bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen consumption, thermoregulation, and the effect of fur oiling and washing on the sea otter, Enhydra lutris
Authors: Costa Daniel P. , Kooyman Gerald L.
Published: August 2008

The relative importance of a water-repellent fur was assessed by changes in oxygen consumption [Formula: see text] and in body and subcutaneous temperatures before and after oiling and washing in 15 °C water. In addition, changes in posture and [Formula: see text] in five sea otters were measured while immersed in water from 5 to 30 °C. Measurements were made in an enclosed water bath with Vo2 determined by open-flow respirometry. Core body and subcutaneous temperatures were telemetered. Resting [Formula: see text] was 11.7 mL O2∙kg−1∙min−1 and did not significantly increase with decreasing temperature. Average and active [Formula: see text] increased with decreasing temperature. Average [Formula: see text] (16.0 mL O2∙kg−1∙min−1) increased 41% (22.0 mL O2∙kg−1∙min−1) after oiling 20% of the total fur surface and more than doubled (32.6 mL O2∙kg−1∙min−1) after washing. Oiling and washing reduced the fur's insulating quality. The result was an energetic liability, since the average maintenance [Formula: see text] doubled in 15 °C water; this temperature is above typical water temperatures for this species, which range from 0 °C (Alaska) to 12 °C (California). Average [Formula: see text] returned to control levels after a minimum of 8 days.
Rodlet cells in the gill and intestine of Catostomus commersoni and Perca flavescens: a comparison of their light and electron microscopic cytochemistry with that of mucous and granular cells
Authors: Leino Richard L.
Published: August 2008

Rodlet, mucous, and granular cells from the gills and intestines of two teleosts, Catostomus commersoni and Perca flavescens, were examined using light and electron microscopic cytochemical methods. The peripheral substance in the bipartite granules of rodlet cells was positive for carbohydrates (periodic acid – Schiff (PAS)) and proteins (e.g., coupled tetrazonium) but was uncolored by stains for lipid (Sudan black), nucleic acids (e.g., gallocyanin), and chemical groups of certain carbohydrates (e.g., alcian blue (AB), pH 1.0). The core of the granules showed positive protein but no carbohydrate, nucleic acid, or lipid staining. Electron microscopy revealed granules with (1) a protease resistant, periodic acid – silver methenamine positive periphery probably rich in glycoprotein and (2) a protease-digestible, silver methenamine negative core, perhaps of relatively pure protein. The granules were resistant to ribonuclease digestion. Mucous cells generally stained more strongly than rodlet cells for carbohydrate (PAS, AB, pH 2.5 and 1.0; periodic acid – silver methenamine) and had a greater range of staining intensities indicating a more variable carbohydrate component. Protein and lipid stains left mucus granules uncolored. Granular cells of P. flavescens were moderately PAS positive and stained strongly for protein. Granular cells of C. commersoni were strongly PAS positive and stained moderately for protein; their granules exhibited periodic acid – silver methenamine positive rims and unstained central "nucleoids."
Ectoparasites and other associates of some insectivores and rodents from New Brunswick
Authors: Whitaker Jr John O. , French Thomas W.
Published: August 2008

Ectoparasites and other associates were examined from seven species of insectivores and nine species of rodents from Mount Carleton Provincial Park, New Brunswick. The most abundant forms found were (at least 2.0 per host individual) the following: Orycteroxenus soricis and Amorphacarus hengererorum on Sorex cinereus and on Sorex (Microsorex) hoyi; A. hengererorum and O. soricis on Sorex fumeus; O. soricis, Miyatrombicula esoensis, and Ixodes angustus on Sorex gaspensis; O. soricis, I. angustus, Pygmephorus horridus, and Protomyobia americana on Blarina brevicauda; M. esoensis, Protomyobia claparedei, and Glycyphagus hypudaei on Sorex palustris; Orycteroxenus canadensis, O. soricis, P. horridus, G. hypudaei, Ctenophthalmus pseudagyrtes, and Haemogamasus ambulans on Condylura cristata. More abundant ectoparasites of the rodents were as follows: G. hypudaei, Listrophorus mexicanus, M. esoensis, Neotrombicula harperi, and Radfordia lemnina on Clethrionomys gapperi; G. hypudaei, L. mexicanus, M. esoensis, N. harperi, and Laelaps kochi on Microtus chrotorrhinus; L. mexicanus, G. hypudaei, Radfordia hylandi, Laelaps alaskensis, M. esoensis, Polyplax alaskensis, L. kochi, N. harperi, and Myocoptes j. japonensis on Microtus pennsylvanicus; Listrophorus synaptomys, Hoplopleura acanthopus, L. alaskensis, G. hypudaei, M. esoensis, I. angustus, R. hylandi, and N. harperi on Synaptomys cooperi; all of these except the last one on Synaptomys borealis; M. esoensis on Peromyscus maniculatus; Dermacarus newyorkensis on Zapus hudsonius; D. newyorkensis, N. harperi, Radfordia ewingi, and G. hypudaei on Napaeozapus insignis; Dermacarus hylandi, N. harperi, Megabothris acerbus, and M. esoensis on Tamias striatus.
Environmental heterogeneity and life history variability in the freshwater clams, Pisidium variabile (Prime) and Pisidium compressum (Prime) (Bivalvia: Pisidiidae)
Authors: Way Carl M. , Wissing Thomas E.
Published: August 2008

The pisidiid clams, Pisidium variabile (Prime) and Pisidium compressum (Prime), from permanent ponds in southwestern Ohio are iteroparous, bivoltine, and have approximate longevities of 1 year. Intrapopulation differences in life history characteristics are discussed in relation to environmental heterogeneity. For the P. variabile population, only age at first reproduction (110 and 226 days for the spring and fall generations, respectively) is different for both annual generations. This is due to differences in environmental variables (temperature, dissolved oxygen levels, food availability) which set physiological limits on growth, reproduction, and maintenance functions. The spring and fall generations of P. compressum show differences in several life history characteristics: age at first reproductive (122 and 270 days, respectively), net reproductive rate (8.7 and 3.7, respectively), r (0.005 and 0.003, respectively), and the number of broods per year (2 and 1, respectively). The results of this study tend to question the validity of using current theories (e.g, r- and K-selection, bet-hedging) which attempt to predict the set of demographic characteristics that should be found in populations under varying environmental circumstances.
A cytological description of 10 taxa in Metacnephia (Diptera: Simuliidae)
Authors: Procunier William S.
Published: August 2008

Cytological descriptions and phylogenetic relationships are presented for 10 blackfly taxa in Metacnephia. These descriptions are given in terms of standard polytene chromosome maps based on M. pallipes. All members are male chiasmate and differ from related Cnephia by a whole arm interchange between chromosomes I and II. Sex chromosome differentiation varies from undefined changes resulting in a short, nonpairing centromeric segment in X0Y1 males of M. amphora to a complex system in M. borealis. The latter system involves Y chromosome differentiation by associated inversions and sex linkage of the nucleolar organizer (NO). Metacnephia borealis exhibits a sex bias in NO expression with excess expression in females and an apparent conversion phenomenon which dosage compensates males. The closest members of Metacnephia differ only in their sex chromosomes and share floating inversions; more distant taxa differ by fixed inversions as well as sex chromosomes. IIIS-1, IIIS-2, and IIIS-3 may be polymorphic, sex linked, or fixed in different species of the group. Nonhomology of sex chromosomes of different species, association of the sex locus and NO, and presence of an identical supernumerary block on nonhomologous chromosomes indicate a mobility phenomenon for certain loci.
A cytological study of species in Cnephia s. str. (Diptera: Simuliidae)
Authors: Procunier William S.
Published: August 2008

Cytological descriptions and phylogenetic relationships are presented for the genus Cnephia s. str. All members are male achiasmate. Cnephia lapponica is unique in that its basic chromosome complement is reduced from n = 3 to n = 2 metacentrics as a result of a fusion of chromosomes II and III. Sex chromosome differentiation varies from nonobservable in C. ornithophilia and C. eremites through C. pecuarum in which the standard and IS-5 sequences are distributed differentially over X and Y chromosomes, to the polytypic system of C. lapponica in which the X chromosome is fixed for expression of the nucleolar organizer (NO) and the Y chromosome for nonexpression. Further, in a Norwegian population of C. lapponica, males are additionally interchange heterozygotes. Thus, a multiple sex chromosome system exists in which all the chromosomes are sex chromosomes. Closest members occur sympatrically and differ by sex chromosomes and at least one fixed inversion; more distant taxa differ by a number of fixed inversions as well as sex chromosomes. The identical bands 17B and 24C, which appear in a thin or enhanced form, are polymorphic, sex-linked, fixed, or lost in different members of the group. This study supports a model for sympatric speciation.
The interdependence of B chromosomes, nucleolar organizer expression, and larval development in the blackfly species Cnephia dacotensis and Cnephia ornithophilia (Diptera: Simuliidae)
Authors: Procunier William S.
Published: August 2008

A primary relationship is found between nucleolar organizer (NO) expression (puffing) of the A complement and numbers of B chromosomes in Cnephia dacotensis, such that a high incidence of B's is associated with nonexpression of the NO independent of sampling time and larval size. NO expression can be categorized into three zygote classes: + +, + −, and − −, where + indicates puffing of one constituent and − indicates little or no puffing. The + + types generally mature earlier than the + − and − − types. These observations suggest that development rates are a function of NO expression: − − types do not mature at all unless they have B's and (or) secondary nucleoli. Population comparisons confirm the prediction that as the frequency of individuals with one or more B's decreases, the frequency of individuals with expressed constituents increases. A sex bias in NO expression exists with more expression in females. Additional plasticity is conferred to the system through an apparent conversion phenomenon which reduces X+X+ expression in females and dosage compensates X−Y− males. Both of these effects are B-chromosome dependent and are lost in zero B populations. It is proposed that B–A NO interactions constitute a system for more efficient rRNA production by optimizing synthesis between the sexes. This system may account for the wider range and occupation of more diversified habitats of C. dacotensis than for other members of the group. A similar but less dynamic role is proposed for the effects of B chromosomes in C. ornithophilia.
Alternation calling and spacing patterns in the field cricket Acanthogryllus fortipes (Orthoptera; Gryllidae)
Authors: Cade William H. , Otte Daniel
Published: August 2008

Field observations and experiments in the Republic of South Africa demonstrated that burrowing male field crickets, Acanthogryllus fortipes, call in alternation by singing during the interval of silence in a neighbour's song. Alternating males had a chirp rate which was 30 to 60% that of nonaltrnating males. Rapidly singing and nonalternating males responded to taped playbacks of conspecific song by reducing their chirp rate to match that of a loudspeaker. Alternation calling is observed after sunset. Males do not alternate when they begin singing during the day. Nearest neighbour analyses of calling males and of cricket burrows show that calling males are spatially aggregated, but that burrows or potential signaling sites are not localized. In playback experiments where the loudspeaker to male distance was repeatedly reduced, males called at distances comparable to those separating actual males. Males became silent, however, when the loudspeaker was moved inside of the minimum intermale distance observed in the field. Spacing patterns are more compact in A. fortipes, a deep burrowing species, than in other gryllines, and A. fortipes is the only cricket species in which alternation of male calls has been demonstrated experimentally.
On the dispersion, population structure, and life history of a basommatophoran snail, Helisoma trivolvis, in central Alberta
Authors: Morris J. R. , Boag D. A.
Published: August 2008

We studied the dispersion, population structure, and life history of a northern population of Helisoma trivolvis inhabiting an artificial pond in central Alberta in 1968 and 1969. In both years, snails were concentrated from May to October within the first 6 m from shore (150 cm in depth). In spring the number of overwintered snails rose from 21∙m−2 in 1968 to 42∙m−2 in 1969, but juvenile recruitment fell from 160∙m−2 in 1968 to 0∙m−2 in 1969. Based on the number of varices, some individuals survived up to five summers. Varix counts on samples of empty shells suggested that on average about 65% of the adult population was 1 year old with proportionately fewer in each older age category. Maturation among 1-year-old snails appeared to require growth to more than 9.0 mm maximum diameter. Although the diameter attained by young snails in their first summer ranged from 8 to 16 mm, none was recorded spawning before their second summer. Survivors spawned in each succeeding summer unless rendered infertile by trematode infections. Peak spawning occurred in late May. Mean number of eggs per egg mass varied between years from 30 to 37. Juveniles appeared in early July and reached peak numbers by mid-July. Survival of young snails changed dramatically between years. The role of iteroparity as an adaptive strategy of this species is discussed in the context of fluctuating productivity.
Seasonal changes in weight gain, growth hormone, and thyroid hormones in intact and castrated male moose (Alces alces alces)
Authors: Ryg Morten
Published: August 2008

To elucidate possible endocrine mechanisms in the control of cyclic weight gain in moose, serum concentrations of growth hormone (GH), thyroxine (T4), and triiodothyronine (T3) were recorded during the year in two intact and one castrated male moose. Changes in the levels of these hormones were compared with changes in weight gain. Growth hormone often increased to peak values in April or May, but was generally low throughout the period of greatest weight gain. Thyroid hormone levels increased in spring and decreased in autumn, corresponding to onset and cessation of rapid weight gain. Changes in triiodothyronine levels may have been secondary to changes in food intake.
Copulatory behaviour of Richardson's ground squirrels (Spermophilus richardsonii) in the wild
Authors: Davis Lloyd S.
Published: August 2008

In this paper I give the first authenticated account of copulation occurring above ground in Richardson's ground squirrels. Copulation occurs in a dorso-ventral position with both animals lying on their sides, and is characterized by a high degree of agonism between the pair.
Hip glands in a field population of Microtus pennsylvanicus
Authors: Boonstra R. , Youson J. H.
Published: August 2008

Hip glands are reported to be absent in Microtus pennsylvanicus. This paper presents histological evidence that they are present in field populations of this species in southern Ontario. Well-developed hip glands were found in 11 breeding males. No consistent relationship was found between the degree of development of the glands and breeding status in five females. We suggest that histological examination will reveal the presence of hip glands in other populations of this species as well.
Response of Microtus pennsylvanicus to multiple-capture traps
Authors: Mihok Steve , Boonstra Rudy , Rodd F. Helen , Schwartz Bill
Published: August 2008

Microtus pennsylvanicus was livetrapped on demographic grids in Ontario and Manitoba to determine the efficiency of Longworth and one-way door multiple-capture traps. In paired-choice field trials, multiple-capture traps caught far fewer voles than did Longworth traps. Sand-tracking and a flagging system indicated that voles rarely lifted the one-way door of the multiple-capture trap, although they often approached the traps and began to enter the one-way door.
Studies of animal color vision: comments on some important theoretical considerations
Authors: Hawryshyn Craig W.
Published: August 2008

Eliminating brightness as a discriminatory cue is unquestionably the most important factor in animal color vision studies. Accurate descriptions of any species' color vision depends on, first, a determination of spectral sensitivity (electrophysiologically or psychophysically) which can then be used to establish a brightness match between the comparison stimuli and, second, tests of wavelength discrimination. The use of innate responses to investigate animal color vision introduces variables which are not characteristically visual. Since these innate behaviors involve neural mechanisms other than the visual system, they tend to distort the normal characteristics of the species' color vision.
Experimental studies on acarine predator–prey interactions: distribution of search effort and predation rates of a predator population in a patchy environment (Acarina: Phytoseiidae)
Authors: Eveleigh Eldon S. , Chant D. A.
Published: August 2008

The responses of a population of adult female Phytoseiulus persimilis and Amblyseius degenerans in a patchy environment were examined for 2 days in the laboratory. Progressive prey exploitation caused continuous redistribution of P. persimilis among the patches of prey, and although more individuals tended to occupy the highest density patch than other patches, there was an indication that "interference" limited the tendency of the predators to aggregate in this patch. In contrast, there was little redistribution of A. degenerans among the patches despite extensive prey exploitation. This species did not show an aggregative response nor was there any "interference" between the predators. The predation rates of P. persimilis declined with time and their foraging behaviour was not optimal on either day. In contrast, A. degenerans completely exploited the prey in all patches. The feeding and searching strategies of the two predator species are discussed in terms of their respective food habits. The implications of the characteristics of the predators for biological control are also briefly discussed.
New species of the gutless marine genus Inanidrilus (Oligochaeta, Tubificidae) from the Gulf of Mexico and Barbados
Authors: Erséus Christer , Baker H. R.
Published: August 2008

The definition of Inanidrilus Erséus, 1979 (subfamily Phallodrilinae) is emended to include Inanidrilus mexicanus sp. nov. from the eastern part of the Gulf of Mexico, and Inanidrilus falcifer sp. nov. from coral reefs at Barbados, West Indies. The two new species differ from I. bulbosus Érséus, 1979 by their possession of paired spermathecae and from each other in the morphology of their spermathecae, atria, and penial setae.
Reproductive tactics of Ameiva ameiva (Lacertilia: Teiidae) in a seasonally fluctuating tropical habitat
Authors: Vitt Laurie J.
Published: August 2008

The reproductive ecology of Ameiva ameiva was studied for 12 months in a caatinga habitat of northeast Brazil. Even though rainfall was seasonal, the female reproductive cycle was not associated with this seasonality. Females reproduced year-round, with peak reproductive periods during August–October and January–February. Clutch size ranged from one to nine and was correlated to female size but egg size was constant. Males showed evidence of reproductive activity throughout the year. Fat body mass of males and females varied greatly among individuals. There was no association between fat storage and wet–dry seasonality. In females, fat body mass tended to decrease during peak reproductive periods. Most striking was the observation that 97.8% of all adult Ameiva possessed enlarged fat bodies, suggesting that resource periods low enough to affect reproduction did not exist during 1977–1978. The reproductive tactics of Ameiva were similar to those of other tropical macroteiids, regardless of their distribution, but very different than reproductive tactics of sympatric iguanid lizards. Compared with iguanid lizards, resources may be less limiting for macroteiids because their widely foraging behavior for prey acquisition may allow them to find rich patches of resources which would be unavailable to habitat specific sit-and-wait foragers, like most iguanid lizards.
Methyl mercury induced visual deficits in rainbow trout
Authors: Hawryshyn Craig W. , Mackay William C. , Nilsson Thomy H.
Published: August 2008

Scotopic spectral sensitivity of 15 rainbow trout was determined using a two-choice, operant-conditioning task. Maximum sensitivity occurred at 525 nm and generally declined at longer and shorter wavelengths with evidence of a "shoulder" at 600–650 nm. Fifteen days after injection with either saline control (n = 4) or 4.6–6.2 mg of methyl mercury chloride per kilogram of body weight (n = 9); measurements of response latency and trials to criterion revealed that methyl mercury (MEHG) did not affect memory or motor performance. MEHG did produce significant spectrally uniform decrements in visual sensitivity. These results suggest that MEHG impaired both the scotopic and photopic mechanisms of MEHG-treated rainbow trout.
Digestive proteinases of Sitophilus weevils (Coleoptera: Curculionidae) and their response to inhibitors from wheat and corn flour
Authors: Baker J. E.
Published: August 2008

Hydrolysis of two general proteinase substrates and seven substrates specific for trypsin-like and chymotrypsin-like enzymes, aminopeptidases, and carboxypeptidases was demonstrated by homogenates of alimentary systems of larvae and adults of Sitophilus oryzae (L.), S. zeamais Motchulsky, and S. granarius (L.). Endopeptidase activity was very low in all species, whereas aminopeptidases and carboxypeptidases were relatively active. Hydrolysis of α-N-benzoyl-DL-arginine-p-nitroanilide (BApNA) by larvae and adults of S. granarius was due to a single enzyme, inhibited by N-α-tosyl-L-lysinechloromethyl ketone (TLCK) and soybean trypsin inhibitor, and with a relative mobility of 0.49 on an anionic polyacrylamide gel system. This enzyme was not detected in S. oryzae or S. zeamais. Aminopeptidases (hydrolysis of L-leucine-p-nitroanilide) were inhibited by 1, 10-phenanthroline, Cd2+, and Hg2+, and existed in two major and two to three minor isozymes in each species. Water extracts of wheat and corn flour inhibited the BApNA enzyme from S. granarius but had no effect upon the aminopeptidases and carboxypeptidases (hydrolysis of N-carbobenzoxy-L-valyl-L-leucine).
The behaviour of Urocleidus adspectus Mueller, 1936 (Monogenea) on the gills of Perca flavescens
Authors: Cone D. K. , Burt M. D. B.
Published: August 2008

This study examines the behaviour of Urocleidus adspectus on the gills of yellow perch (Perca flavescens). The adult worm is found firmly attached to the gills of the host with the haptor fitted snugly into an interlamellar space and with four large hamuli and 14 small marginal hooks impaled into the adjacent epithelium. The forebody of the worm is almost always directed downstream toward the tip of the primary lamella. The worm is a tissue feeder and the reach and flexibility of the forebody allow efficient grazing around any one site of attachment. Worms can graze farther by moving to a new site of attachment. This involves a leechlike movement in which the haptor and the head are alternately used as the organ of attachment. The movement is brief (3 s or less) and, most likely in response to the threat of dislodgment, only single relocations are made at any one time. The worm almost always comes to lie in the preferred adhesive attitude no matter what the direction of travel under natural conditions. However, under experimental conditions in which there was no water flow, the position was occasionally reversed.
The annual cycle of sexual reproduction in the sea anemone Metridium senile
Authors: Bucklin Ann
Published: August 2008

The seasonal timing of sexual reproduction of Metridium senile, a sea anemone occurring intertidally and subtidally on the coast from central California to Alaska, was studied at Bodega Bay, Sonoma County, California. Individuals reproduce asexually by the regeneration of fragments torn from the pedal disc and populations consist of clones of various size and extent. Histological examination of specimens collected monthly from December 1976 to November 1979 demonstrated an annual cycle of sexual reproduction. In females, oocyte size and relative gonad size increased steadily from fall to late summer and peaked in August of each year. In males, recording the most advanced stage of spermatogenesis in each individual revealed a distinct annual cycle of gonadal maturation in 1977, but the seasonal pattern was obscured in 1978 and 1979 by the early appearance and prolonged persistence of sperm. Gonadal maturation was asynchronous among three populations studied (one harbor float and two intertidal), but the spawning of males and females in all three populations occurred between the September and October collections in each year.
Revision of the milliped genus Auturus (Polydesmida: Platyrhacidae)
Authors: Shelley Rowland M.
Published: August 2008

The milliped genus Auturus consists of the valid species evides (Bollman), mcclurkini Causey, louisianus (Chamberlin), and erythropygos (Brandt), the last two of which are divided into two subspecies each. The other four nominal species are relegated to appropriate synonymies. Auturus evides, louisianus, and mcclurkini occur in the central United States, along the Mississippi River from central Minnesota to the Gulf of Mexico. Auturus erythropygos is widely allopatric and occurs in the southeastern United States from northern North Carolina to northern Florida. The four species are anatomically similar, and all occur exclusively in association with moist, decaying hardwood logs or stumps. They can be distinguished only by details of the male gonopods, particularly the orientation of the terminal calyx and the position of the solenomerite within the calyx. Auturus evides, louisianus, and erythropygos are phenotypically similar and appear to be closely related; mcclurkini, however, possesses a number of unique characters and represents a separate line of descent. The genus Illiniums, recently synonymized with Auturus, is revived on the basis of published illustrations of its type species, I. beattyi Shear.
Foods selected by blue grouse (Dendragapus obscurus fuliginosus)
Authors: King R. Dennis , Bendell James F.
Published: August 2008

The spring and summer diet was determined from 811 blue grouse crops collected from 1957 through 1966 near the town of Campbell River on Vancouver Island. Main foods eaten were conifer needles, broad-leaved vegetation, flowers, fruits, and invertebrates. More than 80% of the plant diet was from nine species. Most foods were selected and selection varied with season, sex, and age. In the spring, females apparently ate more broad-leaved plants than did males, and chicks up to approximately 3 weeks of age fed largely on invertebrates, mainly ants (Formicidae). We attempt to explain selection by relating known nutrients in plants and animals to their use as food. Selection may be partly explained by availability, nutrients, and the nutritional requirements of grouse. Nutrients apparently selected most frequently were ash and nitrogen. The diet of females in May and June seemed richer than that of males in ash, nitrogen, and magnesium. In June, chicks had a diet likely higher in nitrogen, phosphorus, and potassium but lower in carbohydrate, fat, and calcium when compared with adults. The diet of blue grouse compared with that recommended for some other grouse was possibly deficient in ash, phosphorus, and calcium. We postulate food on the summer range might limit populations of blue grouse by the amount of nitrogen and minerals, especially calcium, available to hens in spring and by a range of nutrients available to very young chicks.
Mating call characteristics of hybrid toads (Bufo americanus × B. fowleri) at Long Point, Ontario
Authors: Green David M.
Published: August 2008

The mating calls of the toads Bufo americanus, B. fowled, and their natural hybrids were recorded in May 1981 at Long Point, Ontario, on the northern shore of Lake Erie. The calls of the two species differed substantially in pulse rate and call duration but much less so in terms of dominant frequency. The numbers of pulses per call were not significantly different. Calls of hybrids were intermediate in character. Values for pulse rate, call duration, and dominant frequency agreed with those previously described. The relationship between pulse rate and call duration is hyperbolic as pulse number appears to be relatively constant. The differences in the calls of B. americanus and B. fowled appear to be fundamentally due to mechanical properties of the pulse modulating apparatus of the larynx. The characteristics of the calls of the hybrids may be due to intermediate morphology of the laryngeal cartilages that modulate the pulses of a call.
Mycophagy of red-backed voles in Oregon and Washington
Authors: Ure Douglas C. , Maser Chris
Published: August 2008

We analyzed stomach contents from two subspecies of Clethrionomys californicus and three subspecies of C. gapperi from coniferous forests of Oregon and western Washington. Seasonal diets were determined for each subspecies of C. californicus. Major foods eaten were the fruiting bodies of hypogeous ectomycorrhizal fungi, predominantly Gasteromycetes, and fruticose lichens, regardless of season. Fungus consumption partially depended on availability. When fungi became scarce, lichens were substituted. Other foods were important only during winter in Cascade Range. Clethrionomys gapperi from Washington consumed large quantities of conifer seed and green plant parts in midautumn. These materials were a small part of the diets of Oregon red-backed voles in midautumn, but this may relate to localized small seed crops. Dependence on ectomycorrhizal fungi by western red-backed voles probably accounts for the latter's disappearance from deforested sites.
Female sociality in the common eider duck during brood rearing
Authors: Schmutz J. K. , Robertson R. J. , Cooke F.
Published: August 2008

This study investigates the potential adaptive significance of the behavior of female common eider ducks (Somateria mollissima) which have no young of their own ("aunts") but accompany other females and young. "Aunts" exhibited ambivalent aggression and protection toward ducklings. There was no evidence that the presence of "aunts" enhanced the survival of the ducklings they accompanied. Both females which had their clutch removed and females which had not laid eggs behaved as "aunts." The level of circulating prolactin hormone in "aunts" was lower than in incubating females and similar to the basal level of males. We therefore rejected the hypothesis that maternal care was misdirected during hormonal adjustment from breeding to nonbreeding. We suggest that "aunts" which have lost a clutch or brood, spend some time feeding away from the colony, and then return to the nesting grounds after replenishing their nutrient reserves. Upon returning, "aunts" may select sites for nesting in future years. During this time, they are temporarily attracted to broods. We propose that "aunts" flock and fend off predators during an attack in an attempt to seek safety in a flock rather than to protect ducklings of other females.
Black flies (Diptera: Simuliidae) from Hardwicke Island, British Columbia
Authors: Mahrt Jerome L.
Published: August 2008

Nineteen species of immature simuliids (Diptera: Simuliidae) were collected from streams on Hardwicke Island in the Johnstone Straits of British Columbia. These species were Simulium aureum Fries, S. canadense Hearle, S. decorum Walker, S. hunteri Malloch, S. tuberosum Lundström complex, S. venustum Say – verecundum, Stone and Jamnback complex, Prosimulium dicum Dyar and Shannon, P. esselbaughi Sommerman, P. formosum Shewell, P. travisi Stone, Simulium anatinum Wood, S. bafftnense Twinn group, S. bicorne Dorogostajskij, Rubtzov and Vlasenko complex, S. gouldingi Stone, S. piperi Dyar and Shannon, S. pugetense (Dyar and Shannon), S. vernum Macquart complex, Prosimulium doveri Sommerman, and Stegopterna sp. Enderlein. The last nine species have not been reported previously from British Columbia. Species composition, succession, and seasonal abundance of larvae and pupae were determined from April to August of 1980 and 1981. Simulium venustum–verecundum complex and S. hunteri were the most abundant species in 1980, while S. hunteri and S. vernum complex were most abundant in 1981. Black fly productivity was greatly reduced in 1981.
Seasonal effects of photoperiod and temperature on the ovary of the three-spined stickleback, Gasterosteus aculeatus L.
Authors: Borg Bertil , Veen Theo Van
Published: August 2008

Seasonal effects of photoperiod (16 h light (L): 8 h dark (D) and 8 h L: 16 h D) and temperature (18 and 8–9 °C) were studied on the ovary of the three-spined stickleback at 2-month intervals throughout the year. At the higher temperature, advanced oocyte development took place only in 16 h L: 8 h D in November and January, while in March and May an increasing proportion of the females matured also in 8 h L: 16 h D. Many fish in 8 h L: 16 h D, 18 °C, in November–May showed a marked regression of the ovaries and large numbers of atretic eggs. At the lower temperature in November–May the ovaries developed slowly, or showed little change compared with the initial controls. No consistent effect of photoperiod was found at the lower temperature in any season. The ovaries regressed in July, fastest at the higher temperature. No photoperiodic effects could, however, be detected. At the commencement of the September experiment the ovaries were in a regressed state and no advanced oocyte development was reached in any group.
The importance of sampling and sorting techniques in the elucidation of the life cycle of Zapada columbiana (Nemouridae: Plecoptera)
Authors: Mutch R. A. , Pritchard G.
Published: August 2008

The life cycle of Zapada columbiana (Claassen) was shown to be of 2 years duration at three sites in Alberta, Canada, where the species was previously said to be univoltine. The erroneous conclusion of previous investigators was attributed primarily to the use of nets with too large a mesh size. However other factors such as sorting without magnification, inability to recognize young Z. columbiana, and erroneous assumptions regarding egg incubation times may also have contributed. It is suggested that the temperature regimes of the streams in the Alberta Rocky Mountains are such that Zapada columbiana cannot complete its life cycle in 1 year.
A versatile thermal gradient apparatus for studying thermal biology of snakes in the laboratory
Authors: Gregory Patrick T. , Douwens Robert J. , McIntosh A. G. Duncan
Published: August 2008

We present a design for a thermal gradient apparatus which allows long-term maintenance of temperature gradients which can be varied in position and in range from extremely wide to extremely narrow. The apparatus can also be used simply as a series of controlled-temperature chambers. A high degree of control of temperature along the gradient is possible. Preliminary temperature-selection experiments with garter snakes yielded results consistent with interspecific differences observed in the field.
Shallow-water propagation of frequencies in aquatic insect sounds
Authors: Aiken Ronald B.
Published: August 2008

The possible use of sounds produced by aquatic insects over distances similar to those of terrestrial insects was examined. Pure tones, spanning the range of those found in aquatic insect sounds, were broadcast in shallow water. At intensities representative of those produced by aquatic insects, all frequencies were usually attentuated within 1 m and their function as acoustic beacons must be considered within such limits.
An immunocytochemical study of regulatory peptides in the amphibian gastrointestinal tract
Authors: Buchan A. M. J.
Published: August 2008

Samples from the gastrointestinal tract of two urodele and eight anuran species were investigated by immunocytochemical methods for the presence of structures immunoreactive with a range of antisera raised to the mammalian regulatory peptides. The regulatory peptides involved were gastrin, cholecystokinin, motilin, secretin, gastric inhibitory polypeptide, pancreatic glucagon, enteroglucagon, glicentin, neurotensin, somatostatin, pancreatic polypeptide, vasoactive intestinal polypeptide, substance P, Met-enkephalin, bombesin, and β-endorphin. In the majority of the species investigated, immunoreactive epithelial endocrine cells were demonstrated with the antisera to somatostatin, gastrin, enteroglucagon, and neurotensin. Motilin-containing cells were observed in a single species, Ambystoma mexicanum. Of the peptides detected within the mammalian innervation, vasoactive intestinal polypeptide, substance P, Met-enkephalin, and β-endorphin immunoreactive nerve fibres were seen. The distribution of the immunoreactive nerves differed significantly with species. Bombesin immunoreactivity was not seen within the innervation, although a population of endocrine cells was detected within the corpus of several species. No immunoreactivity was observed with the antisera to secretin, gastric inhibitory polypeptide, or pancreatic polypeptide in the species investigated.
Effet de certains paramètres physico-chimiques sur les relations prédateurs–proies dans les populations de copépodes cyclopoïdes des mares temporaires d'eau douce
Authors: Vallières Louise , Aubin Antoine
Published: August 2008

Copepod populations of three temporary freshwater pools (Alnus unit, Carex unit, and Molinia unit) were studied using a standard approach (species versus abiotic factors) and a holistic one (body size and feeding ecology). Multiple regression analyses of data indicate that the physical and chemical features of water (temperature, pH, dissolved oxygen, mineral content, and depth) explain 62 to 98% of the variability of carnivorous copepods, while the abundance of their prey accounts for much less. No size class of prey seems to be preferred. The abundance of decaying organic matter, typical of such pools, would result in an overabundance of prey. Predators would then be under the control of nonalimentary factors.
Chromosomes and sex ratio of the collared lemming, Dicrostonyx richardsoni
Authors: Malcolm Jay R. , Brooks Ronald J. , Bogart James P.
Published: August 2008

The chromosomes of 18 laboratory-born Dicrostonyx richardsoni (= D. groenlandicus richardsoni) were examined. Eight females had 2n = 44 and two large metacentric chromosomes, three females and two males had 2n = 43 and three large metacentrics, and two females and three males had 2n = 42 and four large metacentrics. The observed chromosomal polymorphism was explained as a Robertsonian transformation in which metacentrics underwent centric fission to form two telocentrics, or two telocentrics fused to form a metacentric. No chromosomal differences were observed between males and females that had the same number of large metacentrics. The laboratory sex ratio at weaning was 0.38:1 (363 males, 596 females). Observed and expected distributions of proportions of male offspring among dams were significantly different if dams were assumed to produce males with binomial probability 0.5, or with probability 0.38. There was qualitative support for three female types, each producing males with probability 0.50, 0.25, or 0.33, as has been hypothesized for Dicrostonyx torquatus from Asia.
A cytological study of the Prosimulium onychodactylum complex (Diptera, Simuliidae)
Authors: Henderson Christine A. P.
Published: August 2008

This paper extends the known geographical and temporal distributions of forms of the morphospecies Prosimulium onychodactylum and consequently supplements the study of Newman (L. J. Newman. 1983. Can. J. Zool. 61: 2816–2835). Larvae were collected from 65 sites in northwestern North America, and six forms were observed. Forms 2a, 2b, and 4a/4b were previously characterized by Newman and forms 8, 9, and 10 are described here for the first time. Form 10 may be conspecific with Newman's form 6. Form 9 from the Yukon, with a unique Y chromosome inversion, may be a geographic variant of Newman's form 2. Form 8, characterized by a large chromocenter, is specifically distinct from all other forms. A cytophylogeny is given which indicates the chromosomal relationships among the forms presently recognized.
The effect of spawning time and incubation temperature on meristic variation in chum salmon (Oncorhynchus keta)
Authors: Beacham T. D. , Murray C. B.
Published: August 2008

Variability in the number of dorsal, anal, caudal, pectoral, and pelvic fin rays, vertebrae, and gill rakers of early and late spawning stocks of Chehalis River chum salmon (Oncorhynchus keta) incubated under controlled water temperatures of 4, 8, and 12 °C was examined. The early spawning stock had fewer dorsal fin rays, more anal fin rays, fewer pectoral and pelvic fin rays, and fewer gill rakers than did the late spawning stock. Chum salmon originally incubated at 4 °C had the lowest number of dorsal fin rays, but the highest number of vertebrae and gill rakers. Chum salmon originally incubated at 8 °C had the highest number of anal fin rays, and those incubated at 12 °C had the highest number of pectoral fin rays. Meristic phenotypes had both a genetic and an environmental component.
Responses by benthic macroinvertebrates to prolonged flooding of marsh habitat
Authors: Murkin Henry R. , Kadlec John A.
Published: August 2008

This study examined the seasonal differences in benthic invertebrate densities and biomass within the dominant vegetation types in a series of 5-ha experimental marshes in south central Manitoba. Following periods of normal water depths, the marshes were flooded to 1 m above the existing cattail beds for up to 2 years to determine the benthic invertebrate response to prolonged above-normal flooding of the marsh habitat. Benthic invertebrate densities and biomass were low during periods of normal water depths when compared with levels later during flooding. The benthic response to flooding was primarily within the herbivore–detritivore group, especially nonpredaceous chironomids. All cover types other than former open-water sites showed increases in benthos densities, biomass, and numbers of taxa following flooding. The increases following flooding appear to be related to the death of the belowground components of the emergent vegetation, the availability of coarse organic litter early in flooding, and the development of fine particulate organic matter during flooding.
Resistance to desiccation and starvation of two species of Brachinus (Coleoptera: Carabidae) from southeastern Arizona
Authors: Juliano Steven A.
Published: August 2008

Resistance to desiccation and starvation of two species of Brachinus were compared in laboratory studies, and the components of water and energy balance were determined. Brachinus mexicanus, which dominates at temporary ponds far from permanent water, survived desiccation or starvation longer than did B. lateralis, which dominates at permanent ponds. The difference in desiccation resistance was a result of greater tolerance of low body water and greater amount of expendable water in B. mexicanus. Neither rates of water loss nor spiracular control of water loss differed significantly between these two species. Brachinus mexicanus lost mass less rapidly when starved and had a lower resting metabolic rate than did B. lateralis, indicating that greater resistance to starvation was due to lower rate of energy consumption. Both species had similar amounts of stored energy reserves, and there was no evidence of change in metabolic rates due to starvation. Although these differences may be part of the explanation of the scarcity of B. lateralis at some temporary ponds, they do not explain the scarcity of B. mexicanus at permanent ponds.
Transferrin variation in caribou (Rangifer tarandus L.) on the Canadian Arctic islands
Authors: Røed K. H. , Staaland H. , Broughton E. , Thomas D. C.
Published: August 2008

Polyacrylamide gel electrophoresis was used to analyse transferrin variation in caribou from the Canadian Arctic islands. Sixteen alleles were detected in Peary caribou (Rangifer tarandus pearyi). The most common allele was TfG2, which increased in frequency from 0.167 at the Boothia Peninsula to 0.236 in the Peel population and 0.340 in the Parry population. The presence of this allele, which is the most common allele in Svalbard reindeer (R. t. platyrhynchus) and not detected in Norwegian reindeer (R. t. tarandus), suggests a common origin for the Peary caribou and the Svalbard reindeer. The large genetic distance in the transferrin locus between continental and island populations suggests the isolation of a High Arctic population in a northern refugium during the Wisconsin glaciation.
Life-history patterns of Haustorius canadensis (Crustacea: Amphipoda) in northern New England
Authors: Donn Jr. Theodore E. , Croker Robert A.
Published: August 2008

The population of Haustorius canadensis at Long Sands Beach in southern Maine was sampled monthly over a period of 45 months. The population showed seasonal movements upshore during spring and downshore during the autumn and winter. In southern Maine, H. canadensis has a mixed annual–biennial life history, with approximately one-half of the population reproducing after 1 year and the remainder reproducing during the second year. This pattern contrasts with the annual life history observed on the southern shore of Cape Cod. This shift in life history is discussed in terms of a gradient of habitat temperatures. The minimum size of a reproductive female was approximately 6 mm. Males were smaller than females. The sex ratio remains close to 1:1 throughout the year.
Recovery of white adipose tissue after lipectomy in female ground squirrels
Authors: Forger Nancy G. , Dark John , Zucker Irving
Published: August 2008

Female golden-mantled ground squirrels were subjected to surgical removal of adipose tissue (lipectomy) at 4 months of age. Compensation for the 9.6% reduction in body mass effected by lipectomy was observed within 2 weeks and body mass did not differ between lipectomized and sham-lipectomized groups from that time to the conclusion of the experiment. At the time of the second peak in body mass, approximately 11 months postoperatively, lipectomized and sham-lipectomized groups did not differ with respect to total carcass lipid content, water content, or fat-free dry mass. Restoration of body mass after lipectomy did not involve measurable increases in food consumption. There was complete restoration of the retroperitoneal fat depot, but little if any recovery in the parametrial fat depot which was reduced in mass by 75% relative to that of the sham-lipectomized squirrels. Precise regulation of the adipose tissue mass is an important component of the annual cycle in energy balance of female squirrels.