bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal acclimation in fish: conservative and labile properties of swimming muscle
Authors: Guderley Helga , Blier Pierre
Published: March 2009

Given the rapid thermal equilibration of most fish with their environment, thermal compensation of metabolic and contractile properties is essential for the maintenance of locomotory capacities over a wide range of temperatures. The response of fish swimming performance, contractile properties of isolated fibers, myosin ATPase activity, and metabolic systems for ATP generation to short- and long-term changes in temperature have received sufficient study to allow one to identify certain constrained and labile properties. Sustained swimming performance and its components generally have their optimal performance and lowest thermal sensitivity within the range of temperatures frequently encountered by the organism. These principles are particularly well established for isolated enzyme systems. Furthermore, swimming performance and most of its components demonstrate thermal compensation on the evolutionary time scale. Temperature acclimation also leads to compensatory responses which, while quite species-specific, consistently increase the capacity for sustained swimming at low temperatures. The position of the thermal optimum for locomotion in relation to the width of a species' tolerance limits aids in predicting the species' capacity for thermal compensation during acclimation. Goldfish (Carassius auratus) and common carp (Cyprinus carpio), which tolerate temperatures 25–30 °C below their optimum for locomotion, show thermal compensation in terms of contractile properties, myosin ATPase activity, the proportion of red fibers in their axial musculature, and the levels of aerobic enzymes in their musculature. By contrast, striped bass (Morone saxatilis) and chain pickerel (Esox niger), which have lower optimal temperatures for locomotion, only increase the proportion of red fibers and (or) the levels of aerobic enzymes with cold acclimation. Finally, lake whitefish (Coregonus clupeaformis), which have their optimal temperature for locomotion at 12 °C, show none of these responses. Given that when thermal compensation occurs, aerobic enzymes in red muscle generally increase, the capacity of red muscle to generate ATP seems more temperature sensitive than other metabolic or contractile properties. Whether this compensatory response serves to counteract the effect of temperature on diffusive exchange between mitochondria and the cytoplasm or its effect on the catalytic capacity of aerobic metabolism remains to be established.
Does social behavior drive vole cycles? An evaluation of competing models as they pertain to California voles
Authors: Heske Edward J. , Ostfeld Richard S. , Lidicker Jr. William Z.
Published: March 2009

The literature contains a number of verbal and mathematical models that assert that social behavior drives the multiannual density cycles characteristic of many vole species. Many of the assumptions about vole behavior on which the models are based remain unverified. In this paper we briefly review these models and their underlying assumptions. We then use natural history data on the social behavior of California voles (Microtus californicus) to critically examine the plausibility of these assumptions. We do not attempt to explain vole cycles, but only to evaluate models that rely strongly on social behavior as a critical component. Our results indicate that (i) critical assumptions of the behavioral polymorphism, social stress, and social breakdown hypotheses are not met; (ii) some assumptions of the kin selection hypothesis are met whereas others are not; and (iii) assumptions of the habitat patchiness – dispersal hypothesis are met. However, published models of dispersal and habitat patchiness must invoke additional factors, such as resource depletion or predation, before cycles result. We conclude that social behavior is unlikely to be a driving force in the generation of cycles in the California vole. We hope that our approach will stimulate further research specifically directed at assumptions of these models.
Paternal behavior by Peromyscus leucopus in enclosures
Authors: Xia Xuhua , Millar John S.
Published: March 2009

Male Peromyscus leucopus are known to exhibit well-developed paternal behavior in confined cages, but electrophoresis indicates promiscuity in this species. One explanation for this paradox is that the documented paternal behavioral patterns are laboratory artifacts. We made nocturnal observations of parental behavior in 14 families of P. leucopus in large enclosures and observed no paternal care. Males rarely entered the natal nest and when they did, remained in the nest for less than 2 min. Thus, we consider direct paternal care such as licking, retrieving, and huddling unlikely. We also failed to observe any indirect paternal investment such as nest building or food caching. The female in each of five pairs was very aggressive towards the male, continuously chasing him throughout most of the observation periods. Another three females actively prevented their mates from entering the natal nest. Paternal care probably does not contribute to the growth and survivorship of the young under natural conditions.
A review of the cave fauna of Canada, and the composition and ecology of the invertebrate fauna of caves and mines in Ontario
Authors: Peck Stewart B.
Published: March 2009

Caves and cave-inhabiting faunas of Canada are reviewed. Four species of troglobitic (cave-limited) crustaceans (Amphipoda and Isopoda) are known from Alberta and British Columbia, and one troglobitic mite from Alberta. A study of the subterranean fauna of Ontario involved investigating 35 caves and mines. Collections of 1274 invertebrate specimens contained 301 species in 5 phyla, with spiders and insects being most numerous. Diptera were the most abundant insects with 140 species, mainly in the families Culicidae, Mycetophilidae, and Tipulidae. The fauna is predominantly composed of trogloxenes, in the "parietal association." Few troglophiles and no troglobites were found. The fauna is most abundant in individuals and richest in species diversity within the first 10 m of the entrances, just inside the dark zone, and at 12–14 °C. The total "community" of terrestrial invertebrates does not show significant preferences in either caves or mines for precise locations on environmental gradients of light, temperature, or relative humidity. Faunal movements and changes occur on a daily and a seasonal basis. There is no clear difference between the faunas of "old" caves and those of "young" mines. The cave and mine faunas are generally scavengers or predators recruited from nearby forest litter and soil populations. None of the species were significantly outside their previously known distributional range.
Grasshopper (Insecta: Orthoptera: Acrididae) assemblages of tallgrass prairie: influences of fire frequency, topography, and vegetation
Authors: Evans Edward W.
Published: March 2009

Grasshopper assemblages were sampled by sweep net in native tallgrass prairie at Konza Prairie, Kansas, in 1982 – 1986 to assess the influences of fire, topography, and vegetation on local species composition. Species composition at 38 sites was analysed by ordination (detrended correspondence analysis). Frequency of fire and topographic location were reflected along the first two principal axes, respectively. Grass-feeding grasshoppers were more numerous than forb- and mixed-feeding grasshoppers throughout the prairie, but forb and mixed feeders became relatively more frequent as fire frequency decreased. Local species richness of grasshoppers was greater on sites burned infrequently than on sites burned annually or biennially, and on upland than on lowland sites. Local species richness was positively correlated with local plant species richness and diversity, reflecting in part that local relative abundance of forb-feeding grasshoppers was positively correlated with local relative abundance of forbs. Collectively these results are consistent in suggesting that through their effects on local plant communities, fire frequency and topography are major factors influencing the composition of local grasshopper assemblages in tallgrass prairie.
Egg size and shape, clutch dynamics, and reproductive effort in European tortoises
Authors: Hailey A. , Loumbourdis N. S.
Published: March 2009

Energetic aspects of female reproduction are described for the tortoises Testudo graeca, Testudo marginata, and Testudo hermanni (three populations of different body size) from northern Greece. Egg width increased with body size in some populations, but smaller individuals produced more elongate eggs, and egg weight was not related to body size. This method for overcoming the constraint of the width of the pelvic canal means that egg width is a poor measure of egg size. Clutch size, clutch mass, and annual egg production varied with body size between populations. Mean relative clutch mass ranged from 4 to 7%, and was highest in the three populations of T. hermanni. All populations laid two or three clutches per year, based on the total number of eggs and large follicles divided by clutch size. Multiple clutches reflect the morphological constraint of packing shelled eggs within the body, rather than energy accumulation during the nesting period. Material for reproduction was stored in growing follicles rather than fat bodies; follicles reached half of their final weight before the animals entered hibernation. Annual reproductive effort as a proportion of body energy content was about 15% in all populations. This is lower than in other reptiles, partly because the carapace accounts for over half of the total ash-free dry weight of the tortoise body.
The ventral adhesive disc of the clingfish Gobiesox maeandricus: integumental structure and adhesive mechanisms
Authors: Green David M. , Barber D. Louise
Published: March 2009

Light microscopy and scanning and transmission electron microscopy of the ventral adhesive disc of the northern clingfish, Gobiesox maeandricus, demonstrate that two distinct types of epidermis are present on the disc surface. Most of the disc is covered with cuboidal epithelium in which four cell types can be distinguished: acidophil cells, mucous cells, epithelial cells, and "alarm substance" cells. The surfaces of the epithelial cells feature whorled microridges typical of teleost epidermis. Near the margin of the disc, on the lateral fin rays, and in discrete raised patches inside the disc are papillae of stratified columnar epithelium. The surface cells of these papillae are microvillous and secrete a noncellular cuticle which is firmly anchored to the microvillous surface of the papillae. The cuticle is not adhesive. It contains keratin-like proteins but no mucins or mucoproteins are demonstrable histochemically. Connective tissue layers and muscle underlying the epidermis of the disc are arranged to provide structural integrity and shock absorption while allowing some flexibility to the disc and papillae. The adhesive force generated by the disc was demonstrated using a pressure transducer. Negative pressure decays over time and is periodically renewed by the fish. Thus suction is largely maintained passively and the disc's seal is subject to some leakage. The fish can also actively apply suction pressure when agitated but fatigues and cannot sustain high negative pressures for long. The epidermal papillae, coupled with the fish's ability to flex the disc, represent an additional gripping mechanism for irregular surfaces. The papillary surface cuticle apparently acts as an abrasion-resistant, frictional surface.
Observations on spermatogenesis, sperm phenotype, and fertility in white-tailed × mule deer hybrids and a yak × cow hybrid
Authors: Wishart William D. , Hrudka Francis , Schmutz Sheila M. , Flood Peter F.
Published: March 2009

Fertility, spermatogenesis, and sperm phenotype were investigated in three hybrid deer (Odocoileus virginianus dacotensis × Odocoileus hemionus hemionus) and a yak × domestic cow hybrid (Bos mutus (grunniens) × Bos primigenius (taurus)) using histological techniques. All of the hybrids studied were infertile but varied in the degree of testicular differentiation, spermatogenic activity, and sperm production. The hybrid yak was the least developed and the white-tailed deer × F1 hybrid was the most advanced. F1 backcrossing improved spermatogenesis, output, and morphology of sperm, but not the fertility of the donor, indicating that normal sperm morphology alone does not assure fertility. Two deer hybrids that produced sperm differed in sperm phenotype from each other and from the parental species. Interaction of a Y chromosome from one species and autosomal sex-determining genes from the other species is suggested as a possible explanation of sterility in male hybrids.
Developmental stage of offspring and brood defense in smallmouth bass (Micropterus dolomieui)
Authors: Ridgway Mark S.
Published: March 2009

Life history models of parental care predict that parents should adjust their level of defense to reflect the increasing value of current offspring relative to their own expected future reproduction. This field study examined the effects of the developmental stage of offspring on patterns of brood defense in parental male smallmouth bass (Micropterus dolomieui). Conspecific models of equal length (±1 cm) were used to elicit two defense behaviours: bite and jaw display (a threat display). Parental defense increased as offspring progressed from egg to wriggler (hatched embryos) stages, and peaked before fry "swim-up" from the nest. Parental defense decreased after swim-up. This pattern of brood defense conforms with the life history model of parental care through a brood cycle. Four alternative hypotheses to the life history model are discussed (habituation to the model, nest conspicuousness, food value of offspring, and repeated success in nest defense); each is inadequate in accounting for the observed patterns in defense over the brood cycle.
Impact du labour–hersage sur la communauté lombricienne, en plantation récente de feuillus
Authors: Garceau Carole , Coderre Daniel , Popovich Stevo
Published: March 2009

Five species of earthworms have been identified in a clay soil at the site of a recent plantation of deciduous trees: Lumbricus terrestris, Lumbricus festivus, Lumbricus castaneus, Aporrectodea turgida, and Eisenia rosea. The effects of ploughing and harrowing on earthworms in such an environment were evaluated using an experimental procedure with three random plots and two sampling periods. Conditions, particularly humidity and temperature, are modified in the top 10 cm of the ploughed and harrowed soil. These effects, combined with the physical impact of the machinery, result in a reduction of the richness, diversity, abundance, and biomass of the earthworm community. The age structure of the community is also affected.[Journal translation]
Estimating diet composition from scat analysis in otariid seals (Otariidae): is it reliable?
Authors: Dellinger T. , Trillmich F.
Published: March 2009

Analysis of teleost sagittal otoliths contained in scats has been widely used to determine the diet of seals. This method is based on the assumption that relative frequencies of otoliths in scats faithfully reflect those offish in the diet. This assumption has rarely been tested experimentally. We compared the ratios of herring (Clupea harengus) to sprat (Sprattus sprattus) otoliths in faeces (output) of captive California sea lions (Zalophus californianus) and South American fur seals (Arctocephalus australis) with the ratios at feeding (input). Sea lions and fur seals showed no consistent differences in recovery rates and partial digestion of otoliths. Output ratios deviated only slightly from input ratios, the smaller sprat otoliths being underrepresented in the output by 8%. Only about 40% of the otoliths fed to the seals were found in the scats. For both species partial digestion of otoliths led to a 16% underestimation of fish length and a 35% underestimation of fish mass.
Additional records on intersexuality in the isopod Mesidotea sibirica (Birula, 1896)
Authors: Korczynski R. E.
Published: March 2009

Intersexes of the isopod Mesidotea sibirica (Birula, 1896) from Pauline Cove, Herschel Island, Yukon Territory, are described. The specimens are all masculinized females. The number and development of male characters is greater than was reported in the first description of intersexuality for the species. Intersexes of M. sibirica have been reported only from Pauline Cove.
Differences in flight and heart muscle mass among geese, dabbling ducks, and diving ducks relative to habitat use
Authors: Bethke R. W. , Thomas V. G.
Published: March 2009

Geese, dabbling ducks, and diving ducks differ in their ability to take off vertically when initiating flight. For three species of goose (N = 127), five species of dabbling ducks (N = 89), and eight species of diving ducks (N = 128), the masses of pectoralis, supracoracoideus, and heart muscles, and two indices of wing form (wing loading and aspect ratio) were measured. Differences in take-off ability among the groups were associated with differences in the mass, i.e., the potential power output, of the flight and heart muscles, and in wing form. Dabbling ducks had the greatest relative mass of flight muscles (p < 0.0001), lowest wing loading, and highest aspect ratio, and elevate almost vertically from the water's surface when taking off. Conversely, diving ducks had the smallest flight muscles, highest wing loading, and smallest aspect ratio, and begin flight by running over the surface of the water to gain sufficient forward velocity. Geese were intermediate between dabbling ducks and diving ducks for these three characteristics. Diving ducks however, had the largest heart mass of the three groups (p < 0.0024). Among diving ducks, heart size increased with the foraging depth of each species. It is suggested that heart size in diving ducks reflects a response to diving superimposed upon the demands for flight.
Variation in structural size and wing stripe of Lesser and Greater scaup
Authors: Wilson Steven F. , Ankney C. Davison
Published: March 2009

Heads, wings, and feet of Lesser Scaup (Aythya affinis) and Greater Scaup (Aythya marila) were obtained from 365 birds killed by hunters to investigate differences in structural size and in the intensity and extent of the white wing stripe. Twelve morphological measurements were taken on each bird and wing stripes were quantitatively scored using soil colour charts. Principal component analysis of the structural data separated the birds into two nonoverlapping size groups. We considered the group of large birds and the group of small birds to be Greater and Lesser scaup, respectively. Variation in the wing stripe character was extensive; 9% of the birds in our sample could not be correctly classified as Lesser or Greater scaup on the basis of wing stripe alone. However, most of the variation was due to sexual differences, i.e., female Greater Scaup with unusually dark wings and male Lesser Scaup with unusually white wings.
Descriptions of two unusual new species in the genus Amblyseius Berlese (Acari: Phytoseiidae)
Authors: Yoshida-Shaul E. , Chant D. A.
Published: March 2009

Two unusual new species of Amblyseius, Amblyseius tanzaniensis and Amblyseius urquharti, are described. Amblyseius tanzaniensis is unique among phytoseiid species because of the combination of having seta J1 on the opisthoscutum and having both sublateral setae r3 and R1 inserted on the dorsal shield instead of on the lateral integument. Amblyseius urquharti is one of a few species having seta ZV1 inserted on the ventrianal shield instead of on the surrounding integument. Both species were collected in tropical areas: A. tanzaniensis from Tanzania and A. urquharti from Antigua. Descriptions, figures, and comparisons with similar species are provided for each species.
Trophic relations in a temporary pond: larval salamanders and their microinvertebrate prey
Authors: Taylor Barbara E. , Estes Ruth A. , Pechmann Joseph H. K. , Semlitsch Raymond D.
Published: March 2009

Population densities and diets of larval salamanders and dynamics of their microinvertebrate prey were studied concurrently in 1984 in Rainbow Bay, a temporary pond in Barnwell County, South Carolina. The larvae of Eurycea quadridigitata, Ambystoma talpoideum, and Notophthalmus viridescens fed on a wide variety of small invertebrates, especially cladocerans, chironomid larvae, and ostracods. Electivity was measured using a nonparametric variant of Strauss' linear index. Larvae of all three species showed statistically significant negative electivities toward copepods. Other electivities were less consistent. Smaller, younger larvae of all three species usually consumed higher proportions of cladocerans, and larger, older larvae consumed higher proportions of chironomids. The larvae strongly preferred larger individuals of the cladocerans Daphnia laevis, Pseudosida bidentata, and Simocephalus serrulatus. Production of cladocerans was insufficient to support production of the salamander larvae, and chironomids were probably their energetic mainstay during the latter part of their development. Because microinvertebrate prey remained abundant throughout the period of larval development, we infer that the larvae were not limited by food availability in 1984.
An electronic method for estimating the vaginal and uterine egg content of nematodes, with special reference to ascaridoids
Authors: Smith John W.
Published: March 2009

A Coulter counter is shown to be a practical and sensitive electronic method for estimating the total vaginal and uterine egg content of two species of ascaridoid nematodes. Mean content was 20 000 (range, 5000 – 35 000) in Contracaecum osculatum (9 specimens), and 12 000 (5000 – 24 000) in Hysterothylacium aduncum (16 specimens). The mean number of eggs per milligram body weight was 319 (range, 152–483) in C. osculatum and 377 (218–590) in H. aduncum. The technique may be applicable to other ascaridoids, and perhaps to nematodes in general.
Comparative gill characteristics of Munida quadrispina (Decapoda, Galatheidae) from different habitat oxygen conditions
Authors: Burd Brenda J.
Published: March 2009

The allometric (bilogarithmic) relationship between dry gill weight and organic body weight was compared for benthic galatheid crabs (Munida quadrispina Benedict, 1902) from a low-oxygen fjord and from a normal oxygen population. In the M. quadrispina from the low-oxygen fjord, the slope (b) of the allometric function of gill weight versus body weight was 1.00. This b value was significantly higher (ANCOVA, p < 0.01) than the corresponding slope for the same function in M. quadrispina from normoxic areas (b = 0.63). However, only the largest crabs from the low-oxygen fjord were living consistently in low-oxygen (<0.15 mL/L) conditions; they also had significantly greater (twice as much) relative gill weight than their normoxic counterparts. This observation agrees with findings from previous studies that only the largest M. quadrispina are able to tolerate severe oxygen depletion. Small M. quadrispina from both the low-oxygen fjord and the normoxic area were always found in oxygen concentrations >2.0 mL/L. There were no significant differences between the relative gill sizes of the small crabs from different areas. It was concluded that gill development in M. quadrispina is affected by long-term habitat oxygen conditions. This factor could be important in comparisons of inter- and intra-specific allometric gill functions and in the study of weight-specific oxygen consumption rates of decapod crustaceans.
The effect of experimental termination of lactation on subsequent growth in Peromyscus leucopus
Authors: Derrickson Elissa M.
Published: March 2009

The effect of length of the lactation period on subsequent postnatal growth was examined in the white-footed mouse, Peromyscus leucopus. Litters were separated from the mother at 19, 20, 21, 23, and 25 days after birth. Some individuals in each group lost mass during the 24-h postseparation period, and animals in all treatments showed a significant decline in postnatal growth rate during this period. Average litter growth showed no long-term effect from the timing of mother–offspring separation, with no significant treatment effects after 25 days of age. The timing of mother–offspring separation affected male and female offspring differently, with female offspring mass at 42 days being lowest for females separated later. The timing of mother–offspring separation also affected maternal reproduction such that the timing of weaning was positively correlated with the length of the gestation period of litters conceived at postpartum estrus.
Risk of parasitism and microhabitat selection in juvenile sticklebacks
Authors: Poulin Robert , FitzGerald Gerard J.
Published: March 2009

In laboratory experiments, we tested the following hypotheses: (i) that juvenile threespine (Gasterosteus aculeatus) and blackspotted (Gasterosteus wheatlandi) sticklebacks face higher risks of parasitism by the ectoparasite Argulus canadensis in shallow, vegetated microhabitats and (ii) that they can alter their microhabitat distribution in response to parasites. Reducing water depth increased the number of parasites per infected fish in G. aculeatus and increased the percentage of G. wheatlandi infected. For both species, intensity of infection and percentage of fish infected were greater among fish inhabiting vegetated microhabitats than among fish living in open microhabitats. In the absence of fish, A. canadensis swam near the bottom and in the vegetation. Fish of both species swam near the bottom in the absence of the parasites, but swam near the surface in the presence of parasites. Without parasites, both species of fish preferred to swim in vegetation. With parasites present, the spatial distribution of G. aculeatus changed only slightly, whereas G. wheatlandi became evenly distributed between open and vegetated microhabitats. These results suggest that microhabitat selection by juvenile sticklebacks may serve to reduce the risk of parasitism.
Spacing of female kin in Columbian ground squirrels (Spermophilus columbianus)
Authors: King Wendy J.
Published: March 2009

The dispersion of matrilineally related females was examined within a high-density population of Columbian ground squirrels (Spermophilus columbianus) in southwestern Alberta. Females tended to nest near their natal site when no other female occupied it. Breeding females spaced themselves evenly so that close relatives formed intact groups but not dense clusters. The kin group was typically composed of a mother with one or two daughters that were nonlittermate sisters. Females appeared to be attracted to natal areas and the resources they contained, perhaps burrows.
Macrogeographic variation in mitochondrial DNA of meadow voles (Microtus pennsylvanicus)
Authors: Plante Yves , Boag Peter T. , White Bradley N.
Published: March 2009

Mitochondrial DNA (mtDNA) from 99 meadow voles (Microtus pennsylvanicus) collected in 13 localities and from 2 Townsend's voles (M. townsendii) from a single locality was assayed for restriction fragment length polymorphism (RFLP) with 13 restriction endonucleases. There was evidence of extensive mtDNA sequence heterogeneity within and among meadow vole populations. Thirty-eight different mtDNA composite phenotypes were found. Two common mtDNA composite phenotypes were shared among five populations, the other mtDNA composite phenotypes being characteristic of individual populations. Estimates of nucleon diversity (ĥ) were high (0.303–0.893), as were measures of intrapopulational nucleotide divergence (px values ranged from 0.0 to 0.038). Population fluctuations and periodic dispersal are the likely mechanisms maintaining high mtDNA composite phenotype diversity in meadow vole populations. Overall interpopulational nucleotide divergence (pxy) was also high (values ranged from 0.007 to 0.045). Cluster analysis clearly separates M. pennsylvanicus and M. townsendii and suggests the separation of the meadow vole populations into eastern and central groups, but there is little evidence of structure within the regional groups. Based on the zoogeography of the populations sampled, the mtDNA RFLP data support the differentiation of Microtus pennsylvanicus into at least two previously described subspecies.
Home ranges of free-ranging cats (Felis catus) in Brooklyn, New York
Authors: Haspel Carol , Calhoon Robert E.
Published: March 2009

Home range size is stable among free-ranging cats in Brooklyn, New York. Marked male and female cats had mean home ranges of 2.6 (95% CI, 2.38–2.87) and 1.7 ha (95% CI, 1.57–1.98), respectively, as estimated by the population utilization distribution. Males had significantly larger home ranges, used the perimeter of their ranges more, and had greater variability in home range size than females. Gender differences in body weight accounted for observed differences in home range size; the seeking of estrous females by males could not account for differences in male and female home ranges. The availability of garbage or abandoned buildings, neighborhood, season, or experimental supplementary feeding did not influence home range size.
The functional significance of adrenergic pH regulation in fish erythrocytes
Authors: Tufts Bruce L. , Randall D. J.
Published: March 2009

Experiments were conducted in vitro to determine the presence or absence of an adrenergic pH effect in the erythrocytes of Squalus suckleyi, Raja binoculata, and Oncorhynchus tshawytscha. Adrenergic stimulation significantly increased the erythrocyte pH of Oncorhynchus tshawytscha, but did not significantly affect the erythrocyte pH of Squalus suckleyi or Raja binoculata. The results support the view that the functional significance of adrenergic pH regulation in fish erythrocytes is to offset the reduction in blood oxygen carrying capacity caused by the Root effect.
Importance of individual species of predators on nesting success of ducks in the Canadian Prairie Pothole Region
Authors: Johnson Douglas H. , Sargeant Alan B. , Greenwood Raymond J.
Published: March 2009

We followed 3094 upland nests of several species of ducks. Clutches in most nests were lost to predation. We related daily nest predation rates to indices of activity of eight egg-eating predators, precipitation during the nesting season, and measures of wetland conditions. Activity indices of red fox (Vulpes vulpes), striped skunk (Mephitis mephitis), and raccoon (Procyon lotor) activity were positively correlated, as were activity indices of coyote (Canis latrans), Franklin's ground squirrel (Spermophilus franklinii), and black-billed magpie (Pica pica). Indices of fox and coyote activity were strongly negatively correlated (r = −0.51), as were those of badger (Taxidea taxus) and skunk (r = −0.46). Nest predation rates in the early part of the breeding season were positively related to indices of fox, American crow (Corvus brachyrhynchos), and badger activity. Predation rates in the latter part of the season were positively related to indices of fox and skunk activity. Predation rates on early-season nests were lower in areas and years in which larger fractions of seasonal wetlands contained water. For late-season nests, a similar relationship held involving semipermanent wetlands. We suspect that the wetland measures, which reflect precipitation during some previous period, also indicate vegetation growth and the abundance of buffer prey, factors that may influence nest predation rates.
Physiological disturbances in rainbow trout (Salmo gairdneri) during acid and aluminum exposures in soft water of two calcium concentrations
Authors: Playle Richard C. , Goss Greg G. , Wood Chris M.
Published: March 2009

Rainbow trout (Salmo gairdneri) fitted with dorsal aortic cannulae were exposed in a flow-through soft water system to three acidities (pH 5.2, 4.8, or 4.4) and two concentrations of Ca (45 or 410 μequiv.∙L−1), in the presence (105 μg∙L−1) or absence of Al. Blood was sampled for respiratory gases, ions, metabolites, and hematology before and at 4, 18, 28, 42, and 66 h exposure. Two toxic mechanisms of Al and acidity were seen: (i) ionoregulatory toxicity, which was caused by Al at pH 5.2 and 4.8 and by acidity at pH 4.4, and (ii) respiratory toxicity, which was caused solely by Al, and was greatest at higher pH. Ionoregulatory toxicity involved decreases in plasma Na+ and Cl−, red cell swelling, and hemoconcentration. Respiratory toxicity involved reduced blood oxygen tension, elevated blood carbon dioxide tension, and increases in blood lactate. Blood acidosis was a combination of respiratory acidosis (due to CO2 accumulation in the blood; higher pH exposures) and metabolic acidosis (probably due to differential Na+ and Cl− loss into the external, acidic environment; lower pH exposures). Higher water Ca reduced ionoregulatory disturbances due to acidity alone but not those due to Al at higher pH. Higher water Ca also reduced respiratory disturbances at lower pH but not at higher pH. The results are discussed with reference to the chemistry of Al and changes in the gill epithelium associated with acid and Al exposure.
Pair formation, duration of pair-bonds, and mate replacement in a population of beavers (Castor canadensis)
Authors: Svendsen Gerald E.
Published: March 2009

Characteristics of the breeding units in a population of North American beavers (Castor canadensis) are presented. All breeding units were monogamous. The hypothesis that a successful pair-bond usually occurs between an older and larger female and a younger and smaller male was rejected. Fifty-six percent of all pairs were formed in the months of September, October, and November. Newly formed pairs occurred predominantly between a resident beaver that had not yet acquired a mate, or had lost a previous mate, and an immigrant. A 2-year-old size beaver was one of the pair mates in 90% of newly formed pairs. The average pair-bond lasted 2.5 years. The length of a pair-bond was associated with conditions at the site of residency; beavers living in the more stable conditions (lake sites) remained together longer than did beavers living in comparatively unstable conditions (stream sites). Loss of the male was the cause of 39% of the breakups of pairs, loss of the female, 61%. Desertion was documented in 4%. Because of the age discrepancy at the time of pairing, death of one of the mates was presumably the major cause of mate turnover.
Feeding behaviour and distance from burrows of Columbian ground squirrels
Authors: Andrusiak Lorraine A. , Harestad Alton S.
Published: March 2009

Percent cover of clover, a highly preferred forage of Columbian ground squirrels (Spermophilus columbianus), increased with increasing distance from burrows. Ground squirrels feeding far from burrows consumed more clover and during the first 10 min of a feeding bout fed at greater rates than did ground squirrels feeding near burrows. Body weights did not differ between feeding locations. Because abundance of preferred forage as well as risk of predation increases with increasing distance from burrows, the feeding behaviour of ground squirrels is mediated by time budgeting and differs with distance from burrows.
The ecology of beach-dwelling Peromyscus maniculatus on the Pacific Coast
Authors: Marinelli Lui , Millar John S.
Published: March 2009

Live- and snap-trapped Peromyscus maniculatus from Barkley Sound, B.C., were compared between beach and inland habitats as well as between island and mainland populations. Densities, as indicated by trapping success, were not consistently different between beach and inland habitats, although the islands appeared to be more densely populated than the mainland. Mice in beach and inland habitats showed fidelity to those sites. Pregnancy rates were higher in beach habitats than in inland habitats. Beach mice were also larger, but less fat, than inland mice. We suggest that future comparisons between island and mainland populations take into consideration the variance in demographic and morphological parameters within, as well as among, islands.
Alpine spiders and harvestmen of Mount Rainier, Washington, U.S.A.: taxonomy and bionomics
Authors: Crawford Rodney L. , Edwards John S.
Published: March 2009

Resident spiders and harvestmen were collected (largely by pitfall trap) at eight sites from 1930 to 3230 m elevation on Mount Rainier (4392 m), Cascade Mountains, ranging in environment from subalpine heath shrub meadow to essentially unvegetated aeolian zone. Records and taxonomic and ecological notes are given for the 31 species taken. Two new linyphiid spiders are described in the genera Scotinotylus and Meioneta; Scotinotylus autor (Chamberlin) and Coreorgonal petulcus (Millidge) are proposed as new combinations. The female of Scotinotylus bicavatus Millidge is redescribed and a description of the male is given, with a report of a gynandromorph specimen and new synonymy of Scotinotylus bipoculatus Millidge. Several other linyphiid species are illustrated. Variation is discussed in the linyphiids Erigone paradisicola Crosby and Bishop, S. bicavatus, and Tennesseellum formicum Emerton and the gnaphosid Micaria constricta Emerton. Included are the first valid North American records of the linyphiid Walckenaeria vigilax (Blackwall) and the first United States records of the phalangiid harvestman Liopilio glaber Schenkel. Samples from 1930 to 2250 m showed similar species richness; above 2250 m, numbers of species decreased but abundance of trapped individuals did not. At the highest site, 3230 m, two species exploit windblown arthropod fallout: the nocturnal L. glaber and the diurnal lycosid spider Pardosa rainieriana Lowrie and Dondale.
Determination of digesta fill and passage rate from nonabsorbed particulate phase markers using the single dosing method
Authors: Holleman D. F. , White R. G.
Published: March 2009

A method is given for analyzing particulate digestive marker data in terms of digesta fill, fecal output, and digesta passage times. The method applies the Stewart – Hamilton Principle to data obtained from a single marker dosing followed by feces sampling; it assumes steady-state conditions for the digesta, but makes no assumptions concerning compartmentalization of digesta. Data analyses are presented for an experiment with sheep in which a particle phase marker, cerium-141 chloride, was used. The estimate of fecal output obtained was 1.8 ± 2.2% (mean percent difference ± SE) greater than the actual fecal output; the in vivo estimate of total digesta fill was 3.3 ± 3.4% less than measured digesta fill. For comparison, the present data were also analyzed using two established compartment modeling approaches, namely a time-independent and a time-dependent two-compartment model. The only significant difference between the estimated parameters as obtained from the Stewart – Hamilton method and the compartmental models was a significantly shorter transit time as estimated by the time-dependent model.
Temperature-dependent development in Pseudocalanus species
Authors: McLaren I. A. , Sévigny J.-M. , Corkett C. J.
Published: March 2009

The duration of embryonic development and that of well-fed older stages were determined for Pseudocalanus acuspes, P. minutus, P. moultoni, and P. newmani. Excluding abnormal individuals, the times for older stages were lognormally distributed, with similar variances among species, stages, and temperatures. Some residual variance occurred among families reared together. Copepod rearings should take these sources of variance into account. Development times (D) were described well by Bělehrádek's temperature (T) function, D = a(T − α)−b, with b = 2.05 for all species from previous studies, and α and a fitted for embryonic development. Only a needed to be fitted for older stages (i.e., "equiproportional" development). Relative times to given stages at all temperatures (i.e., relative values of a) were similar in three species, but P. minutus deviated from this pattern. Values of α were directly related to presumed environmental temperatures in the species' ranges. Values of a were directly related to egg and body sizes of the different species. The temperature functions can be used to predict the lengths of the generations in these four species in nature when food is adequate.
Experimental demonstration that scent marking can predict dominance in the woodchuck, Marmota monax
Authors: Hébert Paule , Barrette Cyrille
Published: March 2009

Scent marking is known to be related to dominance in mammals. Here we ask whether the isolated scent from the oral glands of woodchucks (Marmota monax) can advertise dominance. The scent of an individual was presented to a conspecific before the two met and could establish a dominance–subordination relationship. For all 19 dyads that would later express aggressive dominance, the individual pre-encounter rate of scent marking was the same no matter the sex, composition of the dyad, or the future status of the individual. However, when they were presented with scent marks of a conspecific (before meeting the marker), future subordinates marked the scent of future dominants more than vice versa (Mann–Whitney U-test, Z = 2.246, [Formula: see text]). The status of members of dyads was accurately predicted from the pre-encounter marking performance in 14 of the 19 dyads (χ2 = 3.368; 0.10 > p > 0.05). This suggests that scent, by itself, conveys information on the dyadic dominance status of an individual relative to the receiver of the olfactory signal.
Responses of meristic characters in chum salmon (Oncorhynchus keta) to temperature changes during development
Authors: Murray Clyde B. , Beacham Terry D.
Published: March 2009

Variability in the number of dorsal, anal, caudal, pectoral, and pelvic fin rays, vertebrae, and gill rakers was examined in four populations of chum salmon (Oncorhynchus keta) transferred from 8 to 2 °C at various stages of embryonic development. Late transfers at complete eye pigmentation produced more gill rakers than transfers earlier in development. Transfers at completion of epiboly and initial eye pigmentation produced fewer vertebrae than earlier or later transfers. Stage of transfer had no significant effect on fin ray counts. Vertebral responses differed among families. Genotype–environment interactions produce meristic phenotypes that are presently difficult to predict.
Description of Mycale bamfieldense n.sp. (Porifera, Demospongiae, Poecilosclerida) from Vancouver Island, British Columbia
Authors: Reiswig H. M. , Kaiser H.
Published: March 2009

A new species of Porifera, Mycale banfieldense (Demospongiae, Poecilosclerida), is described from a semiobscure, intertidal cavern of the outer coast of Vancouver Island, British Columbia, Canada. This is the first species of Mycale from the Pacific basin known to possess micracanthoxea microscleres, and only the second such species worldwide. These microscleres, which average 4.2 × 0.2 μm, are the smallest sponge spicules discovered to date. They are formed individually within cytoplasmic vacuoles of anucleolate scleroblasts but each scleroblast contains 20 to 50 similar spicules.
Structure of shells from eggs of the geckos Gekko gecko and Phelsuma madagascarensis
Authors: Packard Mary J. , Hirsch Karl F.
Published: March 2009

The geckos Gekko gecko and Phelsuma madagascarensis lay small, round eggs with brittle, inflexible shells. Eggshells of both species consist of a thick calcareous layer with an organic layer adhering to the outer surface and a thin, fibrous shell membrane attached to the inner surface. The calcareous layer consists of calcium carbonate in the form of calcite, and is organized into ill-defined columns that form a dense crystalline matrix. The inner face of columns (the aspect attached to the shell membrane) consists of crystallites of variable size and morphology. Eggshells contain a great deal of organic matter, and prolonged treatment with NaOH leaves the calcareous layer riddled with horizontal fissures reflecting the removal of organic matrix. Pores through the calcareous layer of eggshells of both species terminate at the outer surface in a variable number of small openings. The pore canal in G. gecko eggshells occurs as a series of labyrinthine channels in a calcareous concretion that fits loosely within a corresponding cleft in the calcareous layer. Detachment of the concretion leaves a shallow pit or depression on the inner surface of the eggshell. We observed concretions and pits in P. madagascarensis eggshells but were unable to characterize the nature of the pore canal in this species.
Seasonal body weight, body condition, and lactational trends in muskoxen
Authors: White R. G. , Holleman D. F. , Tiplady B. A.
Published: March 2009

Seasonal patterns of body weight, fat, protein, milk quality (dry matter content), and milk production rate were determined for three sexually mature female muskoxen (Ovibos moschatus) over three consecutive lactation periods. Females were allowed to graze in summer and had access to hay year-round. A high-protein pelleted ration supplemented this diet. Following calving in early May (1984, 1986) or June (1985), body weight remained constant throughout the summer, body fat declined for 3–5 weeks after calving, and body protein declined transiently during the latter period. Almost all annual gains in body weight and body fat occurred during the 6- to 8-week rutting period from mid-August to mid-October. High milk production (1.3–2.4 L/d) occurred 3 weeks post-calving, generally remained high for another month, and declined to 1.2 ± 0.15 L/d (mean ± SEM) just before the rut. A major decline in milk production, to 0.44 ± 0.050 L/d, occurred during the rut. Although milk dry matter increased 33% ± 4.3% during the rut, this increase was offset by the 60% ± 6.4% decline in milk production. All females successfully reproduced each year of the study and no evidence was found for a lactational anestrum. The hypothesis that gains in body weight must be made before the rutting period to maximize conception rate was rejected. This study highlighted the importance to lactating muskoxen of the late summer – early winter period for annual regain in body weight and body fat, which occurred concurrently with ovulation and conception.
Fossil muskoxen of Ohio
Authors: McDonald H. Gregory , Davis Richard Arnold
Published: March 2009

Two species of muskoxen have been found as fossils in Ohio's Pleistocene deposits, the extinct Symbos cavifrons and the extant Ovibos moschatus. Symbos currently is represented by six specimens, and Ovibos, by two; all specimens are brain-cases. One of the Ovibos was found in Hamilton County, Ohio, in Wisconsinan gravels associated with the Miami Sublobe of the Huron Lobe; this new record is the southernmost for the genus. All records of Symbos in Ohio are Late Pleistocene, suggesting that the genus expanded into the region shortly after deglaciation. Both records of Ovibos from the state are associated with the glacial margin.
Late Pleistocene zoogeographic shifts and new collecting records for Helophorus arcticus Brown (Coleoptera: Hydrophilidae) in North America
Authors: Morgan Alan V.
Published: March 2009

Helophorus arcticus Brown is a rare hydrophilid beetle, previously known from localities in subarctic and eastern Canada. New sites, including the first record for the province of Quebec, are described with the modern habitats, and climatic records are provided for the known range of the species. Fossil specimens of H. arcticus are known from both early and late Wisconsinan sites in southern Canada and the northern United States. The movement of the species is hypothesized from the last (Sangamonian) Interglacial to the present together with potential new collecting areas in subarctic North America.