bluuebunny/crossref_metadata_2025 huggingface dataset:
Fiabilité des mesures de poids et d'examens histopathologiques dans les études d'intoxication du campagnol des champs (Microtus pennsylvanicus)
Authors: Bergeron Jean-Marie , Jodoin Louise
Published: March 2009

The values of body weight and internal organ weights as indices of the antinutritive properties of certain plants in the diet of meadow voles (Microtus pennsylvanicus) was determined by comparing these measures to results obtained by histological sections of liver and kidney. The white clover (Trifolium repens) diet is the only one to have caused kidney lesions, but diets of timothy (Phleum pratense), reed phalaris (Phalaris arundinacea), simple aster (Aster simplex) or Canada thistle (Cirsium arvense) had considerable effects on the liver. Voles fed ground ivy (Glecoma hederacea) or umbellate aster (Aster umbellatus) had lesions characteristic of periportal interstitial hepatitis that normally results from an irritation. Histological analyses suggested that 10 of the 12 experimental diets had had detrimental effects on the animals, whereas measures of body or organ weight had identified only 7 of the diets; 5 of these corresponded to the diets found in a previous analysis. We therefore conclude that measurements of weight alone are insufficient and should be combined with the results of histopathological examinations in studies on antinutritive properties of plants in the diet of meadow voles.
Diel feeding periodicity of two predatory stoneflies (Plecoptera)
Authors: Walde Sandra J. , Davies Ronald W.
Published: March 2009

Diel periodicity in feeding activity has not yet been established as a general pattern for predatory stoneflies. This study demonstrates by gut content analysis and behavioural observation that two predatory stoneflies, Kogotus nonus (Needham and Claassen) and Kogotus modestus (Banks) (Plecoptera: Perlodidae), do exhibit diel periodicity, but are not exclusively nocturnal feeders. Furthermore, the particular pattern of periodic feeding appears to depend on the prey type, as chironomids were consumed from evening through to morning, while the mayfly, Baetis, was infrequently captured during the night. Manipulation of light regime in the field and in the laboratory showed that periodic feeding was not a direct response to light regime. The observed diel feeding pattern may be due to a response to temperature regime coupled with diel changes in prey behaviour.
The evolution of sexual dimorphism in the skink Eumeces laticeps: an example of sexual selection
Authors: Vitt Laurie J. , Cooper Jr. William E.
Published: March 2009

Adults of the skink Eumeces laticeps are sexually dimorphic in coloration, body size, head size, and relative head size. Males have larger heads at a given body size than females and the divergence in relative head size is coincident with the size at which sexual maturity is reached. Although there were no differences between sexes in tail loss frequencies, there were substantial differences in frequencies of body and head scars, a consequence of aggressive male–male interactions. Prey size was correlated with body and head size and males tended to eat larger prey items than females. However, both sexes are capable of eating prey much larger than the mean or maximum size of prey found in stomachs, suggesting that resource partitioning is a consequence of sexual size differences rather than a cause. The heads of males at a given body size increase during the breeding season, and a combination of head and body size apparently determines the outcome of intrasexual aggressive encounters. Moreover, small males were never observed with females during the breeding season, and those males observed "guarding" females were significantly larger than males observed in the absence of females. We conclude that sexual selection accounts for many of the differences in morphological traits between sexes of E. laticeps.
Stimulation of courtship displays in ring-billed gulls using playback of vocalizations
Authors: Fetterolf Peter M. , Dunham David W.
Published: March 2009

The playback of vocalizations associated with visual courtship displays of ring-billed gulls (Larus delawarensis) stimulated courtship behaviors. Males and females responded more strongly to playback calls of their own sex than to playback calls of the opposite sex. This sex-specific response may be related to the reduction of interference with copulation.
Responses to rapid temperature change in the Pacific lamprey (Lampetra tridentata)
Authors: Lemons Daniel E. , Crawshaw Larry I.
Published: March 2009

Some aspects of the thermal biology of the Pacific lamprey (Lampetra tridentata) were studied by making rapid changes in the ambient water temperature (Ta). Calorimetric studies were conducted to determine the rate of ensuing changes in mean body temperature [Formula: see text] and various deep body temperatures. Cardiovascular–respiratory alterations were evaluated in an experimental flow-through apparatus in which Ta could be rapidly shifted while changes in ventilation frequency (fV) and heart rate (fH) were recorded. Immediately following a step increase in Ta, the change in [Formula: see text] of a 0.21-kg lamprey was 33% complete in 33 s and 67% complete in 127 s. Deep dorsal muscle temperature changed much more slowly, being 33% complete in 87 s and 67% complete in 225 s. During rapid shifts in Ta, fV and fH changed at a significantly greater rate than would be predicted taking into account the change in [Formula: see text] and the resultant Q10 effects on metabolism. This effect persisted when the [Formula: see text] of the water was held at 600 Torr (1 Torr = 133.322 Pa). A possible interpretation of the results is that lampreys, like other water-breathing vertebrates, sense alterations in peripheral temperature and utilize this information to alter the output of the ventilatory and cardiovascular systems in a way that anticipates some of the metabolic effects of temperature.
Magnesium and calcium metabolism during molting in the freshwater prawn Macrobrachium rosenbergii
Authors: Fieber Lynne A. , Lutz Peter L.
Published: March 2009

Magnesium and calcium concentrations were recorded in the extracellular fluid, exoskeleton, and hepatopancreas of the Malaysian freshwater prawn Macrobrachium rosenbergii throughout the molting cycle. Sixty male prawns distributed among five molt states (intermolt (C), early premolt [Formula: see text], late premolt [Formula: see text], early postmolt (A), and late postmolt (B)) were dissected for analysis of body components. Magnesium concentration in the whole bodies of 14 prawns was established. Magnesium levels in the extracellular fluid, exoskeleton, and hepatopancreas increased over the intermolt concentrations during premolt stages [Formula: see text], from 0.42 to 1.56 mmol∙L−1 in the extracellular fluid, from 0.09 to 0.47 mmol∙g dry weight−1 in the exoskeleton, and from 0.015 to 0.094 mmol∙g dry weight−1 in the hepatopancreas. A sevenfold increase in whole body magnesium, from 0.108 to 0.770 mmol∙g dry weight−1, occurred during premolt. During postmolt, magnesium concentrations of the whole body and of all body compartments measured declined steadily. Calcium levels in extracellular fluid, exoskeleton, and hepatopancreas also increased during premolt. In early postmolt stage A, however, exoskeleton calcium increased significantly while extracellular fluid and hepatopancreas calcium concentrations were depleted and during late postmolt stage B began to rise toward intermolt (C) levels. Whereas calcium changes during molting reflect the importance of calcium in the exoskeleton, changes in magnesium concentration are independent of any role this ion has in skeletal hardening.
Ventilatory response to venous CO2 loading by gut ventilation in ducks
Authors: Jones David R. , Milsom William K. , Butler Patrick J.
Published: March 2009

Venous CO2 loading was achieved in unanesthetized, spontaneously breathing white Pekin ducks by gut-ventilation to load CO2 across the intestinal circulation. Gut ventilation with air had no effect on breathing, while venous CO2 loading resulted in an increase in minute ventilation [Formula: see text]. Ventilation sensitivity [Formula: see text] when expressed as a percentage of [Formula: see text] obtained either without or during gut ventilation with air (15%∙mmHg−1; 1 mmHg = 133.322 Pa) was within the range of values previously recorded in birds by investigators using other techniques. An isocapnic hyperpnea, as observed in some other studies, was never seen using gut loading of CO2. These experiments have shown the efficacy of loading CO2 across the gut wall in ducks and this technique should prove useful in resolving the roles of the various CO2-sensitive receptor groups in increasing [Formula: see text] in response to CO2 loads.
Microhabitat shifts and substrate selection by the psammophilous predator Pseudiron centralis McDunnough (Ephemeroptera: Heptageniidae)
Authors: Soluk Daniel A. , Clifford Hugh F.
Published: March 2009

The predaceous mayfly Pseudiron centralis McDunnough exhibited shifts in its association with different types of sandy substrate during larval development: stage I larvae were associated with marginal sands; stage II larvae exhibited no association; and stage III and IV larvae were associated with the substrate of the main-stream channel of the river, where sand is formed into active dunes (shifting sand). Ability to occupy areas of shifting sand is size related, probably because small larvae cannot cope with the physical stresses of these areas. Experiments indicate that stage III larvae avoid gravel, but do not differentiate between sand and silt. Shifting sands are hypothesized to be favourable environments for larger larvae because of greater accessibility of chironomid prey or the absence of potential predators in these areas. Larval spacing behavior is unlikely to affect patterns of larval distribution or density on the riverbed.
Comparative population ecology of Peromyscus leucopus and Peromyscus maniculatus
Authors: Wolff Jerry O.
Published: March 2009

The reproductive biology and population structure of Peromyscus leucopus and P. maniculatus were studied from 1981 to 1983 to determine if differences in demographic features were sufficient to explain the relative frequencies of the two species. A total of 444 P. leucopus and 244 P. maniculatus were caught 3912 times. The population density of P. leucopus declined from a high of 38 animals/ha to a low of 6 animals/ha from 1981 to 1983, and P. maniculatus declined from 19 to 2 animals/ha over the same time period. The reproductive season averaged 197 days for P. leucopus and 204 days for P. maniculatus and was bimodal, with peak activity in April–June and September–October. Litter sizes averaged 3.5 for P. leucopus and 3.4 for P. maniculatus. Two-week survival rates varied between ages and sexes, but ranged from 0.75 to 0.91 for both species. Immigration occurred throughout the year in both species but was most pronounced during the breeding seasons. Sixty-three percent of adult male and 47% of adult female immigrants were reproductively active. Fifty-six percent of P. leucopus and 55% of P. maniculatus attained residency. Mean length of residency varied among sexes, ages, and years for P. leucopus, but not for P. maniculatus. For P. leucopus, adults had longer residencies than juveniles at high densities, but juvenile females had longer residencies than adults or juvenile males at low densities. The lack of significant differences in the demographic features between the two species suggests that other factors are responsible for mediating their coexistence and maintaining a P. leucopus/P. maniculatus ratio of approximately 2:1.
Intestinal migration by Hymenolepis diminuta: 5-hydroxytryptamine, vagal stimulation, and intestinal secretions
Authors: Sukhdeo M. V. K. , Mettrick D. F.
Published: March 2009

The effects of 5-hydroxytryptamine (5-HT) (administered orally and by duodenal cannulation) and vagal stimulation on the anteriad migration of the adult Hymenolepis diminuta were examined. Surgical restriction of gastrointestinal secretions were done to determine if the effects of 5-HT and vagal stimulation were mediated via gastric or biliopancreatic secretions. Elevation of intraluminal concentrations of 5-HT by duodenal cannulation elicited worm migration via the action of the pancreatic secretions. Oral administration of 5-HT and vagal stimulation elicited migrational responses through additional pathways that did not involve the biliary–pancreatic secretions. 5-HT does not appear to have a direct effect on worm migratory behaviour.
Carbohydrate contents of goose forages from estuaries of James and Hudson bays
Authors: Jones Robert L. , Walgenbach Richard P. , Hanson Harold C.
Published: March 2009

Aerial portions of sedges and grasses collected in September had an average of 9.22% total nonstructural carbohydrate. About 44% of the total nonstructural carbohydrate was simple sugars and a large part of the difference was short-chain polysaccharides. Except in the one root sampled, starch was not an important component.
Oogenesis and spermatogenesis in Nephelopsis obscura and Erpobdella punctata (Hirudinoidea: Erpobdellidae) with comments on their life cycles
Authors: Singhal R. N. , Davies Ronald W. , Baird D. J.
Published: March 2009

Oogenesis and spermatogenesis in Nephelopsis obscura and Erpobdella punctata from Stephenson's Pond, Alberta, were examined during the reproductive season (May to October). In N. obscura, two cycles of oogenesis and spermatogenesis were recorded, the first in June and the second in October; however, it could not be unequivocally demonstrated that N. obscura is iteroparous, although the potential for this exists. In E. punctata, protandry occurred with one complete annual cycle of oogenesis and spermatogenesis. No evidence for iteroparity was found. The development of a clitellum was found to be an unreliable indicator of sexual maturity in both species.
Field manipulations of fox and gray squirrel populations: how important is interspecific competition?
Authors: Brown Bruce W. , Batzli George O.
Published: March 2009

The role of competition in free-living populations of tree squirrels was evaluated in two field experiments. (i) Numbers of adult female fox squirrels (Sciurus niger) were manipulated and the response of gray squirrels (Sciurus carolinensis) was monitored. (ii) Supplemental feeding with native mast was used to determine if food was limiting for squirrel populations in east-central Illinois. Although sample sizes were small, a trend towards increased survival and reproduction in supplemented woodlots lent support to the idea that food availability limits squirrel densities during some winters. The manipulation of adult female fox squirrels did not indicate that densities of either fox or gray squirrels could be explained simply by competition. Some dispersion patterns on the larger plots were consistent with competition, but other explanations could not be completely ruled out.
Oogenesis in a North American population of Aedes (Finlaya) togoi (Theobald) (Diptera: Culicidae)
Authors: McGinnis Kathryn M. , Brust Reinhart A.
Published: March 2009

The expression of autogeny in Aedes togoi and its timing are highly variable. Autogenous females, fed 10% sucrose and maintained at 24 °C with a photoperiod of 17.5 h light: 6.5 h dark, developed mature eggs between 5 and 30 days after eclosion. The percent autogeny in a population from Vancouver, B.C., collected as larvae from the field (P1 generation) was 42% ([Formula: see text] eggs/female); the percent autogeny in the laboratory F2 generation, unselected for autogeny, was 40% ([Formula: see text] eggs/female). In the laboratory colony, the process of maturing follicles to the egg stage was frequently delayed. Some females (8%) had mature oocytes on day 5, while 20, 27, and 44% of the female population had mature oocytes on days 6, 8, and 15, respectively. The presence of mature oocytes does not inhibit blood feeding: 17–26% of the females containing mature oocytes took blood, and embarked on a new round of oogenesis. The ovaries of these females contained two separate cohorts of primary follicles, viz., mature oocytes developed autogenously and oocytes developing as a result of the blood meal. Most of the autogenous females with mature oocytes (57–83%) refused blood. This indicates that the presence of mature follicles is a deterrent to feeding and probably to host-seeking. Mating had no effect on the proportion of females that was autogenous.
Mating between anadromous and nonanadromous Atlantic salmon, Salmo salar
Authors: Hutchings J. A. , Myers R. A.
Published: March 2009

Mating experiments were conducted to determine whether behavioural isolating mechanisms exist that would prevent interbreeding between anadromous and nonanadromous Atlantic salmon, Salmo salar. Males of both forms attempted to stimulate females of the other form to spawn and females responded by digging redds, spawning, and covering redds. Viable eggs were produced in both cases. These forms probably represent within-population phenotypic variation where they co-occur. Interbreeding can be expected if anadromous salmon are introduced into areas formerly occupied only by the nonanadromous form.
Size, sexual size dimorphism, and their measurement in Great Horned Owls in Alberta
Authors: McGillivray W. Bruce
Published: March 2009

The degree of reversed size dimorphism between male and female Great Horned Owls in Alberta was examined by measuring 18 skeletal and 7 external characters on museum specimens. Females are significantly larger than males on all characters except skull width, which is larger in males. The degree of sexual size dimorphism is highest for flight characters and weight and weaker for skull, body core, and lower limb elements. High variances associated with external characters make the use of Storer's dimorphism index an unreliable measure of between-sex differences. External characters show weak intercharacter correlations and are poorly correlated with size as defined by first principal component scores obtained from skeletal characters. Despite significant differences between an ideal size axis and eigenvectors of both correlation and covariance matrices, the three are shown to be equivalent in estimating size. Inequality among character variances bias the interpretation of covariance-based principal component analyses supporting the use of correlation matrices to determine patterns of shared variation. The high degree of intercharacter differences in sexual size dimorphism indicate that single characters provide poor estimates of size.
A new species of root-lesion nematode (Pratylenchidae: Nematoda) in Canada with a scanning electron microscope study of its head morphology
Authors: Anderson R. V. , Townshend J. L.
Published: March 2009

Pratylenchus sensillatus, a new monosexual species of root-lesion nematode in Canada is described and illustrated. The primary distinguishing characters are a low, rounded, offset head with three annules, a body length of 621 ± 0.39 μm, b value of 7.1–8.3 (7.8 ± 0.32), stylet length of 15–17 (15.6) μm, V value of 77–81 (79), a vulva–anus length 3.9 ± 0.5 times that of the tail length, absence of afunctional spermatotheca, and a subcylindrical tail with a broadly rounded, smooth terminus. Characteristic of the first head annule are wedge-shaped submedian sectors of the oral plate and the first finding of eight cuticular pits identifiable with cephalic and outer labial sensilla.
Studies on Chilodonella cyprini and C. hexasticha (Protozoa, Ciliata) by scanning electron microscopy
Authors: Wiles M. , Cone D. K. , Odense P. H.
Published: March 2009

Specimens of the kinetophragminophorid ciliates Chilodonella cyprini (Moroff, 1902) from goldfish (Carassius auratus) in Nova Scotia and Chilodonella hexasticha (Kiernik, 1909) from channel catfish (Ictalurus punctatus) in Arkansas were examined by scanning electron microscopy. They are round to foliate, ventrally flattened protozoa well suited for adherence to, and movement over, a flat host surface. Organelles including ventral ciliary rows, dorsal cilia, excretory pores, and a prominent cytopharynx are described. Dorsal surfaces of both species have a distinct reticulate pattern which represents a modification of the pellicle. Ventrolateral margins of C. cyprini contain rows of short cuticular proturberances not seen in C. hexasticha. Our specimens of the two species were distinguished by their total ventral ciliary row number (12–14 in C. hexasticha, 21 in C. cyprini). General morphology as revealed by scanning electron microscopy is compared with previous light microscopical observations. The taxonomic separation of the two species, C. cyprini and C. hexasticha, is confirmed.
Comparative ecology of Gerris remigis (Hemiptera: Gerridae) in two habitats: a paradox of habitat choice
Authors: Fairbairn D. J.
Published: March 2009

This study compares the population ecology of Gerris remigis (Hemiptera: Gerridae) in two habitats: a cool mountain stream, representing the characteristic habitat of this species, and the atypical habitat of a small, warm pond. Neither habitat supported breeding populations of any other gerrid species. The populations on the two sites were found to differ significantly with respect to population dynamics, dispersal, phenology, and wing dimorphism. Overall, the population on the pond was more productive than that on the stream, indicating that G. remigis can be highly successful in a warm, lentic habitat, in the absence of competing species. However, in spite of this success, adult G. remigis actively avoided the lentic site. Thus habitat choice in this species cannot be mediated solely by interspecific competition. Comparisons of the two sites suggest that current, temperature, and (or) shelter from direct sunlight and wind may act as proximate cues for habitat choice in this species. The striking differences between the two study populations are also evidence of a very high degree of phenotypic plasticity, which allows G. remigis to respond to differences in habitat characteristics on a very fine scale.
Life history and production of Goerita semata Ross (Trichoptera: Limnephilidae) in the southern Appalachian Mountains
Authors: Huryn Alexander D. , Wallace J. Bruce
Published: March 2009

In western North Carolina, populations of Goerita semata are restricted to moss- or liverwort-covered rock faces located in small, heavily shaded high-elevation streams. The larval developmental period was completed in about 655 days with two distinct cohorts being present at any time. Growth was slow, averaging only 0.71% ash-free dry mass per day, with the highest growth rate of 1.52% per day measured for fifth instar larvae between March and April. Weight losses occurred in overwintering larvae. In spite of low growth rates, relatively high production (including silk expenditure) was maintained by high larval densities (mean = 288∙m−2). Production in the rock-face habitat was 237.66 mg ash-free dry mass∙m−2∙year−1 or 47.53 mg ash-free dry mass∙m−2∙year−1 when weighted by areal proportion of rock-face substrate for the entire stream. Most growth occurred during the spring when fifth instar larvae accrued > 50% of the definitive larval weight. This period of enhanced growth was correlated with increases in water temperature and in diatom consumption by the larvae. During the spring, diatoms composed about 64% of the foregut contents. In contrast, amorphous detritus constituted about 91, 65, and 86% of the gut contents during the fall, winter, and summer, respectively. Diatom consumption was estimated to be responsible for 58% of the annual production.
The significance of the Southeast Shoal of the Grand Bank to humpback whales and other cetacean species
Authors: Whitehead Hal , Glass Carolyn
Published: March 2009

During June and July of 1982 and 1983 studies were made of the humpback whales on the Southeast Shoal of the Grand Bank of Newfoundland from a 13-m ketch. The humpbacks were found to concentrate on the central part of the shoal where surface and deep water temperatures were warmest and depths were shallowest, over concentrations of prey producing strong depth sounder traces. These traces were almost certainly made by spawning capelin. The humpbacks and prey traces dispersed as the season progressed. Other large whale species were much less numerous than the humpbacks, of which about 900 were estimated to use the shoal in 1982 and 1983. The Southeast Shoal humpbacks are a reasonably discrete segment of the Newfoundland–Labrador feeding stock, which winter in the West Indies, with the Southeast Shoal animals showing a particular preference for the waters off Puerto Rico. In 1982, individual whales were found to be generally moving slowly northwest over the shoal. Apart from forming very large coordinated groupings early in the studies, when the prey was most concentrated, the feeding and grouping behaviour of the humpbacks was similar to that in the inshore waters off Newfoundland.
Excystation of Isospora brachyrhynchi Cawthorn and Wobeser, 1985 in vitro
Authors: Stockdale P. H. G. , Sheard Anne , Cawthorn R. J.
Published: March 2009

Oocysts of Isospora brachyrhynchi Cawthorn and Wobeser, 1985 were recovered from feces of experimentally infected juvenile crows (Corvus brachyrhynchus) and stored for up to 12 months in a 2.5% (w/v) solution of potassium dichromate at 4 °C. Sporocysts were released from the oocysts by grinding in a homogenizer. Various bile salts, taurocholic acid, pooled chicken bile, sodium glycocholate, and sodium taurodeoxycholate were used in conjunction with trypsin as media to excyst sporozoites of I. brachyrhynchi. These media were tested at different temperatures and on oocysts stored for varying lengths of time. The most effective excystation (94%) was seen in oocysts that had been stored for 1 month and were incubated with 5.0% sodium taurodeoxycholate and 0.25% trypsin at 41 °C for 60 min. Varying degrees of excystation were observed using different bile salts at different temperatures on oocysts stored for up to 12 months.
Behavioural responses of lynx to declining snowshoe hare abundance
Authors: Ward Richard M. P. , Krebs Charles J.
Published: March 2009

The behavioural responses of lynx (Lynx canadensis) to declines in snowshoe hare (Lepus americanus) abundance were examined in the southwestern Yukon. Between April 1982 and June 1984, 11 lynx were radio tagged and monitored in and near the Kluane Game Sanctuary. Lynx home range size increased from 13.2 to 39.2 km2 concurrent with a decline in snowshoe hare abundance from 14.7 to 0.2 hares/ha. Below about 0.5 hares/ha, several lynx abandoned their home ranges and became nomadic, although they remained within the general study area. Lynx concentrated their foraging efforts in areas of relatively high snowshoe hare abundance and abandoned these areas after hares declined. Straight-line daily travel distance remained constant at 2.2−2.7 km/day above 1.0 hare/ha. Below 1.0 hares/ha, straight-line daily travel distances increased rapidly, reaching 5.5 km/day at 0.2 hares/ha. Three of seven radio-tagged lynx dispersed 250 km or more from the study area during the 1982 period of rapid hare decline. No similar long-distance emigrations were recorded after hare densities stabilized at less than 1.0 hares/ha. Trapping mortality was responsible for the loss of seven of nine radio-tagged lynx that travelled outside the game sanctuary. One lynx probably starved during the winter or spring of 1984. The high rate of trapping mortality outside the game sanctuary suggests that refugia in wilderness areas are important in maintaining lynx populations during periods of low recruitment.
The relative significance of body surface and cloacal respiration in Psolus fabricii (Holothuroidea: Dendrochirotida)
Authors: Hopcroft Russell R. , Ward D. Bruce , Roff John C.
Published: March 2009

Oxygen consumption at 10 °C was measured for Psolus fabricii, in whole animals and in specimens with the cloaca blocked to prevent use of the respiratory trees. In both sets of experiments, oxygen consumption was exponentially related to body size, but larger animals exhibited a significantly greater proportion of oxygen exchange by cloacal respiration. An animal of 80 g wet weight achieves 75% of its respiratory needs by actively pumping water through the cloaca, whereas body surface respiration alone is calculated to be adequate for a 1.9-g animal. It appears that because of their success in shallow areas of dynamic water motion, adult Psolus depend less than other holothurians on body surface respiration.
Histological observations on precystic merogony and metrocyte formation of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in varying lemmings, Dicrostonyx richardsoni
Authors: Cawthorn Richard J. , Brooks Ronald J.
Published: March 2009

This study was designed to elucidate the early endogenous development of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in varying lemmings, Dicrostonyx richardsoni. After determining the dose–response effects of sporocysts of S. rauschorum on lemmings (doses greater than 500 sporocysts were lethal during hepatic merogony), sporocysts were administered to additional lemmings that were killed beginning 1 day postinoculation (DPI) and continuing to 15.0 DPI. Merogony of S. rauschorum occurs in hepatocytes 4 – 6 DPI; merozoites were also found in leucocytes 5 – 6 DPI in liver impression smears. Cyst formation began 9.0 DPI in striated muscle (rarely in cardiac muscle) and only metrocytes were present to 15.0 DPI. Overall, S. rauschorum has only one precystic generation of merogony, in hepatocytes, and then rapidly forms cysts containing metrocytes in striated musculature.
Ultrastructure of the cysts of Sarcocystis tarandi from skeletal muscle of reindeer (Rangifer tarandus tarandus)
Authors: Gjerde Bjørn
Published: March 2009

Cysts of Sarcocystis tarandi from Rangifer tarandus tarandus were examined by transmission electron microscopy. The cysts were located within skeletal muscle cells and were limited by a unit membrane (the cyst membrane). The surface of the cyst was covered with densely packed, erect, villiform processes measuring 10.4 μm in length and 2.5 μm in diameter. The processes contained numerous longitudinally oriented microtubules. The cyst membrane was reinforced by an underlying 20–65 nm thick layer of electron-dense material, except at numerous points between the bases of the protrusions where it formed vesiclelike invaginations. Cyst ground substance formed a layer at the periphery of the cyst, filled the core of the projections, and formed septa that divided the cyst into many compartments. The compartments contained either cystozoites or metrocytes. The metrocytes possessed one or a few large dense bodies containing crystalline inclusions. The cystozoites multiplied by endodyogeny.
Trophozoite morphology and development site of two species of Myxobolus (Myxozoa) parasitizing Catostomus commersoni and Notemigonus crysoleucas in Atlantic Canada
Authors: Cone D. K. , Wiles M.
Published: March 2009

This study compares the morphology and development site of trophozoites of two gill parasitic species of Myxobolus, one from Catostomus commersoni in Nova Scotia and one from Notemigonus crysoleucas in New Brunswick. Trophozoites of the former are embedded in tissue lying between the bases of two adjacent primary lamellae. They are round, saclike structures full of mature spores. Developmental phases aggregate near the peripheral inner surface. The trophozoite's outer edge is bound firmly to a mitotically active, single-celled layer that is identified as a modified capillary wall. Beyond this is a host capsule consisting of loose connective tissue, eosinophilic granulocytes, and epithelial cells. Trophozoites of the species of Myxobolus from N. crysoleucas develop in the distal half of a primary lamella. They are irregularly shaped, internally compartmentalized sacs. Each minute compartment contains a single spore. Developmental phases are distributed throughout the trophozoite's interior and their growth within a germinal matrix forms the compartments. Remnants of secondary lamellae pass through the trophozoite's interior and, although the original outer epithelium is absent, the remaining blood vessels still function in blood-cell transport. The trophozoite is surrounded by a loose connective tissue capsule. The study also compares the overall form of the two types of trophozoites.
The azurocyte: a new kind of leukocyte from wild voles (Microtus)
Authors: Mihok Steve , Descôteaux Jean-Paul , Lawton Todd , Lobreau Anya , Schwartz Bill
Published: March 2009

We have identified a new mammalian leukocyte from voles (Cricetidae, Microtus). This "azurocyte" is a large mononuclear cell with numerous cytoplasmic inclusions that stain purple with azure dyes. The cell resembles a young lymphocyte with numerous mitochondria, a prominent Golgi complex, and modest amounts of rough endoplasmic reticulum. The inclusions are homogeneous, membrane-bound, electron-dense bodies that contain a highly acidic, sulphated glycosaminoglycan, glycoprotein, nonspecific esterase, β-glucuronidase, and an aminopeptidase. Azurocytes are common in adult voles, particularly pregnant females, and can be induced artificially with progesterone. In humans (large granular lymphocyte) and in guinea pigs (Kurloff cell), morphologically distinct cells with azurophilic inclusions have been associated with natural killer activity. The vole azurocyte may therefore be a similar leukocyte with special functions during pregnancy.
Morphology and digestive efficiency of red foxes (Vulpes vulpes) and grey foxes (Urocyon cinereoargenteus) in relation to diet
Authors: Jaslow Carolyn Renzulli
Published: March 2009

Measurements of the skull and dentition, and digestive efficiency of red foxes (Vulpes vulpes) and grey foxes (Urocyon cinereoargenteus) were compared to determine whether differences in morphology and digestive ability could be associated with dietary preference. The longer jaws of the more carnivorous red fox increase the resistance moment arm when biting at the canines and carnassials, but greater size and mechanical leverage of the masticatory muscles in this species compensate for this, enabling the red fox to bite with forces that should be comparable to or exceed those of the grey fox. The relatively shorter masticatory moment arms of the more omnivorous–insectivorous grey fox should increase bite speed. Both fox species digested mice with equal efficiency, but the more omnivorous grey foxes had higher digestive efficiencies than red foxes when fed a diet of fruit. These morphological and physiological differences observed between sympatric red foxes and grey foxes may allow each species to exploit different foods more effectively.
Breeding ecology, nest characteristics, and nest-site selection of stream- and lake-dwelling rock bass, Ambloplites rupestris (Rafinesque)
Authors: Noltie Douglas B. , Keenleyside Miles H. A.
Published: March 2009

This study examines the breeding ecology, nests, and nest-site selection of stream-dwelling rock bass, Ambloplites rupestris (Rafinesque), populating the Middle Thames River near London, Ontario. Breeding in this stream began earlier, at lower temperatures, and continued longer than in other documented lake-breeding populations. These responses were related to flooding which repeatedly thwarted breeding attempts. Nesting and spawning continued asynchronously throughout the seasons, increasing breeding opportunities. Older, larger males spawned earliest in the season, allowing them increased renesting opportunities. The duration of each stage in nesting and brood development was documented. Nests were generally larger than those of other rock bass populations. Male size and nest size were positively related. Nests were elliptical rather than circular as in lakes, reflecting the influence of water flow. Males demonstrated nest-site selection: individual nest sites were allocated nonrandomly with respect to depth, reflecting the availability of appropriate nesting substrates, and the majority of nests were constructed downstream from obstructions to current. Many of these features of rock bass reproduction can be interpreted as being responses to the relatively variable and rigorous environment of the stream habitat as compared with lakes.
Faunal zones in the northwestern Atlantic based on polychaete distribution
Authors: Pocklington P. , Tremblay M. J.
Published: March 2009

Polychaete presence/absence data (303 species at 50 locations) were used to identify faunal zones within the coastal region of the northwestern Atlantic between Hudson Strait and Cape Hatteras. Labrador, Acadian, and Virginian faunal zones were distinguished using cluster analysis. It was found that different depths at the same latitude belong to different faunal zones. A comparison with previous zoogeographic classifications is made, and strong parallels were found to exist between polychaete distribution and that of other groups of invertebrates.
Sex ratios of hatchling Mourning Doves
Authors: Edmunds Suzanne R. , Ankney C. Davison
Published: March 2009

The sex of 306 Mourning Dove (Zenaida macroura) chicks from 153 two-egg clutches laid during March–August 1984 was determined by gonadal inspection. Sex of offspring was unrelated to egg sequence over the entire breeding season. There was, however, a seasonal effect on the sex versus egg sequence pattern, particularly in broods with both sexes: during the middle of the breeding season males predominated in first eggs and females in second eggs but this pattern was reversed late in the season. All other comparisons, i.e., overall sex ratio, seasonal changes in sex ratio, binomial distribution of family types, and the relation between egg size and offspring sex, were nonsignificant.
Male-biased adult sex ratios in a red squirrel population
Authors: Hurly T. Andrew
Published: March 2009

A 3-year study of a red squirrel population revealed that the adult sex ratio was biased towards males. There is no evidence that the skewed sex ratio was prejudiced by sampling biases due to sexual differences in mobility, observability, trappability, or habitat use. The tertiary juvenile sex ratio was even and therefore not the cause of the biased adult sex ratio. The data suggest that the skewed sex ratio may be the result of differential mortality. This is consistent with other reports of higher female than male mortality in red squirrels.
Dental ontogeny of harp seals, Phoca groenlandica
Authors: Stewart R. E. A. , Stewart B. E.
Published: March 2009

Harp seal fetuses and neonates were examined to determine the development, resorption, and eruption characteristics of deciduous and permanent dentition. Early September fetuses had recently formed, deciduous teeth only. By early December the deciduous dentition was robust and enameled. Permanent teeth were also present. In late December the roots of the deciduous teeth were being resorbed and the permanent dentition was larger and better developed. About 80% of the deciduous teeth were resorbed by birth in March. The rest were resorbed or shed after birth. The pattern of permanent tooth eruption was not correlated with pup age but the total number of teeth erupted increased significantly with increasing pup age, from 38% in newborns to 100% in weaned pups about 3 weeks old. The neonatal line formed at birth rather than at weaning or the onset of moult.
The relationship between nematodes of the genus Cosmocercoides Wilkie, 1930 (Nematoda: Cosmocercoidea) in toads (Bufo americanus) and slugs (Deroceras laeve)
Authors: Vanderburgh Daryl J. , Anderson R. C.
Published: March 2009

Nematodes of the genus Cosmocercoides Wilkie, 1930 from Bufo americanus and Deroceras laeve, generally considered to belong to the same species (Cosmocercoides dukae), were compared. Male worms from B. americanus had 20 or 21 rosette papillae per subventral row whereas males from D. laeve had 13 to 14. Worms from toads had numerous simple postanal papillae. Worms from slugs generally lacked such papillae. Worms from the two hosts differed morphometrically and were well separated by discriminant analysis after bias of worm length was removed by analysis of covariance. Differences in isoenzyme migration were detected using starch gel electrophoresis. In cross-transmission experiments, more toads became infected when exposed to larvae of worms from toads than when exposed to larvae of worms from slugs. More slugs became infected when exposed to larvae from slugs than when exposed to larvae from toads. Intensity of mature worms recovered was significantly (p < 0.05) greater (and patent infections developed) when transmission was from toad to toad or from slug to slug than when transmission was from toad to slug or from slug to toad. No patent infections were recorded from toads or slugs exposed to larvae from the unrelated host. The results indicate that worms in toads and slugs are not conspecific. Cosmocercoides variabilis (Harwood, 1930) Travassos, 1931 is resurrected as the name of the species occurring in B. americanus, Cosmoceroides dukae (Holl, 1928) Travassos, 1931 is retained as the name of the species occurring in D. laeve.
Biology and immature stages of Dichetophora obliterata, a snail-killing fly (Diptera: Sciomyzidae)
Authors: Vala Jean-Claude , Caillet Christine , Gasc Charles
Published: March 2009

We present descriptions of the egg, the three larval instars, and the puparium, and also some information on the biology of Dichetophora obliterata, a strictly terrestrial Sciomyzidae (Diptera). This life cycle is the first that has been published for a species in this genus. We provide information on the flight period of adults, the duration of preoviposition and all immature stages, and the larval feeding behavior. By all these characteristics, D. obliterata (palearctic) is placed in phenologic group IV of Berg et al. (Berg, C. O., Foote, B. A., Knutson, L. V., Barnes, J. K., Arnold, S. L., and Valley, K. 1982. Mem. Entomol. Soc. Wash. 10: 15–36).
Stygobromus quatsinensis, a new amphipod crustacean (Crangonyctidae) from caves on Vancouver Island, British Columbia, with remarks on zoogeographic relationships
Authors: Holsinger John R. , Shaw D. Patrick
Published: March 2009

Stygobromus quatsinensis, a new species of subterranean, freshwater amphipod crustacean, is described from caves on Vancouver Island, British Columbia, Canada. This is the 3rd stygobiont amphipod recorded from Canada and the 11th member of the genus Stygobromus to be found in localities north of the southern limits of Pleistocene glaciation. Stygobromus quatsinensis is a member of the hubbsi group, an assemblage of closely similar stygobiont species previously recorded from the central and western United States south of British Columbia. Two alternative hypotheses are proposed to explain the presence of S. quatsinensis on a glaciated island separated from the mainland by marine straits. One theory suggests that it evolved from putative ancestors that were present on the island before development of the Juan de Fuca Strait in the Eocene. The other suggests that it gained access to the island from the mainland through interstitial routes in coarse sediments of the Quadra Sand which infilled parts of the Georgia Strait in the late Pleistocene. Both theories assume that this species has survived glaciation in subglacial groundwater refugia.
Phylogenetic relationships and evolution in the genus Dissodactylus Smith, 1870 (Crustacea: Brachyura: Pinnotheridae)
Authors: Griffith Hugh
Published: March 2009

A cladogram indicating sister-group relationships within the pinnotherid crab genus Dissodactylus is constructed from analysis of 28 morphological characters. The outgroup method was used to determine character polarities. Parapinnixa and Sakaina are shown to be a monophyletic group, and are suggested to be the sister group of Dissodactylus. Within Dissodactylus, two mutually exclusive, monophyletic subgroups are found, one containing nine, the other four species. Both of these groups include Atlantic and Pacific representatives. Two Atlantic–Pacific species pairs are suggested to be sister species (D. mellitae–D. glasselli and D. primitivus–D. schmitti). Members of the group of nine species are inhabitants primarily of mellitid sand dollars, although one species, D. primitivus, is a symbiont of heart urchins (Spatangoida). Members of the group of four species are inhabitants of sea biscuits of the genus Clypeaster (Clypeasteridae). An evolutionary scenario is presented, which suggests that a free-living ancestor colonized mellitid sand dollars, and subsequent specializations led to the colonizations of the genus Clypeaster and genera of Spatangoida.
Population fluctuations in spruce grouse: what determines their numbers in spring?
Authors: Boag D. A. , Schroeder M. A.
Published: March 2009

The number of spruce grouse (Falcipennis (Canachites) franklinii) present in the spring population on a 247-ha block of pine-dominated habitat in southwestern Alberta was counted annually over a 21-year period. During the first 5 years of this study, the population increased steadily from 7.3 to 16.6 grouse/100 ha. Subsequently, for a period of 11 years, numbers were relatively stable at higher densities (19.0–29.1 grouse/100 ha). During the last 5-year period, the population declined to levels lower than at the onset of the study (16.6–4.9 grouse/100 ha). Year to year fluctuations in the size of this population were considered in the light of two hypotheses put forward to explain such fluctuations (spacing behaviour and breeding success). We concluded that both hypotheses were needed to explain our observations. During those years when spring population size fell below the mean number of grouse recorded over the 21-year period (17.8/100 ha), there was some evidence that breeding success in one year may have influenced population size the following spring but we found no evidence that spacing behaviour was important in limiting numbers under these conditions. On the other hand, when the size of the spring population was greater than the mean there was no evidence that breeding success influenced changes in population size the following spring, but there was evidence that spacing behaviour was limiting recruitment. The long-term change in population size appeared to be tied to the status of the fire sere inhabited: maturation of the forest (principally an increase in the height) was accompanied by a decline in population size.
The effects of experimental manipulation of resources on the behavior of two calopterygid damselflies that exhibit resource-defense polygyny
Authors: Alcock John
Published: March 2009

Male odonates offer many examples of resource-defense mating systems and provide opportunities to test the hypothesis that in such systems the amount of resources controlled by a male will determine his mating success. Experimental alterations in oviposition site resources contained in the territories of the calopterygid damselflies Calopteryx maculata and Hetaerina vulnerata yielded different results. Removal of all oviposition resource substrate from occupied territories of H. vulnerata did not cause males to abandon their sites, nor did it affect the probability that females would come to these areas to mate. In contrast, males of C. maculata whose territories had been stripped of floating plant material generally abandoned the area within 1 h. Females of this species were more strongly attracted to sites with the most oviposition resources and males fought more intensely for these territories. Because females and males of C. maculata can assess the amount of floating substrate in a territory, this information influences where individuals mate, which sites they defend, and the intensity with which they fight for a location. In H. vulnerata, however, females oviposit underwater into sunken plant material hidden beneath fast-moving water. Because resource assessment is more difficult in H. vulnerata, females do not secure information on the quantity of oviposition substrate in a male's territory prior to mating, and male mating tactics, therefore, differ substantially from those employed by C. maculata.