bluuebunny/crossref_metadata_2025 huggingface dataset:
Kyopoda lamberti gen.nov., sp.nov., an atypical stauromedusa (Scyphozoa, Cnidaria) from the eastern Pacific, representing a new family
Authors: Larson R. J.
Published: March 2009

A new stauromedusa, Kyopoda lamberti gen.nov., sp.nov., is described from British Columbia and California. Unlike all other known Stauromedusae, which have their stomach and gonads in the calyx, this small vermiform species has these structures in a sac-like swelling at the base of the stalk. Because of this characteristic it is placed in a new family, the Kyopodiidae. Its systematic position within the Eleutherocarpida is unknown.
Acid–base and electrolyte responses to low pH maintained by phosphate–citrate buffers in the bathing medium of the larval salamander Ambystoma tigrinum
Authors: DeRuyter Marie L. , Stiffler Daniel F.
Published: March 2009

Larval Ambystoma tigrinum were exposed to an external pH of 3.5 to 7.5 using phosphate – citrate buffers in the bathing medium. Blood analysis of cannulated Ambystoma tigrinum at pH 5.5, 4.5, and 3.5 indicated their ability to maintain relatively stable arterial pH at the two higher values; however, at pH 3.5, the blood pH diminished over the 12-h period before death. The greater stability of arterial pH at higher external pH is partially due to a reversal of an initial increase in arterial [Formula: see text]. This may not be due entirely to pulmonary excretion of CO2 as it also occurred in animals that were forced to exchange gases solely across the skin – gill unit by being deprived of access to an air space. This result suggests increased skin – gill perfusion and (or) ventilation as a mechanism for lowering arterial [Formula: see text]. Sodium transport across the skin of A. tigrinum was measured over a buffered pH range of 3.5 to 7.5. Na+ influx decreased from 1.0 ± 0.1 μequiv. 10 g−1 h−1 (mean ± SEM) at pH 7.0 to 0.1 ± 0.1 μequiv. 10 g−1 h−1 at pH 3.5. Na+ efflux increased to 38.1 ± 8.7 μequiv. 10 g−1 h−1 from 4.1 ± 0.9 μequiv. 10 g−1 h−1 as pH declined from 7.0 to 3.5. Calcium added to the buffer at pH 4.5 decreased Na+ efflux at that pH. Na+ fluxes measured in nonbuffered, low-pH solutions revealed qualitatively similar patterns with lower efflux rates and lower critical pH values.
A review of possible explanations for reverse size dimorphism of American woodcock
Authors: Keppie Daniel M. , Redmond Gerald W.
Published: March 2009

Female American woodcock (Scolopax minor) exceed males in body size. The degree of dimorphism in American woodcock is greater than in many other shorebird species and is comparable to that in many accipiter hawks and owls. We examine three hypotheses that have been used to explain dimorphism for other avian species: that dimorphism enhances niche utilization by reducing intersexual competition for food, that large female size improves reproductive effort, and that males are small because of selection for agile display flights. Evidence is lacking, weak, or contradictory that any one of these three general hypotheses sufficiently explains reverse dimorphism in American woodcock. Despite our objections to the hypotheses, we point out needed research to elucidate better their ability to explain dimorphism. We speculate that selection pressure on males for early arrival and acquisition of territories also influences their small size.
Demography during a population crash of the wood lemming, Myopus schisticolor
Authors: Bondrup-Nielsen Søren , Ims Rolf Anker
Published: March 2009

Four-year microtine population density cycles are extreme in northern Fennoscandia. We studied populations of wood lemmings (Myopus schisticolor) and bank voles (Clethrionomys glareolus) in the peak phase and subsequent crash phase at two localities, Varaldskogen and Risberget, Norway. Bank voles at Varaldskogen and bank voles and wood lemmings at Risberget crashed during the nonreproductive period in winter when we were not trapping animals. Wood lemmings at Varaldskogen, however, crashed during the reproductive period in summer. Reproduction in the wood lemming population was as intense during the summer crash as in the peak phase. Further, survival of overwintered animals was the same in peak populations and in the population undergoing the crash. However, lack of recruitment was the cause of the summer crash of the wood lemming population. Poor nutrition is the most likely cause of the lack of recruitment.
Influence of the amino acid balance on the improvement of an artificial diet for a biotype of Acyrthosiphon pisum (Homoptera: Aphididae)
Authors: Febvay G. , Delobel B. , Rahbé Y.
Published: March 2009

A green biotype of the pea aphid, A. pisum, from Lusignan (France), showed very poor performance on the standard Akey and Beck diet. Significant improvement occurred after reduction of the osmotic pressure of the diet and modification of the amino acid component, according to the results of carcass analysis. A further improvement was obtained through an optimalization of the aromatic amino acid level: the tyrosine deficiency induced by its poor solubility was overcome by an excess of phenylalanine and the inclusion of a soluble tyrosine compound, β-alanyltyrosine. A new diet was therefore formulated for this biotype, on which adults were more than twice as heavy as on the standard diet.
Pigmentation, size, and migration of elvers (Anguilla rostrata (Lesueur)) in a coastal Rhode Island stream
Authors: Haro Alexander J. , Krueger William H.
Published: March 2009

Progressive pigmentation of Anguilla rostrata elvers was very similar to that described for A. anguilla. Pigmentation increased rapidly with the advancing season, while total length decreased. The increase in pigmentation was independent of the decrease in length and may have been influenced by increased contact with the substrate. Mean lengths showed significant differences within seasons and between years, and the range of variation was greater than that described by V. D. Vladykov (1966. Verh. Int. Ver. Theor. Angew. Limnol. 16: 1007–1017) for elvers collected from Maryland to Quebec. We substantiate Vladykov's finding that elver size tends to increase with increasing distance from the spawning area, but reject his size/sex hypothesis. The main migration occurred in April and May and was related to decreasing water depth and rising stream temperature. Elvers took about 4 weeks to ascend 180 m above the tidal zone, probably because of a high stream gradient and the absence of tidal influence.
Agonistic behavior among mountain goats foraging in winter
Authors: Masteller Mark A. , Bailey James A.
Published: March 2009

During two winters we studied agonistic behavior of foraging mountain goats (Oreamnos americanus) in both natural and manipulated conditions. By maintaining food pellets at bait site we tested two hypotheses: (i) dominant goats will have primary access to the food, and (ii) kids of dominant nannies will have access to the food with their mothers. At the bait site, average group size was larger and goats in each sex–age class were more aggressive compared with those away from the site. The dominance order among sex–age classes at the bait was similar to that reported at mineral licks, except that 2-year-old males dominated adult females. When goats fed at the bait site, adult females with kids were very aggressive and nanny–kid distances decreased. At the bait, an orphan kid received much aggression, while kids with their mothers received few threats. At the bait site, dominant goats had primary, but not exclusive, access to the bait and kids fed with their mothers, which supported our hypotheses.
Environmental variation and habitat separation among small mammals
Authors: Vickery William L. , Iverson Stuart L. , Mihok Steve , Schwartz Bill
Published: March 2009

Habitat use and population density of five species of forest small mammals were monitored by annual spring snap-trap censuses at Pinawa, Manitoba, over 14 years. Population sizes were positively correlated among species and showed no evidence of density-dependent effects. Species were habitat selectors. Habitat use by species did not vary among years. Habitat separation between the dominant species was not correlated with environmental variables or with population size. We suggest that habitat selection and positive covariance among species abundances are the principal factors characterizing the dynamics of this community.
The effects of feeding and ecdysis on temperature selection by young garter snakes in a simple thermal mosaic
Authors: Gibson A. Ralph , Smucny Darlene A. , Kollar John
Published: March 2009

Temperature selection by five young common garter snakes, Thamnophis sirtalis, was studied using a simple, two-choice thermal mosaic. The animals were housed in an arena (60 × 120 cm) within an environmental room, where they were exposed to a photoperiod of 12 h light: 12 h dark and a general ambient temperature of 20 °C. The arena contained two shelters (20 cm × 20 cm), one at ambient temperature and one heated to 30 °C. On a given day, we determined the snakes' locations in the arena twice an hour for several hours. Observations were made in this manner on most days over a period of 19 weeks. Within 1 h following a late afternoon feeding, use of the hot shelter increased from about 5–20% of observations to above 80%. Occupation of the heated shelter remained at a high level the next day and then decreased, reaching a background of 10–40% by the 3rd day after feeding. The animals displayed a higher background use when maintained on a weekly feeding regime than they did when on a biweekly regime. During a 5-day period preceding ecdysis, occupation of the hot shelter again exceeded 80% of observations; decline to a background of 0–10% began about the day of molt. Runs tests performed on the daily records of individuals indicate that hot-shelter use tended to occur in bouts. There was no suggestion of diurnal variation in thermoregulatory behavior.
Effects of learning on food selection and searching behaviour of deer
Authors: Gillingham Michael P. , Bunnell Fred. L.
Published: March 2009

A review of feeding habits in black-tailed deer (Odocoileus hemionus columbianus Richardson) reveals considerable variation among animals, locations, and seasons. Since the processes affecting food selection are poorly understood, we explored the concept of optimal foraging as a means of predicting foraging behaviour of black-tailed deer. Food preference was initially determined for three foods under ad libitum conditions. We then studied the feeding behaviour of two deer using the same foods in a 0.5-ha enclosure and examined the effects of experience, density, and distribution of their preferred food on diet selection. When deer had to search for food, diet selection remained the same as ad libitum preference when preferred foods were abundant. Both animals became more efficient (intake per distance travelled) at finding preferred foods with increased experience in a particular food distribution. This was accomplished by repeating search paths that had been effective during previous trials. Consequently, performance was poor when the food distribution was changed. Under controlled conditions, memory of previous foraging events can play a role in food selection by deer. Description of a foraging bout as a static process ignoring its internal dynamics may be convenient but misleading.
Body temperatures and movements of hibernating snakes (Crotalus and Thamnophis) and thermal gradients of natural hibernacula
Authors: Macartney J. Malcolm , Larsen Karl W. , Gregory Patrick T.
Published: March 2009

Although temperate zone snakes spend a large part of each year in hibernation, we know relatively little about their behavior during this part of the annual cycle. We used radiotelemetry to monitor temperatures and movements of hibernating rattlesnakes (Crotalus viridis) in southern British Columbia and garter snakes (Thamnophis sirtalis) in northern Alberta, and measured thermal profiles inside their hibernacula. A reference site near the garter snake hibernaculum, superficially resembling a winter den but not used by snakes, also was monitored. A thermal gradient (temperature increasing with depth) formed during the winter in the rattlesnake den, but only minimally so in the garter snake den. Differences in thermal profiles were attributed to differences in subsurface geomorphology. The reference site exhibited much greater temperature fluctuation than the den itself, with lethal temperatures prevailing throughout the winter. Therefore, suitable hibernation sites may be limited in some areas despite a superficial appearance of abundance. As ambient temperatures declined during early winter, snakes made lateral movements inside their hibernacula, and exhibited changes in body temperature which we interpreted as movements to warmer (deeper) microsites. Body temperatures recorded during winter ranged between 2 and 7 °C. In early spring the thermal gradient collapsed and the rattlesnake den gradually underwent a uniform increase in temperature. A similar increase in subterranean temperatures occurred in the garter snake den. Temperature change was perhaps a stimulus for emergence in rattlesnakes, but possibly not in garter snakes. The hypothesis that hibernating snakes orient along a seasonally reversing thermal gradient is not unambiguously supported.
How far do animals move? Routine movements in a tortoise
Authors: Hailey Adrian
Published: March 2009

Although many aspects of the ecology and physiology of animal movement have been well studied, little is known about the distance moved during routine activity. To examine this problem, daily movements of adult tortoises Testudo hermanni were measured by thread trailing. The activity season was about 210 days per year; individual tortoises were active on 95% of days from April to June, but only on 49% of days in the dry months, July–October, probably because of a digestive bottleneck caused by dry food. Daily movements ranged from 1 to over 450 m, with a daily mean over a year of 80 m in males and 85 m in females; there was significant variation between months. Daily movements were 5–10 times less than those of similarly sized mammals. Individuals were active on average for 140 days per year, moving a total of about 12 km. Routine movements occurred within home ranges of 1.8 ha. The intensity of use of the home range was thus 12 km/1.8 ha, equivalent to annual sampling of a strip 1.5-m wide. Food plants were approached over distances of 1–2 m, so that on average all points within the home range were sampled for food once per year; mates were detected over much larger distances. Tortoises used many refuges spread throughout the home range, and rarely returned to the same refuge. Most refuges were insubstantial and gave only concealment and shade; only one-third provided physical protection. This pattern of refuge use is permitted because tortoises have an armoured carapace, the transport of which is estimated to be energetically less expensive than daily return to an environmental refuge.
The influence of distance to refuge on flight initiation distance in the gray squirrel (Sciurus carolinensis)
Authors: Dill Lawrence M. , Houtman Robert
Published: March 2009

Gray squirrels (Sciurus carolinensis) typically run to the nearest tree to escape from predators they encounter while foraging on the ground. As the risk of capture increases with distance from the refuge tree, squirrels feeding far from trees should have greater flight initiation distances than those feeding closer by. This prediction was confirmed: flight initiation distance in response to a motorized model predator (a cat) increased as distance to refuge increased. This could not be attributed to any effect of distance to refuge on vigilance.
The distribution of conspecific nest parasitism in birds
Authors: Rohwer Frank C. , Freeman Scott
Published: March 2009

Conspecific nest parasitism is much more common in birds that have self-feeding young than in those with parentally fed young. We review evidence for this pattern and suggest that it is produced by a fundamental dichotomy in selection pressure for defense against conspecific parasites. Species that feed their young should experience intense selection pressure for effective defense against parasitism, because their reproductive output is limited by post-hatching parental care. Species that have self-feeding young, however, experience only mild selection for parental defense against parasites, because their reproductive output is constrained chiefly by their ability to produce eggs. For such birds, parental care can be shared with little or no detriment to survival of young. Within both the self-feeders and the birds that feed their young the occurrence and intensity of conspecific nest parasitism is dictated primarily by the ability of parasitic females to find host nests. This pattern is particularly clear among waterfowl, where conspecific nest parasitism is frequent in ducks that nest in cavities, over water, or in high densities on islands. We review evidence that suggests greater conspecific nest parasitism for parentally fed species that nest in colonies than parentally fed species with dispersed nests. We also make predictions about the distribution of conspecific nest parasitism in nonavian groups.
Response of radio-collared moose to a large burn in central Alaska
Authors: Gasaway W. C. , Dubois S. D. , Boertje R. D. , Reed D. J. , Simpson D. T.
Published: March 2009

Responses of radio-collared moose (Alces alces) to a 500-km2 burn in central Alaska were described using prefire and postfire movements. Moose with low prefire contact with the burned area increased use following the fire. Increased use resulted from moose shifting home ranges and allocating more time to areas previously used for migration. Moose with high prefire contact decreased use following fire. Moose with no known prefire contact did not use the burn despite their close proximity to the burn. Increased use of the burn and establishment of new annual movement patterns occurred largely during the 1st year following the fire. Increased use of the burn was seasonal (June – September). No relationship was found between age of moose and increased use of the burn. Traditional movement patterns apparently prevented study moose without prefire use, irrespective of age, from finding the burn. Managers should obtain greatest use of burned habitat in areas where moose are abundant and (or) along major migration corridors where density is low but the number of moose passing through is high.
Kudoa thyrsites (Gilchrist, 1924) (Myxozoa) in the cardiac muscle of Pacific salmon (Oncorhynchus spp.) and steelhead trout (Salmo gairdneri)
Authors: Kabata Z. , Whitaker D. J.
Published: March 2009

An examination of the cardiac muscle of returning adults of all species of British Columbia Pacific salmonids, including steelhead trout (Salmo gairdneri), for infection by the myxozoan parasite Kudoa thyrsites showed that all species but chum (Oncorhynchus keta) and sockeye (Oncorhynchus nerka) are susceptible to infection. The prevalence of observed infection was low. Its intensity was not determined, but the small numbers of spores observed suggest that it was low. The possible causes of these observations are discussed.
Parental care and foraging ability in male water bugs (Belostoma flumineum)
Authors: Crowl Todd A. , Alexander Jr. James E.
Published: March 2009

The predatory water bug Belostoma flumineum is one well-known insect example of male parental care. Male water bugs, while brooding eggs, may suffer several potential costs. These include the following: energetic costs, increased vulnerability to predation, and decreased foraging ability. We conducted investigations to determine whether encumbered males exhibited decreased foraging ability on two different prey types: fast moving fish (Gambusia affinis) and slower moving snails (Physella virgata virgata). Encumbered males encountered and captured snails at the same rate as did unencumbered males and females; however, encumbered males were less likely to encounter and capture the more mobile Gambusia than were unencumbered males and females. These results demonstrate that the magnitude of parental care costs in Belostoma depends in part on the relative abundance of sessile and mobile prey.
Evolutionary and ecological significance of genome sizes in the copepod genus Pseudocalanus
Authors: McLaren I. A. , Sévigny J.-M. , Frost B. W.
Published: March 2009

Feulgen microspectrophotometry revealed wide variation within and among six species of Pseudocalanus in estimated amounts of DNA in diploid somatic nuclei of adults. Because of similar numbers of nuclei within stages across species, body sizes and temperature-corrected development times of embryos and older stages were positively correlated with these genome sizes, with adaptive consequences for life-history and production characteristics. The six genome sizes among Pseudocalanus, together with those of seven species of Calanus, form a highly significantly nonrandom series of ca. 4, 8, 13, 17, 21, and 25 pg DNA/nucleus, not attributable to polyploidy. This pattern could reflect abrupt and perhaps sympatric speciation.
The effect of decerebration and anesthesia on the reflex responses to hypoxia in catfish
Authors: Burleson Mark L. , Smatresk Neal J.
Published: March 2009

The ventilatory and cardiovascular responses of conscious, decerebrate, and anesthetized spontaneously breathing (ASB) catfish (Ictalurus punctatus) were measured at three different water O2 tensions [Formula: see text] to determine the advantages and limitations associated with each experimental preparation. Ventilation of the decerebrate and ASB catfish was assisted to maintain arterial [Formula: see text] levels and acid–base balance at values similar to those of conscious fish. All groups exhibited decreased heart rate (fh) and increased dorsal aortic blood pressure (PDA), and increased either ventilatory rate (fg), opercular pressure (POP), or both during hypoxia. Conscious catfish were extremely sensitive to outside disturbances and responded with transient bradycardia and apnea. The fg of decerebrate fish was consistently high and was little affected by changes in [Formula: see text]. Altered ventilation after decerebration may be due to interference with suprapontine structures involved in the control of ventilation. Unlike conscious fish, both decerebrate and anesthetized fish had maximal heart rates in normoxia and responded to hyperoxia by reducing fh. Anesthesia produced a relative tachycardia and attenuated the hypoxic bradycardia of ASB catfish, but had little effect on ventilatory reflex responses to hypoxia.
Demographic responses of arctic hares (Lepus timidus) to experimental reductions of red foxes (Vulpes vulpes) and martens (Martes martes)
Authors: Marcström Vidar , Keith Lloyd B. , Engren Erik , Cary John R.
Published: March 2009

This study aimed, through a field experiment, to test predictions from two hypotheses: (i) predation is a factor limiting arctic hare (Lepus timidus) populations, and (ii) predation shifts to arctic hares when voles (Microtus and Clethrionomys) decline to scarcity. Our approach was to compare demographic characteristics of hare populations on two large islands (Rånön, 2350 ha, and Bergön, 1800 ha) in the northern Baltic, where foxes (Vulpes vulpes) and martens (Martes martes) were alternately present in normal numbers or reduced by snaring and shooting over winter. Hare densities in March, as indexed by transect counts and estimated by Jolly–Seber analyses, averaged two to three times higher on each island during years with reduced numbers of foxes and martens. Rates of population increase on Rånön, and thus population trends, were correlated with annual survival of adults and yearlings, but more strongly with survival of juvenile hares from birth to March (indexed by recruitment). Survival estimates were incomplete for Bergön and could not be similarly analyzed. Hare survival rates were lowest on Rånön during the 3 years when vole populations had declined to cyclic lows, but adult and yearling survival dropped only slightly during the vole low that coincided with reduced fox and marten numbers. We conclude that fluctuations were imposed on Rånön's hare population by the vole cycle's effect on predation rates, whereas on both islands major differences in population levels between groups of years were largely due to the number of foxes and martens present. Demographic differences between hare populations of Rånön and Bergön, apparently unrelated to predation, included dispersal rates, mean body weights of females, and mean first-litter conception dates. Densities, survival rates, and natality are compared with selected arctic hare populations elsewhere.
Thermoregulation in winter-acclimatized common eiders (Somateria mollissima) in air and water
Authors: Jenssen Bjørn Munro , Ekker Morten , Bech Claus
Published: March 2009

Metabolic heat production, body temperature, and skin temperatures of the back and breast were measured and the thermal conductance, and thus insulation, estimated in winter-acclimatized common eiders (Somateria mollissima) exposed to air and water. When exposed to low air temperatures, the plumage was responsible for most of the insulation. When exposed to water, the insulation in the plumage was reduced. This decrease was, however, compensated through increased peripheral vasoconstriction. A low total thermal conductance lowers the energetic costs of existence in cold environments. This reduces the nutritional demands, and may be an adaptation to living in polar and subpolar regions where temperatures are low and where the short day length during winter may reduce the time available for feeding.
Are probability estimates from the permutation model of Mantel's test stable?
Authors: Jackson Donald A. , Somers Keith M.
Published: March 2009

Matrix comparison tests (i.e., Mantel's test or quadratic assignment) are employed with increasing frequency to measure the concordance between genetic, behavioural, morphological, ecological, and geographic distances. Such tests compare an observed measure of matrix association with a null distribution derived from a randomly generated subset of all possible permutations of one of the original matrices. Typically, 500–2000 randomly permutated matrices are used to generate the statistical distribution and thereby estimate the probability of obtaining an observed association between two matrices. We demonstrate that a considerable error (i.e., 5–6%) may be associated with probability estimates based on such low numbers of permutations. To ensure the stability of the probability estimates (i.e., increase the reliability of the test), we recommend the use of a minimum of 10 000 permutations, and 100 000 permutations if the observed probability approaches a critical significance value (e.g., 0.05).
Reproductive hormone concentrations in faeces during the oestrous cycle and pregnancy in cattle (Bos taurus) and muskoxen (Ovibos moschatus)
Authors: Desaulniers Daniel M. , Goff Alan K. , Betteridge Keith J. , Rowell Janice E. , Flood Peter F.
Published: March 2009

Difficulties associated with blood sampling of wild animals are a deterrent to reproductive research but might be circumvented by the development of noninvasive techniques. Samples of faeces were collected from 4 cyclic and 19 pregnant domestic cows and from 6 female muskoxen during anoestrus, the oestrous cycle, and pregnancy. In cows, the faecal progesterone profile corresponded well with plasma values in cyclic and pregnant animals. Increased concentrations of 15-keto-13,14-dihydroprostaglandin F2α could be detected in bovine faeces during luteolysis using data from a group of animals. A large increase in total oestrogen occurred in both faeces and plasma after the 12th week of pregnancy, confirming that faecal oestrogen levels can be used for pregnancy diagnosis. In the muskox, faecal concentations of total oestrogen and progesterone were correlated with reproductive status, and animals that were anoestrous, oestrous, pregnant, or in the luteal phase of the cycle could be recognized.
The effects of 5-hydroxytryptamine and glutamate on muscle contraction in Hymenolepis diminuta (Cestoda)
Authors: Thompson C. S. , Mettrick D. F.
Published: March 2009

Contractions of the longitudinal musculature from strobilae of the rat tapeworm Hymenolepis diminuta were measured by means of a force transducer. Stretching caused an increase in both the rate and the amplitude of spontaneously occurring contractions while brief stretches could elicit contractions in quiescent preparations. The application of 5-hydroxytryptamine (serotonin) produced variable results; in some preparations there was an increase in the frequency, but not the amplitude, of spontaneous contractions, while in others there was a decrease in both frequency and amplitude of spontaneous contractions. The application of glutamate elicited powerful contractions of the longitudinal muscles in all preparations and restored rhythmic contractions to quiescent preparations.
Antennoseius (Vitzthumia) janus n.sp. (Acari: Ascidae), a mesostigmatic mite exhibiting adult female dimorphism
Authors: Lindquist Evert E. , Walter David Evans
Published: March 2009

All instars of Antennoseius janus n.sp are described. Adult females occur as two distinct morphs, a nondispersing female with granular soft integument, barbed dorsal setae, emarginated opisthonotal shield, and fully developed sternal shield, and a dispersing female with smooth soft integument, nearly smooth dorsal setae, entire opisthonotal shield, and reduced sternal shield. Granular morph females begin egg production within 3 days of mating; however, smooth morph females delay reproduction for many weeks, apparently to disperse. Adult males and immatures have a granular soft integument and barbed setae similar to the granular morph females. Females produced in single animal or low density cultures (less than six individuals per culture) with excess food are granular morphs, whereas in more crowded cultures 5–100% of the maturing females are smooth morphs. This is the first example of adult female dimorphism confirmed experimentally for any family of mites in the entire order Mesostigmata of the Acari. The impact of this phenomenon on taxonomic concepts in the genus Antennoseius is discussed. A key is included, which distinguishes between the genera Anystipalpus Berlese, 1911 and Antennoseius Berlese, 1916, between the subgenera Antennoseius s.str. and Vitzthumia Thor, 1930, and between the seven forms of Vitzthumia currently regarded as species. All instars of A. janus are voracious predators of nematodes and small arthropods. Development from egg to adult takes 9–11 days on a diet of rhabditid nematodes at 23 °C. Generation time for granular morph females is about 14 days. Females require insemination before eggs can be laid, and the sex ratio is about 1 male: 1.3 females.
Some observations on Pseudomenopon pilosum (Amblycera: Menoponidae), the louse vector of Pelecitus fulicaeatrae (Nematoda: Filarioidea) of coots, Fulica americana (Aves: Gruiformes)
Authors: Bartlett Cheryl M. , Anderson R. C.
Published: March 2009

Breeding populations of Pseudomenopon pilosum (Scopoli, 1763) became established on 10 laboratory-reared juvenile American Coots (Fulica americana Gmelin) initially infested with 5 adult male and 5 adult female lice. Eggs of P. pilosum hatched less than 10 days after deposition and the combined duration of the three nymphal instars was 10–20 days. Nymphs and adults occupied all regions of the body. Pseudomenopon pilosum might thus acquire microfilariae of Pelecitus fulicaeatrae (Diesing, 1861) by simply randomly moving to and feeding on the legs where, in infected coots, the skin-inhabiting microfilariae of P. fulicaeatrae are known mainly to occur. Pseudomenopon pilosum occurred on all of 13 adult coots and three 1-week-old coot chicks collected in June in western Canada where P. fulicaeatrae is enzootic. Third-stage larvae of P. fulicaeatrae were found in adult P. pilosum on two of four adult coots harbouring microfilariae, but prevalence in lice was low (5.5% of 18 lice on one coot and 1.1% of 90 on the second) and only one third-stage larva was present in each infected louse. Four other species of lice were present on adult coots but only one other on 1-week-old chicks. Experiments showed that P. pilosum could occur as a straggler on chickens (Gallus gallus (L.)) and Red-necked Grebes (Podiceps grisegena (Boddaert)) although it did not establish on either species.
Oxygen consumption by eggs of the grubby, Myoxocephalus aenaeus, and the longhorn sculpin, Myoxocephalus octodecemspinosus
Authors: Walsh William A. , Lund Jr. William A.
Published: March 2009

Oxygen consumption rates of individual eggs of the grubby, Myoxocephalus aenaeus, and the longhorn sculpin, Myoxocephalus octodecemspinosus, were determined by microrespirometry. Eggs of both species were incubated in temperature – salinity combinations (grubby: in 2, 5, 8 °C at 10, 12.5, 15, 20, 25, 30, 35 parts per thousand (ppt); longhorn sculpin: in 2, 5, 8 °C at 15, 17.5, 20, 25, 30, 35 ppt) to determine the effects of these abiotic factors and development on oxygen consumption rates. Respiration rates of eggs of both species were not affected significantly by constant salinities. Multiple regression analyses demonstrated that the natural logarithms of oxygen uptake rates increased linearly with the temperature – age (in hours after fertilization) interaction and parabolically with age in both species. Oxygen consumption rates increased at hatching. Acute salinity changes did not affect embryonic oxygen consumption by either species. An acute temperature increase, however, elicited increased oxygen uptake by longhorn sculpin embryos (Q10 = 2.56).
Multivariate analysis of the hybrid Phoxinus eos × Phoxinus neogaeus (Pisces: Cyprinidae): reevaluation of univariate analysis
Authors: Joswiak Gerard R. , New John G.
Published: March 2009

Morphological data from two species of minnows, Phoxinus eos and Phoxinus neogaeus, and their hybrids (Pisces: Cyprinidae), previously analyzed by univariate methods, were reanalyzed by multivariate methods. Stepwise discriminant and principal component analyses were conducted on a data set of 14 morphometric measurements from 172 specimens. All of the Phoxinus neogaeus and 87% of both hybrids and Phoxinus eos were correctly classified on functions derived from six discriminating variables. Principal component analysis resulted in the extraction of two factors that explained 90% of the variation in the data set. Mean scores on the first factor were significantly different for P. eos, while on the second factor the mean score for P. neogaeus differed from those of the other two groups. Possible causes of variation in the morphology in the Phoxinus hybrids, from diploidy, tripoloidy, and mosaicism, are discussed.
Precocial male maturation in laboratory-reared populations of chinook salmon, Oncorhynchus tshawytscha
Authors: Taylor Eric B.
Published: March 2009

The incidence of precocial male maturation in yearling chinook salmon, Oncorhynchus tshawytscha, was examined in four laboratory-reared populations. Slim Creek and Bowron River chinook salmon were about 4 weeks older than Harrison and Nanaimo river chinook salmon when sampled (14 vs. 13 months of age), but were also 20–40 g smaller. Approximately 29, 12, 0, and 0% of all males were precocious in Bowron River, Slim Creek, Harrison River, and Nanaimo River chinook salmon, respectively. Precocial male chinook salmon had gonadosomatic indices of about 5–6%, whereas immature salmon from all populations had indices under 1%. Precocial male chinook salmon were more robust bodied than immature salmon; precocial males had deeper bodies, deeper heads, and larger adipose fins. Variation among the study populations in the incidence of precocial male maturation may be related to differences among the populations in migration distance to the sea or in juvenile freshwater rearing life history. The chinook salmon would probably be a productive species with which to study the evolutionary ecology of precocial maturity in Pacific salmonids.
Migratory patterns of sockeye salmon (Oncorhynchus nerka) smolts in the Strait of Georgia, British Columbia, as determined by analysis of parasite assemblages
Authors: Groot C. , Bailey R. E. , Margolis L. , Cooke K.
Published: March 2009

Sockeye salmon smolts from the Fraser River system, migrating northward through the Strait of Georgia towards the Pacific Ocean, follow either an eastern route by immediately travelling northward upon leaving the Fraser River estuary or a western route by first crossing the Strait of Georgia towards Vancouver Island and then moving northward diagonally across the Strait of Georgia to join smolts migrating along the mainland shore. We used variations in parasite assemblages among Fraser River and Lake Washington sockeye smolt stocks and a maximum-likelihood mixture model to estimate the stock composition of the smolts along the two migratory routes. The results showed that most Fraser River sockeye smolts migrate northward via both the eastern and western routes through the Strait of Georgia, indicating that there is no stock specific route selection. Lake Washington smolts were more prevalent along the western route and we suggest that these smolts are transported westward when attempting to cross the Fraser River plume.
White hake, Urophycis tenuis, in the Gulf of Maine: spawning seasonality, habitat use, and growth in young of the year and relationships to the Scotian Shelf population
Authors: Fahay Michael P. , Able Kenneth W.
Published: March 2009

Our interpretation of the pattern of white hake spawning seasonality, habitat use, and growth of young of the year in the Gulf of Maine – Georges Bank area is based on analyses of extensive collections of early life history stages during 1984–1987 and on comparisons with studies conducted in Canadian waters. Eggs or larvae of Urophycis tenuis were not found at any time in the study area, but pelagic juveniles were abundant in May–June and size distributions indicated a shoreward migration with growth. Recruitment to nearshore areas was detected in June–July and the rate of growth for demersal juveniles was calculated to average 1.02 mm/day in the first summer. Spawning of this species during August–September on the Scotian Shelf does not appear to influence the Gulf of Maine population but, instead, appears to involve a separate stock with a different spawning schedule. It is concluded that spawning in continental slope regions south of the Scotian Shelf, Georges Bank, and southern New England during early spring results in recruitment to nearshore areas of the Gulf of Maine and southern New England. This spawning event also provides pelagic juveniles to the Scotian Shelf prior to the onset of local spawning there.
Simulium vittatum (Simuliidae: Diptera), a black fly with a variable instar number
Authors: Colbo M. H.
Published: March 2009

Simulium vittatum is a black fly that normally has 7 larval instars but may undergo several more, with a maximum of 11 instars being recorded in this study. The size increase was relatively constant between individuals for any one instar under similar conditions, but the increase in the first two molts was much greater than observed between late instars. There was little relationship between the relative sizes of certain head capsule measurements in the final instar, indicating the difficulty in determining stable characters for taxonomic separation of closely related simuliid species.
Fine structural evidence for the penetration of the Lyme disease spirochete Borrelia burgdorferi through the gut and salivary tissues of Ixodes dammini
Authors: Zung J. L. , Lewengrub S. , Rudzinska M. A. , Spielman A. , Telford S. R. , Piesman J.
Published: March 2009

The route followed by the Lyme disease spirochete Borrelia burgdorferi as it passes from vector to host has been the subject of controversy over whether the spirochete is transmitted through the saliva of the tick or through regurgitation during feeding. In the event that the spirochete's presence in the salivary tissues is transient we employed a detailed electron microscopic study spanning the period of nymphal attachment to the host to determine whether B. burgdorferi invades the salivary acini and ducts. In addition we examined other tissues of the tick to determine the route and mode of migration. Two different groups of nymphs were used in this study. After feeding, spirochetes were found in both groups in the gut lumen, epithelium, and within the salivary glands and ducts. Borrelia is able to pass both inter- and intra-cellularly through these tissues. In one group of unfed nymphs Borrelia was limited to the gut lumen, whereas the second group demonstrated a disseminated infection. This difference might be due to transovarial transmission, the geographic origin, and (or) age of the ticks. The finding of Borrelia within the salivary glands and ducts provides strong evidence for the salivary transmission of the Lyme disease spirochete.
Seasonal patterns in physiology and nutrition of black bears in Great Dismal Swamp, Virginia – North Carolina
Authors: Hellgren Eric C. , Vaughan Michael R. , Kirkpatrick Roy L.
Published: March 2009

Diet quality, condition indices, and blood chemistry characteristics were determined for a black bear (Ursus americanus) population in the Great Dismal Swamp on the Atlantic Coastal Plain. Blood samples from 122 captures of 99 bears were analyzed. Seasonal shifts in diet composition were similar to previously reported findings for black bear food habits in the southeastern United States. Three major levels of diet quality were observed in terms of crude fiber, fat, and protein. Spring diets were high in protein but moderate in crude fiber. Condition indices (body weight, length/weight ratios) peaked in spring and late fall and were low during summer. Several blood characteristics (e.g., total protein, albumin, hematocrit, hemoglobin, and red blood cells) showed a similar annual rhythm (P < 0.01) for both sexes. Serum creatinine concentrations also varied seasonally (P < 0.001), with a peak during denning and high levels in spring and late fall, perhaps resulting from transition from and to hibernation. Urea/creatinine ratio was not a good indicator of the hibernating state, as 39 of 120 (32.5%) trapped bears had urea/creatinine ratios ≤ 10. Creatinine and total protein were the best indicators of the hibernating state. Albumin, hematocrit, hemoglobin, and red blood cells were the best indicators of condition during active stages, as correlations of condition indices and blood variables indicated significant (P < 0.1) associations between body condition and albumin, hematocrit, hemoglobin, and red blood cells. Nine blood variables varied with age (P < 0.1). Multivariate analysis of variance and discriminant function analysis using blood variables failed to reject the hypothesis that bears cycle through four metabolic stages throughout the year. Our results showed that metabolic shifts were tied to concomitant seasonal changes in diet quality, diet composition, and body condition. Comparison of our work with other published data on bear biology suggests that seasonal changes in bear physiology may be due partly to an endogenous rhythm.
A revision of Entobdella Blainville (Monogenea: Capsalidae) with particular reference to E. hippoglossi and E. squamula: the use of ratios in taxonomy and key to species
Authors: Klassen G. J. , Beverley-Burton M. , Locke A.
Published: March 2009

Morphologic and morphometric characters for 14 Entobdella species were reviewed. Entobdella brattstroemi, E. curvunca, E. rosaceus, E. squamula, and E. steingroeveri were found to be morphologically indistinguishable from E. hippoglossi, the type species, and are declared synonyms. A redescription of E. hippoglossi is presented. Allometry and the use of ratios to differentiate species are discussed. The nine valid Entobdella spp. belong to two monophyletic subgroups: the "hippoglossi" group (E. hippoglossi, E. soleae, and E. pugetensis) and the "diadema" group (E. diadema, E. bumpusii, E. corona, E. guberleti, E. apiocolpos, and E. australis). A key to species is included.
Morphological variation of Elliptio complanata (Bivalvia: Unionidae) in differing sediments of soft-water lakes exposed to acidic deposition
Authors: Hinch Scott G. , Kelly Laura J. , Green Roger H.
Published: March 2009

Clam shell morphology was related to lake water chemistry and sediment properties for Elliptio complanata from 40 south central Ontario lakes. Principal component analyses described the major trends in the environmental data. Relationships between shell morphology and the environmental trends were ascertained through a canonical correlation analysis. Thicker shells were related to increasing alkalinity, conductivity, and pH, suggesting that shell formation is favoured in well-buffered habitats that are not affected by acidic deposition. We also determined that narrow shells were related to coarse sediment in deeper water. This pattern of variation in shell morphology may be adaptive because streamlined shells would better enable clams to maintain their position in turbulent habitats. The water chemistry and sediment property correlates with shell morphology were independent of each other. Any attempt to use unionid shells as long-term indicators of changes in environmental water chemistry must be preceded by a consideration of other habitat variables such as water turbulence, sediment type, and depth.
Underwater vocalizations of the bearded seal (Erignathus barbatus)
Authors: Cleator Holly J. , Stirling Ian , Smith T. G.
Published: March 2009

The underwater vocalizations of bearded seals (Erignathus barbatus) were recorded between March and June in 1979, 1982, and 1983 at six sites in the Arctic. In total, 970 trills were measured for temporal and spectral characteristics and then classified as one of six types. Trills were narrow in bandwidth and frequency modulated. The repertoires of vocalizing bearded seals varied amongst the six recording sites. Between-site differences in temporal and spectral features, call use, and sequential organization were measured. The results suggest that bearded seals may be relatively sedentary and that geographically different vocal repertoires may be characteristic of discrete breeding stocks. A prominent daily cycle in rate of calling during April and May was found at two sites; rate of calling was higher during the early morning hours (i.e., 03:00–04:00 sun time) than at other times of the day. No distinct temporal cycle occurred during late May and early June. Rate of calling appeared to be negatively correlated with pattern of haul out. In simultaneous recordings, a few (13 of 156) bearded seal trills were recorded up to a distance of 25 km underwater.
Sibling cannibalism in noncannibal morph Ambystoma tigrinum larvae and its correlation with high growth rates and early metamorphosis
Authors: Lannoo Michael J. , Lowcock Leslie , Bogart James P.
Published: March 2009

We describe here, for the first time, the existence of an Ambystoma tigrinum tigrinum larval morph characterized by fast growth rates and early metamorphosis and triggered by cannibalism. This new morph does not have the anatomical specializations of true A. tigrinum cannibal morphs, i.e., enlarged vomerine teeth and a wider head described previously by several workers. Functionally, however, this new morph and true cannibal morphs achieve the same end; high growth rates and early metamorphosis may facilitate survival in individuals inhabiting temporary and unpredictable wetlands.