJ∙day−1), which approximates densities (per hectare) on the study area, would supply only 40% of the daily energy requirements of one insectivorous bird with similar body mass and activity level of a Phainopepla (79 kJ∙day−1).
Responses of Cyclops bicuspidatus thomasi to alterations in food and predators
Authors: Peacock Adrienne
Published: August 2008

When Cyclops bicuspidatus thomasi was transplanted from Placid Lake (where C. b. thomasi was abundant) to enclosures in Gwendoline Lake where C. b. thomasi was rare, this species was able to grow, survive, and reproduce in Gwendoline Lake water with Gwendoline Lake crustacean plankton. Fertilization of a Gwendoline Lake enclosure increased the survivorship of C. b. thomasi about 22% over that observed in the unfertilized treatment. However, addition of the midge fly larvae common to Gwendoline Lake (C. trivittatus and C. americanus) to the enclosure plankton community resulted in a decrease in the standing crop of C. b. thomasi to a point at which samples with C. b. thomasi became difficult to obtain. When Chaoborus was in the enclosure, fertilization did not enhance the abundance of C. b. thomasi but rather improved the survivorship of Chaoborus first and second instar larvae, and this resulted in an acceleration of the C. b. thomasi nauplii decline.
Two new South Pacific fishes of the genus Ebinania and contributions to the systematics of Psychrolutidae (Scorpaeniformes)
Authors: Nelson Joseph S.
Published: August 2008

Two new species of Psychrolutidae from the South Pacific are described: Ebinania macquariensis n. sp. and Ebinania malacocephala n. sp. Both species are known only from the holotypes, which are deposited in the Natural History Museum Los Angeles County (LACM 10984-1 and LACM 10936-2). The Psychrolutidae are redefined, the systematics of the family and of some of its species are discussed, and a preliminary classification of the family based on a study of 15 species, emphasizing the arches of bone over the lateral line system of the head, is presented. The genus Cottunculus is polyphyletic and should be limited to the "hard-headed" members, C. microps, C. sadko, C. granulosus, and C. thompsoni. The "soft-headed" members, C. brephocephalus of Japan and C. costaecanarie from western Africa (which is recognized as a valid species and studied from new material and the holotype), are placed in the genus Ebinania. Two lineages of psychrolutids are provisionally recognized as follows: (i) the "hard-headed" forms (using adult material) of the subfamily Cottunculinae with Malacocottus, Dasycottus, Cottunculus, Eurymen, and two species formerly placed in Neophrynichthys, and (ii) the "soft-headed" forms of the subfamily Psychrolutinae with Ebinania, Psychrolutes, and Neophrynichthys. The genus Psychrolutes is expanded and recognized to have two relatively distant subgenera; P. (= Gilbertidia) sigalutes shares several osteological characters with P. paradoxus and is placed in the same subgenus, Psychrolutes, while P. (= Cottunculoides) inermis and P. marcidus (formerly placed in Neophrynichthys) are placed in a second subgenus, Cottunculoides, along with P. phrictus and P. sio. A key to the species of the family is presented.
A methemoglobin reductase system in channel catfish Ictalurus punctatus
Authors: Huey David W. , Beitinger Thomas L.
Published: August 2008

A modified spot screening test for methemoglobin reductase (MHb reductase), indicated that this enzyme occurs in channel catfish, Ictalurus punctatus. The presence of MHb reductase offers at least a partial explanation of the rapid recovery observed when catfish with profound nitrite-induced methemoglobinemia are placed in nitrite-free water.
A review of the ectoparasitic Leptinus beetles of North America (Coleoptera: Leptinidae)
Authors: Peck Stewart B.
Published: August 2008

Leptinus beetles are facultative ectoparasites known to occur on 18 species of small mammals in North America. Leptinus americanus is restricted to the central United States, west of the Mississippi River. Its hosts and seasonality are unknown. Leptinus orientamericanus n.sp. is widespread east of the Mississippi River. It occurs on seven hosts, most frequently on Blarina brevicauda and Scalopus aquaticus and during fall and winter months. Leptinus occidentamericanus n.sp. has a range in western North America from California to Alaska and the Yukon. It occurs on 11 hosts, most frequently on Sorex trowbridgii, and during spring and fall months. A hypothesis of evolution is given for all nine species in the genus. It suggests a Palaearctic origin for the family and genus and an early Tertiary entry to North America by a Bering land bridge.
Ultrastructure of the larval antenna of Tenebrio molitor L. (Coleoptera: Tenebrionidae): structure of the blunt-tipped peg and papillate sensilla
Authors: Bloom J. W. , Zacharuk R. Y. , Holodniuk A. E.
Published: August 2008

Each antenna of a final instar Tenebrio molitor larva has two blunt-tipped pegs and two papillate sensilla. The former are short pegs with fluted cuticle and a terminal moulting pore and are set in deep sockets. Two large microtubule-filled dendrites fill a dense dendritic sheath within the peg; below the base of the peg they are joined by a lamellate dendrite and a dendrite resembling a scolopidial cilium. There are four accessory cells, the innermost resembling a scolopale cell. This sensillum may be thermo- and hygro-receptive.Superficially the papillate sensillum is radially symmetrical with a central zone of small cuticular papillae surrounded by one or two rings of smooth cuticle. Three or four dendrites (of five) end under a turret of longer papillae at the center of the papillate cuticle. Fine pores from the dendritic canal extend to the surface between the papillae. One or two dendrites, one of which may be lamellate, end well below the end organ. There are five accessory cells. The sensillar and ciliary sinuses are large and the bounding membranes of the sheath cells highly elaborated. The function of this sensillum is uncertain.
Behavior and life history of Leucotrichia pictipes (Banks) (Trichoptera:Hydroptilidae) with special emphasis on case reoccupancy
Authors: McAuliffe Joseph R.
Published: August 2008

Leucotrichia pictipes (Banks) has a univoltine life cycle in Owl Creek, a western Montana stream. Early instar (I–IV) larvae appear in mid-July and case acquisition by instar V larvae occurs during July and August. Larvae overwinter in cases and adults emerge the following June and July. Emerging pupae cut round emergence holes at one end of their cases. These old cases remain unoccupied for several weeks but then are reinhabited by the next generation of larvae. Over 75% of cases are reoccupied in this manner. A small proportion of old cases is also occupied by other invertebrates such as early instar hydropsychids. If old cases are not available, newly molted instar V larvae construct new cases. The numerical dominance of Leucotrichia in Owl Creek may be due to its ability to reoccupy old cases as well as to occupy new space by constructing new cases.
Energetic reserves of Hudson Bay willow ptarmigan during winter and spring
Authors: Thomas Vernon G.
Published: August 2008

Willow ptarmigan (Lagopus lagopus) were collected from the Hudson Bay coast of Ontario from February to June, and the proximate composition and tissue composition of the carcasses were analysed. Total carcass composition remained uniform from February to late May. The neutral fat level remained low at approximately 2% of body weight. The total energy reserve from neutral fat and labile protein was calculated to be 165 and 180 kcal (1 kcal = 4.1868 kJ), respectively, for a 550-g female and a 600-g male ptarmigan. Gonadal recrudescence began in early May, but its extent was not correlated significantly with change in body weight or carcass neutral fat content. The low neutral fat levels observed during winter and the onset of reproduction indicate that this population is dependent upon its immediate food supply for both winter survival and clutch formation.
Habitat and food resource partitioning among four species of darters (Percidae: Etheostoma) in a southern Ontario stream
Authors: Paine Michael D. , Dodson Julian J. , Power Geoffrey
Published: August 2008

Resource partitioning among four species of darters (Percidae: Etheostoma) in an Ontario stream was investigated by determining diet and relative abundance in two habitats. The four species partitioned both food and habitat resources. E. caeruleum and E. flabellare dominated the riffles; the former took prey from rock surfaces, the latter took prey from between and beneath rocks. Etheostoma microperca and E. nigrum dominated the weed beds; the former feeding on prey on and around plants, the latter feeding on benthic prey. Diets were closely related to morphology, but habitat utilization was not. Determining the importance of habitat versus food partitioning is difficult, because microhabitat and foraging habitat may be nearly identical.
A seasonal analysis of small mammal populations on woodlot islands
Authors: Gottfried Bradley M.
Published: August 2008

Ten woodlot islands (surrounded by cornfields) which varied in size and isolation were sampled on a seasonal basis during 1976–1977 to study patterns of small mammal dispersal. The number of small mammal species, density of Peromyscus leucopus, and sex and age ratios of P. leucopus fluctuated on a seasonal basis. During each season island isolation was inversely related to the number of small mammal species and density of P. leucopus. Both island size and isolation were significantly related to density of P. leucopus during the fall. During the winter and spring trapping periods, all P. leucopus on the islands were males. The proportion of males on the islands during the summer and fall was positively related to island isolation. The proportion of adult P. leucopus on the islands was inversely related to isolation during each trapping season.
Life histories of some filter-feeding Trichoptera in Virginia
Authors: Parker Charles R. , Voshell Jr. J. Reese
Published: August 2008

Life histories were determined for seven species of filter-feeding Trichoptera at two sites on the impounded North Anna River and at two sites on the free-flowing South Anna River in the Piedmont of Virginia, U.S.A. Hydropsyche incommoda, H. sparna, and H. venularis were trivoltine at at least three of the four sites, with fast-growing spring and summer generations that matured in June and July, and August and September, respectively, and a slow-growing winter generation that matured in March, April, and May. Cheumatopsyche parentum, Macronema zebratum, Chimarra moselyi, and C. obscura were bivoltine at all sites. The summer generations of these species grew quickly, maturing in June and July, and the winter generation grew slowly, maturing in April and May. Instars I–V, pupae, and adults of most species were present continually from April through October. All species overwintered in instars III–V, and in most species instar II was present during the winter also. Comparisons of Hydropsyche life histories in the Anna Rivers with those reported from other eastern North America rivers reveal that differences in voltinism are probably due to a complex interaction of food quality and temperature regime.
The social system of the coyote (Canis latrans) in a forested habitat
Authors: Messier F. , Barrette C.
Published: August 2008

We studied the social organization of forest-living coyotes (Canis latrans) for 20 months. The four breeding groups in our study area were territorial. The size and shape of their territories remained unchanged despite the sudden and profound change in prey distribution in December as white-tailed deer (Odocoileus virginianus) congregated yearly in a winter yard. Solitary adults lived on overlapping areas that ignored the breeding groups' territories. Some juveniles lived on their parents' territory but were not always associated with them. During the winter (November–April) 35% of the coyotes were in packs of three to five animals, 28% in pairs, and 37% solitary. Animals that were usually solitary almost never congregated to form temporary groups, and members of pairs were almost always together. We conclude that territoriality is essential to insure pup survival by increasing the foraging efficiency of parents that must feed sedentary pups. We suggest that individual and immediate advantage is sufficient to explain the late dispersal of pups resulting in the formation of packs. We therefore question the traditional view that larger group size in coyotes and other social carnivores living in extended families evolved to increase foraging efficiency.
Geometry for the eccentric territory
Authors: Noakes David L. G. , McNicol Richard E.
Published: August 2008

Basic theory predicts that two-dimensional territories should be circular, but results from stream-dwelling juvenile salmonid fishes appear to deviate consistently from such a shape. We present a model for cardioidal territories based on data from juvenile brook charr (Salvelinus fontinalis) and show that circles can be considered as a limiting case for cardioids. Since they are regular geometric shapes directly related to circles, but with one concave side, cardioids may be useful for some analyses of territorial data.
Egg-care behaviour of Aequidens paraguayensis (Pisces, Cichlidae) in relation to predation pressure and spawning substrate
Authors: Dupuis Hélène M. C. , Keenleyside Miles H. A.
Published: August 2008

Aequidens paraguayensis is a cichlid fish with biparental care that spawns on a leaf taken from substrate litter and, after the eggs have hatched, broods the progeny orally. We tested the hypothesis that increasing predator density causes proportional changes in the frequency or duration of parental care activities, including moving the spawn. We predicted that at high predator densities, the parents would pick up the eggs and begin mouthbrooding earlier than usual to prevent egg loss.Increasing predator density led to greater parental sex-role differentiation, the males defending the spawning site while the females tended the eggs. Leaf tugging was performed by the females only and did not increase significantly with predator density. Pairs that spawned on a fixed substrate did not exhibit this sex-role differentiation.Predator density and type of spawning substrate did not affect brood survival or time between spawning and beginning of mouthbrooding. Hatching time is temperature dependent and parents apparently must wait for the egg membranes to break before picking up the hatchlings.
Assessment of telemetric motion sensors for studies of activity
Authors: Garshelis David L. , Quigley Howard B. , Villarrubia Charles R. , Pelton Michael R.
Published: August 2008

Radio transmitters containing motion-sensitive devices that changed the pulse rate (mode) in response to movement were evaluated as a means for studying activity of black bears (Ursus americanus). Two types of motion sensors were used: tip switches gave immediate indications of activity, whereas reset motion sensors extended the active mode signal for 5 min. Locational accuracy was less affected by reset sensors than tip switches, and reset sensors facilitated activity monitoring of weak or fading radio signals. Tip switches were more useful in making continuous judgements of activity, and may be used to differentiate types and degrees of activity. For both sensors true activity could be distinguished from comfort movements. Also, both motion-sensitive transmitters gave indications of activity that compared well with hourly movements of bears; these transmitters were more sensitive to localized movements than measurements between radio locations determined by triangulation and were more practical because only one observer was necessary. Motion sensors also gave more reliable indications of activity than changes in signal integrity.
Flock size and formation in black-billed gulls
Authors: Evans Roger M.
Published: August 2008

Black-billed gulls (Larus bulleri) depart form breeding colonies and foraging sites in nonrandom, clumped formations (flocks). Flocks leaving colonies were significantly smaller than those leaving foraging sites, in part owing to more "upflights" at foraging sites. When more birds left a colony per unit time, flocks were both larger and more frequent.A causal model was developed based on the assumptions that flock departures from a colony or foraging site result from the effects of social attractions superimposed on otherwise random departure intervals. This model successfully predicted the size distribution of flocks departing from four colonies and foraging sites. In conjunction with the concepts of site tenacity and habituation, the model also permits a causal explanation of differences in the size of flocks departing colonies compared with foraging sites, and of size differences in flocks arising from "upflights" as opposed to the more common "straggling" columnar formations. The model and results are consistent with the hypothesis that colonies function as assembly points that facilitate group foraging.
Sexual maturation versus immaturity: different tactics with adaptive values in Baltic salmon (Salmo salar L.) male smolts
Authors: Lundqvist Hans , Fridberg Gunnar
Published: August 2008

Precocious 2-year-old male parr of the Baltic salmon (Salmo salar L.) were retained in freshwater or exposed to brackish water (4.6–5‰) in net pens after smoltification. Comparisons of growth rates and the incidence of sexual maturation revealed great differences between the two groups. In the freshwater group, the growth rate was retarded from mid-July and the fish acquired parr markings. In autumn, they all matured. The group in brackish water became rapidly growing, immature postsmolts. Only 7% matured in the autumn. The increase in mean weight of the postsmolts was 500% from the start of the experiment compared with 90% for the fish retained in freshwater.It is hypothesized that these alternative tactics expressed by salmon male smolts, i.e., sexual maturation combined with a low growth rate while in freshwater compared with sexual immaturity and a high growth rate while in sea, are mutually exclusive. Furthermore, it is suggested that these processes are controlled by annual endogenous rhythms (circannual rhythms) in interaction with the environment–neuroendocrine axis.
Structure, function, and possible evolutionary significance of the constrictions in the male reproductive system of Calpodes ethlius (Hesperiidae, Lepidoptera)
Authors: Lai-Fook J.
Published: August 2008

Distinct constrictions occur between and within the various parts of the male genital tract in Lepidoptera. These consist of an epithelium surrounded by a single inner circular and multiple outer longitudinal layers of muscles. The thicker muscles and the lack of a secretion serve to keep the lumina of the constrictions closed between matings. They are opened by the pressure of secretion being pushed down the tubular tract by muscular action. It is proposed that their development in Lepidoptera has made possible the evolution of accessory glands in series, rather than in parallel, in those situations in which separation of secretory products is required.
The first description of the male and ephippial female of Dadaya macrops (Daday, 1898) (Cladocera, Chydoridae), with additional notes on this common tropical species
Authors: Rajapaksa R. , Fernando C. H.
Published: August 2008

Males and ephippial females of Dadaya macrops (Daday), a widely distributed tropical cladoceran, are described for the first time together with hitherto unrecorded morphological features of the parthenogenetic female. The postabdomen of the male is unique among chydorids in having only a vestige of the terminal claw. This confirms the validity of this monotypic genus. The material studied comes from Sri Lanka (Ceylon), taken in the neighbourhood of the type locality. Our description provides a detailed morphological record of a population containing all instars of males and females, and both parthenogenetic and ephippial adult females. Type material of parthenogenetic females, the only forms hitherto known, agrees closely with our material. An analysis of the population structure is given.
Effets des composés secondaires des plantes sur le poids corporel et le poids de certains organes de la souris de laboratoire
Authors: Bergeron Jean-Marie , Jodoin Louise
Published: August 2008

Seventy species were chosen among the most abundant plants in a typical meadow-vole (Microtus pennsylvanicus) habitat and used in the preparation of experimental diets. Immature female laboratory mice were fed one of the diets for 6 days, and thereafter growth, development of the uterus, and changes in weight of the kidneys and the liver were recorded. Generally, most of the diets retarded growth significantly. Only the diet containing red clover (Trifolium pratense) actually accelerated the development of the uterus in the animals, while 47 other diets significantly decreased the weight of the uterus. Two plants, umbellate aster (Aster umbellatus) and ground-ivy (Glechoma hederacea), killed the animals after 3 or 4 days of treatment. A significant increase in kidney weight and a drastic decrease in liver weight in these two groups of mice was found at autopsy. Many of the diets produced a decrease of liver weight and (or) an increase in kidney weight. Forty-six diets analyzed to determine their effect on liver weight were found to decrease it; 50 of the 70 diets (70%) analyzed to determine their effect on kidney weight were found to increase it. Results are examined in the light of the theory of plant toxicity as a regulatory mechanism in the cycles of small plant-eating mammals.[Traduit par le journal]