bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraspecific variation in reproductive effort by female Parapediasia teterrella (Lepidoptera: Pyralidae) and its relation to body size
Authors: Marshall Larry D.
Published: February 2008

Daily egg production of the moth Parapediasia teterrella declined over the life-span of the female but egg size remained constant. The absence of water resulted in lower fecundity and early mortality. Egg size and lifetime fecundity showed considerable inter-individual variation and large females produced more and larger eggs than their smaller counterparts. Large females expended greater reproductive effort than small females. Hatching success was negatively related to egg size. In spite of this, large females laying large eggs had higher fitness than small females. I postulate that multiple reproductive strategies within a species, resulting from differences in reproductive effort expended, may explain why expected trade-offs in reproductive parameters (e.g., egg size versus egg number) were not found in this species. Furthermore, I argue that the prevalent interpretation of life-history evolution (that body size is the important determining parameter of life-history parameters) may reflect correlation of body size with reproductive effort, and reproductive effort may be more important in determining the nature of trade-offs between reproductive parameters.
Aposematism or startle? Predators learn their responses to the defenses of prey
Authors: Bates David L. , Fenton M. Brock
Published: February 2008

We used the responses of four trained captive big brown bats (Eptisicus fuscus) to the clicks of arctiid moths to test the hypothesis that predators learn their responses to preys' defensive displays. Bats were trained to fly to a platform where they sometimes received a mealworm reward. On about 5% of the occasions on which bats came within 0.5 m of the platform, they were randomly presented with one of three acoustic stimuli, including recorded clicks of an arctiid moth, synthetic clicks (white noise temporally matched to arctiid clicks), or tape noise. It took less than three trials for the bats to habituate to the arctiid clicks and longer for them to cease responding to the other stimuli. In less than eight pairings of arctiid clicks and a noxious food reward, two of the bats learned to associate moth clicks with a bad taste. Our data support the hypothesis by showing that although unexpected clicks startle inexperienced bats, they may also warn experienced bats of bad-tasting prey.
Pathogenicity of Allantonematidae (Nematoda) infecting bark beetles (Coleoptera: Scolytidae) in Manitoba
Authors: Tomalak Marek , Welch Harold E. , Galloway Terry
Published: February 2008

Histological examination of pathogical changes caused by allantonematid nematodes infecting bark beetles was conducted using beetles collected from Nopiming Provincial Park and Belair, Whiteshell, and Agassiz provincial forests in Manitoba. Nematodes were classified into three groups according to the pattern and nature of damage caused to their hosts. Sulphuretylenchus (three species) induced the earliest and most dramatic changes in their hosts, affecting fat body integrity and ovary and sperm development, and causing massive damage to muscles throughout the body. A Parasitylenchus species induced less severe damage, affecting ovarian development and causing tissue damage only after numerous juvenile nematodes had been released by parasitic females. Neoparasitylenchus, Allantonema, and Contortylenchus caused gradual depletion of fat body reserves, and only minor tissue damage was caused by juvenile nematodes. The degree of pathological change was related to the timing of infection and release of juveniles by parasitic females and to the relative abundance of juveniles present in the haemocoel. Bark beetle species infected by Sulphuretylenchus constructed aberrant galleries, coincident with tissue degradation caused by juvenile nematodes.
Histological effects of vitamin A on limb regeneration in the larval axolotl, Ambystoma mexicanum
Authors: Scadding Steven R.
Published: February 2008

Vitamin A causes profound changes in the development of pattern during amphibian limb regeneration. Vitamin A effects include the induction of duplications of skeletal structures in the anteroposterior, proximodistal, and dorsoventral axes. The purpose of this investigation was to study the underlying histological changes that are induced in the regenerating limb of the larval axolotl, Ambystoma mexicanum, by treatment with vitamin A. Axolotl larvae (7–10 cm in length) had forelimbs amputated through the radius and ulna and were then immersed in 75 IU/mL retinol palmitate for 14 days. Limbs were removed and fixed at intervals over the period of regeneration, both during and beyond the period of retinoid treatment. They were then examined in the light microscope, scanning electron microscope, or transmission electron microscope. Compared with the controls, the retinol palmitate treated regenerating limbs exhibited the development of an eccentric epidermal cap which was always displaced towards the posterior edge of the limb. Beneath this epidermal cap, the density of the cells of the blastema was greater than that of the cells towards the anterior edge of the developing blastema where the cells were much less densely arranged. Epidermal changes induced by retinol palmitate included the development of a very uneven and creviced surface, with a great deal of variation in cell size, and the development of ciliated cells in the surface layer of the epidermis. The significance of these observations for pattern modification by vitamin A are discussed.
Thoracic anatomy of the Baikal seal, compared with some other phocid seals
Authors: Koster Margie D. , Ronald Keith , Bree Peter van
Published: February 2008

While undertaking the descriptive dissection of a Baikal seal (Phoca sibirica), the anatomy of the neck, thorax, and pectoral limbs were compared with that of a ringed seal, two harp seals, and two grey seals. Comparison of the myology showed the Baikal and the ringed seal to be the most similar, whereas the harp seals had more muscular subdivisions than the previous two species. The nonlobate lungs of the harp seal indicate a more advanced development. The grey seals were generally more robust with more pronounced areas of muscle attachment. Skeletal characteristics of the pectoral limb indicate that this species is the most primitive of the four.
Seasonal serum glucose, progesterone, and Cortisol levels of black bears (Ursus americanus)
Authors: Harlow Henry J. , Beck Thomas D. I. , Walters Lisa M. , Greenhouse Shelley S.
Published: February 2008

Sixty-two black bears were captured at different seasons during the years 1983–1987. Bears were anesthetized in their dens during the winter and parts of the fall and spring, while bears captured during the summer were snared prior to anesthesia. Radioimmunoassays for both Cortisol and progesterone were validated on black bear serum. An improved, rapid progesterone radioimmunoassay for black bear serum is reported. Serum glucose demonstrated a tendency for reduction during spring. Serum progesterone levels did not demonstrate seasonal differences and were significantly higher in females only during the summer ovulatory/postestrus period. Serum Cortisol was significantly elevated during the winter denning period as compared with the summer period. We conclude that differences in serum progesterone, Cortisol, and glucose may not be indicators of stress exposure, but of seasonal reproductive states and metabolic utilization of fat reserves.
Enzyme activity levels underestimate lactate production rates in cod (Gadus morhua) gas gland
Authors: Ewart H. Stephen , Driedzic William R.
Published: February 2008

Maximal in vitro activities of hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, β-hydroxyacyl-CoA dehydrogenase, citrate synthase, malate dehydrogenase, and cytochrome oxidase were assessed in cod (Gadus morhua) gas gland. The metabolic profile predicts a substantial anaerobic relative to aerobic metabolism. The effect of catecholamines, acetylcholine, and low pH on in vitro rates of lactate production by gas gland was assessed. Adrenaline and acetylcholine both increased the rate of lactate production even under aerobic incubation conditions. However, the rates of lactate production were well below the capacity suggested by the enzyme levels. It is suggested that the tissue has an abundance of enzymes that operate at submaximal rates.
The influence of sexual dimorphism on kleptoparasitism of Blue-footed Boobies by Brown Boobies
Authors: Tershy Bernie R. , Breese Dawn
Published: February 2008

In the Canal de Ballenas, Gulf of California, Mexico, we observed Brown Boobies (Sula leucogaster) steal food from Blue-footed Boobies (Sula nebouxii), a previously undescribed kleptoparasitic interaction. Brown Boobies were the primary kleptoparasite of Blue-footed Boobies. Of the 28 attacks recorded we determined the sex of the Brown Boobie 16 times, and in all cases the Brown Boobies were females, the larger of the two sexes. Kleptoparasitism may be facilitated by the juxtaposition of these two species, with slightly different foraging strategies, in mixed-species feeding flocks.
Aerial behaviour in sperm whales
Authors: Waters Susan , Whitehead Hal
Published: February 2008

This paper examines the nature and context of breaching (leaping from the water) and lobtailing (thrashing of flukes onto the water surface) in sperm whales (Physeter macrocephalus) using data principally collected off the Galápagos Islands. Animals generally breached on their sides at an angle of 30–50° to the water surface and with about 50–100% of their body showing at peak emergence. Breaches and lobtails were often found to occur in long sessions or "bouts" lasting up to several hours and at times containing over 250 individual activities. The rates of observing these activities did not vary seasonally, but breaching was seen more often in 1985 than in 1987, an El Niño year when the whales appeared to have reduced feeding success. Both breaching and lobtailing rates were highest in the late afternoon, although both activities occurred at all times of day and night. Bouts of breaches and lobtails were longer when several groups of sperm whales were together, and during long bouts, groups or small clusters of whales frequently merged or split up. Except for two breaches, all aerial activity was observed from groups of female and immature whales rather than from mature or maturing males on breeding or feeding grounds.
Tree lizard distribution and mating system: the influence of habitat and food resources
Authors: M'Closkey Robert T. , Deslippe Richard J. , Szpak Christopher P. , Baia Keith A.
Published: February 2008

We examined the distribution of an insectivorous iguanid lizard (Iguanidae: Urosaurus ornatus, tree lizard) in the Sonoran Desert of Arizona in 1984, 1986, and 1987. The purpose of the investigation was to examine the ecological correlates of lizard distribution and mating system. Data from 420 marked lizards which were captured 1552 times provided information on habitat-level differences in lizard numbers and characteristics of home ranges in which oviposition occurred. In addition, we evaluated the role of arthropod food resources in the distribution of female home range and in the mating status of males. In dry washes tree lizards occupied mesquite (Prosopis juliflora) trees, whereas in flatland habitat they lived in mesquite trees and other sites (dead mesquite and saguaro cactus, Carnegeia gigantea). Lizards were more abundant in dry washes than flatland habitat. The lizard mating system was variable and a greater proportion of males were polygynous in wash (33–67%) compared with flatland (7–33%) habitat. In the flatland, home ranges in which females oviposited could be distinguished from vacant sites by soil hardness, shrub cover, and the presence of wood rat (Neotoma albigula) nests. Arthropod abundance did not differ between female home ranges and nearest vacant site nor between habitats and among male territories. Therefore, food resource distribution does not appear to be a determinant of either female distribution or territory quality in male tree lizards.
Plasma concentrations of glucocorticoids in white-tailed deer: the effect of acute ACTH and dexamethasone administration
Authors: Smith J. H. , Bubenik G. A.
Published: February 2008

To study the response of the adrenal gland of white-tailed deer to exogenous ACTH, eight penned animals (five mature intact males, one mature castrate male, one adult castrate female, and one immature female) were sedated with xylazine and ketamine and then challenged with various doses of ACTH with and without dexamethasone (DX) pretreatment. Plasma concentrations of cortisol and cortiscosterone were determined by radioimmunoassay in serial samples taken from a jugular cannula. Rapid, dose-dependent increases lasting over 5 h were observed after intramuscular injection of 10, 20, or 40 IU of porcine ACTH. The ratio of cortisol to corticosterone varied from 2:1 to 40:1. Maximum cortisol concentrations averaged 14.9, 20.3, and 21.3 μg/dL, respectively. Intravenous infusion of 5 mg of DX induced a rapid decline of cortisol levels. Administration of 20 or 40 IU of ACTH 140 min after DX caused increases of cortisol which were not different from those when ACTH was given alone. It was concluded that (i) xylazine and ketamine immobilization is suitable for study of the adrenal activity in deer, (ii) 20 IU of ACTH elicits maximal response of cortisol and corticosterone, (iii) DX pretreatment can result in minimal cortisol concentrations but its use is not essential for studies of adrenal response to ACTH, and (iv) the adrenal response to ACTH of females and castrate males is similar to that of intact males.
Classification of Tertiary fossil Donaciinae of North America and their implications about evolution of Donaciinae (Coleoptera: Chrysomelidae)
Authors: Askevold Ingolf S.
Published: February 2008

Specimens of Donacia primaeva Wickham from the Oligocene Florissant shales of Colorado are indistinguishable from male specimens of the extant species Plateumaris nitida (Germar), and are assigned to the P. nitida group. A fossil from the Late Paleocene Paskapoo Formation of Alberta (Donacia wightoni n.sp.) is the oldest fossil of Donaciinae, assigned to Donacia (Donacia), an ecologically and structurally highly derived subgenus. Both species are assigned to small groups of extant species which are not the most primitive Donaciinae. They are similar to extant taxa, which suggests they have maintained considerable structural stasis over a long period of time.
Genic homogeneity among temporal populations of the eastern chipmunk (Tamias striatus)
Authors: White Matthew M. , Svendsen Gerald E.
Published: February 2008

A population of eastern chipmunks (Tamias striatus) was surveyed for allozyme variation over two distinct reproductive seasons each year during 1987 and 1988. Individuals were placed into resident, recruit, and disappearing individual categories for the allozyme analysis. The resident population declined by 43% during the period of the study. Individuals in the recruit and emigrant categories accounted for about 50% of the population each season and the number in each of these categories varied widely from season to season. No inbreeding, based on genotype frequencies, was observed within the resident population. No significant genic heterogeneity was observed among temporally separated populations of chipmunks in the resident, recruit, or disappearing individual categories. The high levels of additions and losses from the population and the complex age-structure of chipmunk populations were likely the major contributors to the lack of inbreeding and seasonal differentiation. These results are contrasted with the more widely studied microtine systems.
The behaviour and the relationship between food intake and growth of juvenile Arctic charr, Salvelinus alpinus L., subjected to sustained exercise
Authors: Christiansen Jørgen Schou , Jobling Malcolm
Published: February 2008

The effects of long-term moderate exercise on the behaviour and the food intake – growth relationship of individually marked Arctic charr, Salvelinus alpinus L., were examined. Direct monitoring of food intake of individual fish was carried out using an X-radiographic method. Growth (weight gain) was significantly improved with increasing swimming speed, and a maximum specific growth rate was obtained at a swimming speed of approximately 1.75 body lengths/s. Growth appeared to be suppressed by high levels of aggressive interactions, and an increase in swimming speed caused a marked increase in schooling behaviour, with a concomitant reduction in agonistic activity. The exercising fish did not consume more food than controls, and moderately exercised Arctic charr showed improved growth – food intake ratios at all levels of food intake compared with fish held in standing water. Furthermore, the proportions of nonfeeding fish were significantly reduced at increasing water velocities. Thus, the relationship between food intake and growth may be strongly influenced by agonistic activity, which appears to be most prevalent in fish subjected to low water velocities.
Quantitative analysis of prey-capture kinematics in Anolis equestris (Reptilia: Iguanidae)
Authors: Bels Vincent L.
Published: February 2008

High-speed cinematography was employed to study the mechanics of prey capture in Anolis equestris. Capture of live prey (adult locusts) consists of a cyclic movement of the upper and lower jaws combined with tongue protraction. Kinematic profiles are presented for the jaws, tongue, and forelimbs. The tongue is projected during the "slow open" stage and most of the "fast open" stage. The tongue protrudes beyond the mandibular symphysis during the slow open stage, and rotates simultaneously around a transverse anteromedian axis. The prey is thus contacted by the dorsal sticky surface of the tongue, and then pulled backward into the oral cavity by a combination of a forward movement of the jaws and retraction of the tongue. Gape angle, defined as the angle between the upper and lower jaws, continues to increase during the initial stages of tongue retraction. During the capture process, the anterior part of the body lunges forward, followed by a return to its original position; this displacement is mediated by the forelimbs, which usually remain well anchored to the floor. The cyclic food-capture movements of the jaws and tongue–hyoid system in A. equestris (Iguanidae) and Chameleo dilepis (Chamaeleontidae) are compared. I argue that one of the primary selection forces in the evolution of the different mechanisms of prey prehension in these two lizard groups was enhancement of the locomotor system and, consequently, foraging ability.
Distribution des populations d'Artemia et de leur parasite Flamingolepis liguloides (Cestode, Cyclophyllidea), dans les salins du littoral méditerranéen français
Authors: Thiéry Alain , Robert Florence , Gabrion Claude
Published: February 2008

The occurrence of the cysticercoïd stage of the bird tapeworm Flamingolepis liguloïdes (Cestoda, Cyclophyllidea) was studied across the salt marshes of the French Mediterranean coast. It was observed in 11 populations of the intermediate host Artemia (Crustacea, Anostraca) and investigated. A relationship between the prevalence of the parasite in Artemia and the population density of flamingoes on the sites studied is shown by the results. Parasitism in the infected host populations increases with the size of Artemia. Cysticercoïds are found in the thorax of juvenile Artemia, whereas they are packed in the abdomen in the adults. During growth of Artemia, the localisation of parasites is related to allometric changes in the thorax/abdomen proportion. In infected populations, up to 22.8% of Artemia are red coloured and present an altered behaviour. These physiological and ethological changes are discussed in terms of adaptive strategy by the parasite.
Habitat use by male mink in relation to wetland characteristics and avian prey abundances
Authors: Arnold Todd W. , Fritzell Erik K.
Published: February 2008

We documented use of wetland habitats by five radio-marked male mink (Mustela vison) in the aspen parklands of southwestern Manitoba during May–July of 1984 and 1985. Mink activity was most frequent on large, well-flooded, semipermanent and permanent wetlands with irregular shorelines and large areas of open water. These variables were also positively correlated with abundances of waterfowl and other birds. Habitat variables explained 26% of the variation in wetland use by male mink. Grebes, coots, and diving ducks had high habitat overlap with mink, whereas dabbling ducks and blackbirds overlapped little with mink. Bird abundances explained nearly as much variation in habitat use by mink as did physical habitat variables (R2 = 0.24), but some of this association may have been due to selection for (or avoidance of) similar habitats. Combined analysis with habitat and avifaunal variables explained 31% of the variation in wetland use by male mink. Patterns of habitat use by mink and avian prey may help explain previously documented trends of prey selection among prairie mink.
Surface foraging behaviour of the North Atlantic right whale, Eubalaena glacialis, and associated zooplankton characteristics
Authors: Mayo Charles A. , Marx Marilyn K.
Published: February 2008

Right whales in Cape Cod Bay, Massachusetts, were studied to determine the relationship between their surface feeding behaviour and the density and composition of their planktonic prey. The swimming path characteristics of whales feeding, socializing, and travelling were compared. Zooplankton samples collected in the feeding path were contrasted with those from areas where whales were not present. Surface prey patches where right whales fed were dominated by Calanus finmarchicus (21 samples), Pseudocalanus minutus (n = 13), Centropages sp. (n = 3), and larval barnacles (n = 2). The zooplankton density in the feeding path of the whales tested significantly higher (Mann–Whitney U-test, P < 0.001) than at stations where whales were not present (mean total densities were 6.54 × 103 (SE = 1.03 × 103) and 0.87 × 103 (SE = 0.19 × 103) organisms/m3, respectively). Feeding was rarely observed in locations where the total zooplankton density was less than 1000 organisms/m3. The rate of change of direction in the feeding path (mean 19.3°/10 m of path) was significantly higher (P < 0.001) than for paths of whales travelling (mean 5.3°/10 m of path), reflecting area-restricted foraging behaviour.
Caractéristiques biodémographiques d'un acarien oribate (Carabodes willmanni) des pelouses xérophiles
Authors: Bellido A.
Published: February 2008

An analysis of biodemographic characteristics was undertaken under experimental conditions in Carabodes willmanni, the first study of its kind in the superfamily Carabodoidea. The species dominates the microarthropod fauna of dry Cladonia cover. Immature stages have a very soft integument and live within the decomposing lichen layer. The population is characterized by the following: (i) low fecundity, strongly density dependent; (ii) relatively long postembryonic development for such a small species, lasting 117 days at 20 °C; (iii) extended premoulting stage (pupation), lasting 28% of postembryonic development; (iv) high but very variable longevity, with values varying from 200 to 600 days between egg laying and death of the adult; (v) strong influence of temperature on fecundity, adult survival, and duration of embryonic and postembryonic developments: development is inhibited at 10 °C. Based on previously acquired information on the phenology of the population, a model for the life cycle under natural conditions is proposed. Periods favorable to development being greatly shortened by environmental factors, the duration of the cycle is lengthened and probably takes as much as 1 year under the harshest conditions. The success of C. willmanni in such an environment can be explained by the capacity of the immature stages to take advantage of the lichen substrate both as a source of food and as a means of protection against desiccation.[Journal translation]
The genus Odontocepheus (Acari: Oribatida: Carabodidae) in North America, with description of a new species
Authors: Reeves R. Marcel
Published: February 2008

Adults of Odontocepheus rumbleseatus n.sp. are described, the second Odontocepheus species known from North America. An unusual, deep posterior depression on the notogaster easily separates this species from all others in the genus Odontocepheus. Specimens were collected from hardwood leaf litter and rotten wood. The known distribution is Illinois and West Virginia south to northern Florida. Additional characters for separating the North American species O. oblongus (Banks) from O. elongatus (Michael) in Europe are presented, and the presence of O. elongatus in North America is documented.
Mating behaviour and spermatophore morphology: a comparative test of the female-choice hypothesis
Authors: Proctor Heather C. , Baker Robert L. , Gwynne Darryl T.
Published: February 2008

Complex, species-specific morphology of genitalia or "paragenitalia" such as spermatophores is traditionally considered an adaptation to prevent heterospecific matings. Eberhard argued against this lock-and-key hypothesis and suggested that elaborate male genitalia evolve through female preference for increased tactile stimulation. He found support for this argument in a cross-taxon comparison of spermatophore complexity among species with different degrees of contact between the sexes during spermatophore transfer. After expanding Eberhard's list of species, we tested the female-choice hypothesis with appropriate controls for phylogeny and using naive human subjects to rank spermatophore complexity. Our results uphold Eberhard's conclusion that the lock-and-key hypothesis does not explain the distribution of spermatophore complexity among taxa; however, they do not clearly support female choice as an alternative explanation. Other factors that may influence spermatophore complexity include environmental stress and whether spermatophores are deposited on a substrate. Because we seldom know what parts of a spermatophore are touched by females, or whether there are spermatophore-associated pheromones, human visual assessment may not always allow accurate judgement of realized spermatophore complexity.
The diet of insectivorous ducklings and the acidification of small Ontario lakes
Authors: Bendell Barry E. , McNicol Donald K.
Published: February 2008

We examined the diet of insectivorous ducklings of four species of waterfowl, Common Goldeneye (Bucephala clangula), Ring-necked Duck (Aythya collaris), Hooded Merganser (Lophodytes cucullatus), and American Black Duck (Anas rubripes), collected from small lakes covering a range of acidity in northeastern Ontario. The numbers of Odonata larvae, aquatic Hemiptera, aquatic Coleoptera, and Trichoptera larvae eaten by the ducklings were estimated from combined esophageal and gizzard contents and analysed with respect to differences in lake acidity and fish presence. Ducklings of all species, especially Common Goldeneye and Hooded Merganser, ate significantly more nektonic prey, especially Notonectidae (Hemiptera) and Dytiscidae (Coleoptera), from lakes without fish than from lakes with fish. Ducklings of species other than American Black Duck ate more Anisoptera larvae on acidic lakes. American Black Duck ducklings ate more teneral Odonata on acidic lakes. There was a tendency for more Trichoptera larvae to be eaten on non-acidic lakes than on acidic lakes. All four species adjusted, to some extent, for the absence of acid-sensitive prey in acidified lakes by feeding on prey that are most abundant under acidic, Ashless conditions. Differences in diet among species were related to differences in diving and foraging behaviour, and to hatch date.
Incubation temperature affects sexual differentiation, incubation time, and posthatching survival in desert tortoises (Gopherus agassizi)
Authors: Lewis-Winokur Vanessa , Winokur Robert M.
Published: February 2008

Eggs of captive desert tortoises. Gopherus agassizi, incubated at six temperatures (25, 27, 28, 29, 29.4, and 31 °C) produced 107 specimens. Eggs incubated at 31 °C resulted in a male to female sex ratio of 5:7; all other incubation temperatures resulted in males only. Histological examination of gonads revealed that the testes of newly hatched to 3-month-old individuals showed incomplete and poorly developed seminiferous tubules. Female gonads showed a thickened cortex. Incubation times were longer at lower temperatures. Both hatching success and hatchling survivorship were lower at lower incubation temperatures. We confirm that temperature-dependent sex determination occurs in desert tortoises and that the pivotal temperature is between 31 and 32 °C.
Sex differences in behavior of beavers living in near-boreal lake habitat
Authors: Buech Richard R.
Published: February 2008

Comparative studies of how female and male North American beavers (Castor canadensis) allocate time provide a basis for understanding their life history. I studied the behavior of beavers living in lake habitats of a near-boreal region to determine how animals of each sex allocated time during their active periods. Markov time-budget estimates revealed that over the open-water season, adult females and males spent 91 and 86%, respectively, of time during active periods feeding, traveling, and being in the lodge. Adult females spent most of their time feeding in late spring and summer. In late summer through fall, they spent more time provisioning, working on lodges, and constructing winter food caches. In contrast, adult males spent less time feeding and more time traveling, being in the lodge, and working on the lodge in late spring and early summer. As the season progressed, adult males traveled less and spent more time feeding and working on the lodge. Overall, the results suggest that there is a division of labor in this monogamous species. Adult females seemed to function primarily as providers of energy to kits. In contrast, adult males seemed to function primarily in protection and provisioning of kits, territory maintenance, and construction and maintenance of structures.
Evolutionary history of threespine sticklebacks (Gasterosteus spp.) in British Columbia: insights from a physiological clock
Authors: Kassen Rees , Schluter Dolph , McPhail John Donald
Published: February 2008

Geologic and allozyme evidence suggests that threespine sticklebacks (Gasterosteus aculeatus complex) in low-lying southwestern British Columbia lakes were founded during two incursions of marine sticklebacks after the retreat of the Pleistocene glaciers (the double-invasion hypothesis). We used the salinity tolerance of embryos, measured as hatchability in salt water, to establish the relative order of freshwater invasion by marine sticklebacks and to test the double-invasion hypothesis. Limnetics and an anadromous population hatched nearly equivalent numbers of young in salt water as in fresh water, whereas benthics and one solitary freshwater population had low hatchability in salt water. We also found that eggs from freshwater populations were larger than those from marine populations and limnetics had smaller eggs than benthics and the solitary population. These results support the double-invasion hypothesis and suggest a trend of increasing egg size with increasing time spent in fresh water.
The relationship between specific growth rate and swimming performance in male fathead minnows (Pimephales promelas)
Authors: Kolok Alan S. , Oris James T.
Published: February 2008

The objective of this study was to test the hypothesis that the specific growth rate of male fathead minnows (Pimephales promelas) was positively correlated with swimming performance. Subadult fish were allowed to grow into adults over a period of 31 – 55 days, after which the critical swimming speed of each fish was determined. Variation in critical swimming speed was substantial (greater than 50%), and a significant positive correlation was found between number of growing days and critical swimming speed, whereas a significant negative correlation was found between specific growth rate and critical swimming speed. A multiple regression using specific growth rate and number of growing days explained over 47% of the variation in swimming performance. Fathead minnows that grow fast are poor swimmers, suggesting a trade-off between swimming performance and specific growth rate in this species.
Comment: Why do beavers exhibit free-running activity rhythms in winter?
Authors: Marchand Peter J.
Published: February 2008

Measurements of irradiance in northern ponds under ice and snow cover raise questions as to why beavers often show free-running activity rhythms in winter.
Metabolic rate in female European roe deer (Capreolus capreolus): incidence of reproduction
Authors: Mauget Christiane , Mauget Robert , Sempéré Antoine
Published: February 2008

Indirect calorimetry measurements were made continuously over a 2-year period in 10 adult female roe deer (Capreolus capreolus) maintained in outdoor enclosures on ad libitum feeding. Results from adult nonpregnant does revealed no endogenous seasonal rhythm in resting metabolic rate (RMR), in contrast to most cervid species. Throughout the 2 years of our study, RMR (overall mean 4695 ± 65 kJ∙d−1) fluctuated in parallel with variations in body mass. The mass-specific RMR ranged from 221.2 ± 4.8 to 230.7 ± 4.0 kJ∙kg−1∙d−1(466.0 ± 10.8 to 495.5 ± 9.7 kJ∙kg−0.75∙d−1). Results from pregnant females (five in the first year, four in the second) showed that their energy expenditure increased by 15% during the last 2 months of gestation, in step with the increase in body mass. A 27% increase in RMR was recorded in lactating females during the first month post partum. These results show that in a small-bodied cervid such as the roe deer, reproduction costs are no higher than in other wild herbivores.
Seasonal changes in diets of coastal and riverine mink: the role of spawning Pacific salmon
Authors: Ben-David M. , Hanley T. A. , Klein D. R. , Schell D. M.
Published: February 2008

Feeding niches of riverine and coastal mink (Mustela vison) in southeast Alaska differ in prey composition and abundance and diving medium during spring and summer. In autumn, however, the upstream migration of spawning Pacific salmon (Oncorhynchus sp.) creates a pulse of food for mink. We hypothesized that diets of coastal and riverine mink, and therefore their stable isotope ratios (δ13C, δ15N), would differ significantly during periods when salmon were absent, but that salmon carcasses would constitute a large portion of the diet of both groups during the salmon spawning season. Stable isotope analyses of clotted blood cells from 24 live-captured mink and muscle tissue from 25 mink carcasses were used to indicate the composition of diets of individual mink in 1992 and 1993. These isotope values were then compared with stable isotope ratios of prey, using a multiple-source mixing model. Our results indicate that riverine mink depended on salmon (carcasses and fry), with little seasonal or individual variation, whereas coastal mink relied on intertidal organisms in spring and summer, with measurable (<25%) consumption of salmon carcasses when they became available in autumn. Coastal and riverine mink in southeast Alaska differ strongly in their diets in spring and summer, with both groups relying on the abundant salmon carcasses during autumn.
Winter activity patterns of American martens (Martes americana): rejection of the hypothesis of thermal-cost minimization
Authors: Drew Gary S. , Bissonette John A.
Published: February 2008

Despite their temperate to subarctic geographic range, American martens (Martes americana) possess a thermally inefficient morphology. The lack of morphological adaptations for reducing thermal costs suggests that marten may use behavioral strategies to optimize thermal budgets. During the winters of 1989–1990 and 1990–1991, we radio-collared and monitored the diel activity of 7 martens. A log-linear model suggested that the presence or absence of light was the only factor associated with marten activity patterns (p < 0.001). A regression of the percentage of active fixes on ambient temperature failed to detect an association (b = −4.45, p = 0.084, n = 12). Contents of marten scats suggested that their activity was consistent with the prey-vulnerability hypothesis. While martens must balance multiple life requisites, their activity patterns suggest that they accept increased thermal costs in order to increase foraging efficiency. However, the nocturnal activity of martens during winter was also consistent with the hypothesis that they may be able to limit their own exposure to predation risk. The nocturnal habits of Newfoundland martens in the winter were consistent with the hypothesis of avoidance of predation risk.
Oxygen consumption and Na+,K+-ATPase activity of rectal gland and gill tissue in the spiny dogfish,Squalus acanthias
Authors: Morgan John D. , Iwama George K. , Wilson Jonathan M.
Published: February 2008

Oxygen consumption was measured in rectal gland and gill tissue of the spiny dogfish (Squalus acanthias) to estimate the energy cost of salt (NaCl) transport in these osmoregulatory organs. Ouabain (0.5 mM) was used to specifically inhibit Na+,K+-ATPase activity and thus the portion of tissue respiration required by the Na+/K+pump. The total mass-specific oxygen consumption of rectal gland tissue (14.2 ± 1.2 μmol O2/(g wet mass∙h)) was significantly higher than measured for the gills (9.6 ± 1.4 μmol O2/(g wet mass∙h)), and ouabain significantly reduced oxygen consumption in both tissues. Ouabain-sensitive oxygen consumption of the rectal gland accounted for 55% of total mass-specific oxygen consumption, compared with 22% for the gill. The higher ion transport capacity of the rectal gland was also evident in Na+,K+-ATPase specific activity measurements of fresh tissue samples, which were sixfold higher in the rectal gland than in the gill. Ouabain-sensitive oxygen consumption was also calculated on the basis of total organ mass to determine the portion of whole-animal oxygen uptake related to organismal NaCl transport. The cost of NaCl secretion was estimated to be 0.5% of standard metabolic rate for the rectal gland compared with 0.14% for the gills, suggesting that this process constitutes a relatively small portion of the total energy budget in the spiny dogfish.
INTRINSICALLY n-LINKED COMPLETE BIPARTITE GRAPHS
Authors: O'DONNOL DANIELLE
Published: February 2008

We prove that every embedding of K2n+1,2n+1 into ℝ3 contains a non-split link of n components. Further, given an embedding of K2n+1,2n+1 in ℝ3, every edge of K2n+1,2n+1 is contained in a non-split n-component link in K2n+1,2n+1.
THE KAUFFMAN POLYNOMIALS OF PRETZEL KNOTS
Authors: LU BIN , ZHONG JIANYUAN K.
Published: February 2008

Let ℚ(α, s) be the field of rational functions in α, s. We compute the Kauffman polynomials of pretzel knots [1,6] using the Kauffman skein theory and linear algebra tools. We give a formula for the Kauffman polynomial of a pretzel knot such that after inputting the sequence notation of the pretzel knot, the output is its Kauffman polynomial. Our calculation can be implemented in Mathematica, Maple, Mathcad, etc.
QUATERNIONIC INVARIANTS OF VIRTUAL KNOTS AND LINKS
Authors: BARTHOLOMEW ANDREW , FENN ROGER
Published: February 2008

In this paper, we define and give examples of a family of polynomial invariants of virtual knots and links. They arise by considering certain 2 × 2 matrices with entries in a possibly non-commutative ring, for example, the quaternions. These polynomials are sufficiently powerful to distinguish the Kishino knot from any classical knot, including the unknot.
DESIRABLE PROPERTIES OF AN IDEAL RISK MEASURE IN PORTFOLIO THEORY
Authors: RACHEV SVETLOZAR , ORTOBELLI SERGIO , STOYANOV STOYAN , FABOZZI FRANK J. , BIGLOVA ALMIRA
Published: February 2008

This paper examines the properties that a risk measure should satisfy in order to characterize an investor's preferences. In particular, we propose some intuitive and realistic examples that describe several desirable features of an ideal risk measure. This analysis is the first step in understanding how to classify an investor's risk. Risk is an asymmetric, relative, heteroskedastic, multidimensional concept that has to take into account asymptotic behavior of returns, inter-temporal dependence, risk-time aggregation, and the impact of several economic phenomena that could influence an investor's preferences. In order to consider the financial impact of the several aspects of risk, we propose and analyze the relationship between distributional modeling and risk measures. Similar to the notion of ideal probability metric to a given approximation problem, we are in the search for an ideal risk measure or ideal performance ratio for a portfolio selection problem. We then emphasize the parallels between risk measures and probability metrics, underlying the computational advantage and disadvantage of different approaches.
THE LEAST COST SUPER REPLICATING PORTFOLIO IN THE BOYLE–VORST MODEL WITH TRANSACTION COSTS
Authors: CHEN GUAN-YU , PALMER KEN , SHEU YUAN-CHUNG
Published: February 2008

Boyle and Vorst work in the framework of the binomial model and derive self-financing strategies perfectly replicating the final payoffs to long and short positions in call and put options, assuming proportional transactions costs on trades in the stock and no transactions costs on trades in the bond. Even when the market is arbitrage-free and a given contingent claim has a unique replicating portfolio, there may exist super replicating portfolios of lower cost. Bensaid et al. gave conditions under which the cost of the replicating portfolio does not exceed the cost of any super replicating portfolio. These results were generalized by Stettner, Rutkowski and Palmer to the case of asymmetric transaction costs.

In this paper, we first determine the number of replicating portfolios and then compute the least cost super replicating portfolio for any contingent claim in a one-period binomial model. By using the fundamental theorem of linear programming, we show that there are only finitely many possibilities for a least cost super replicating portfolio for any contingent claim in a two-period binomial model. As an application of our results, we give an example in which we compute the least cost super replicating portfolio for a butterfly spread in a two-period model.
The Identification of MicroRNAs in a Genomically Unstable Region of Human Chromosome 8q24
Authors: Huppi Konrad , Volfovsky Natalia , Runfola Timothy , Jones Tamara L. , Mackiewicz Mark , Martin Scott E. , Mushinski J. Frederic , Stephens Robert , Caplen Natasha J.
Published: February 2008

The PVT1 locus is identified as a cluster of T(2;8) and T(8;22) “variant” MYC-activating chromosomal translocation breakpoints extending 400 kb downstream of MYC in a subset (≈20%) of Burkitt's lymphoma (vBL). Recent reports that microRNAs (miRNA) may be associated with fragile sites and cancer-associated genomic regions prompted us to investigate whether the PVT1 region on chromosome 8q24 may contain miRNAs. Computational analysis of the genomic sequence covering the PVT1 locus and experimental verification identified seven miRNAs. One miRNA, hsa-miR-1204, resides within a previously described PVT1 exon (1b) that is often fused to the immunoglobulin light chain constant region in vBLs and is present in high copy number in MYC/PVT1–amplified tumors. Like its human counterpart, mouse mmu-miR-1204 represents the closest miRNA to Myc (∼50 kb) and is found only 1 to 2 kb downstream of a cluster of retroviral integration sites. Another miRNA, mmu-miR-1206, is close to a cluster of variant translocation breakpoints associated with mouse plasmacytoma and exon 1 of mouse Pvt1. Virtually all the miRNA precursor transcripts are expressed at higher levels in late-stage B cells (including plasmacytoma and vBL cell lines) compared with immature B cells, suggesting possible roles in lymphoid development and/or lymphoma. In addition, lentiviral vector-mediated overexpression of the miR-1204 precursor (human and mouse) in a mouse pre–B-cell line increased expression of Myc. High levels of expression of the hsa-miR-1204 precursor is also seen in several epithelial cancer cell lines with MYC/PVT1 coamplification, suggesting a potentially broad role for these miRNAs in tumorigenesis. (Mol Cancer Res 2008;6(2):212–21)
Krüppel-Like Factor 4 Is a Novel Mediator of Selenium in Growth Inhibition
Authors: Liu Shuang , Zhang Haitao , Zhu Liyu , Zhao Lijuan , Dong Yan
Published: February 2008

A previous prevention trial showed that selenium supplementation was effective in reducing (by 50%) the incidence of prostate cancer. Selenium has been reported to inhibit the growth of prostate cancer cells in vitro. Multiple mechanisms are likely to be operative in the underlying effect of selenium. Here, we report that Krüppel-like factor 4 (KLF4), a transcription factor of the KLF family, is an important target of selenium. We found that selenium up-regulates KLF4 expression and increases the DNA-binding activity of KLF4 in both the androgen-dependent LNCaP and the androgen-independent PC-3 human prostate cancer cells. The increase of KLF4 mRNA is accounted for primarily by enhanced transcription, although the contribution of a slight abatement in mRNA degradation cannot be ruled out. KLF4 knockdown using short interference RNA significantly weakens the effects of selenium on DNA synthesis inhibition, apoptosis induction, and the expression of three KLF4 target genes, cyclin D1, p21/WAF1, and p27/Kip1. In addition, the overexpression of KLF4 not only leads to an induction of apoptosis in the control cells, but also enhances the DNA synthesis–suppressive and–proapoptotic activities of selenium. Taken together, our results suggest that KLF4 plays a key role in mediating the growth-inhibitory effect of selenium in prostate cancer cells. (Mol Cancer Res 2008;6(2):306–13)