bluuebunny/crossref_metadata_2025 huggingface dataset:
Caractéristiques des peuplements forestiers recherchés par le cerf de Virginie en hiver à la limite nord de son aire de répartition
Authors: Dumont André , Ouellet Jean-Pierre , Crête Michel , Huot Jean
Published: April 2011

Nous avons étudié les préférences hivernales dhabitat chez le Cerf de Virginie (Odocoileus virginianus) dans l'est du Québec. Dans ces conditions limites d'environnement, la mortalité hivernale par inanition peut dépasser 40% lors dhivers rigoureux. Afin d'identifier les paramètres du milieu reliés à la répartition des cerfs, nous avons analysé la répartition des fèces et du broutement à partir d'inventaires réalisés aux printemps 1994 et 1995. Une analyse de régression multiple a retenules variables explicatives suivantes : le type de peuplement, le couvert en conifères (relation positive), la quantité de tiges arbustives feuillues disponibles (relation positive), le diamètre moyen des arbres d'espèces décidues (relation négative). Parallèlement, l'évolution de la fréquentation des peuplements par les cerfs durant lhiver a été suivie par des relevés des pistes dans la neige. Les cerfs ont utilisé tous les types de peuplement au début de l'hiver mais ont préféré les peuplements mélangés à dominance de conifères et évité les peuplements de feuillus lorsque les conditions d'enneigement sont devenues plus contraignantes. Nous suggérons un aménagement de la forêt visant à favoriser la venue de peuplements mixtes destructure inéquienne possédant un couvert en conifères compris entre 50 et 80%, ce qui permettrait aux cerfs de trouver, au même endroit, abri et nourriture.
Genetic evidence for a Hyalella species complex within the Great Lakes - St. Lawrence River drainage basin: implications for ecotoxicology and conservation biology
Authors: Hogg Ian D , Larose Céline , Lafontaine Yves de , Doe Kenneth G
Published: April 2011

We examined the population genetic structure (allozyme variation) of Hyalella azteca (Saussure) (Amphipoda:Crustacea) collected from six field locations and one laboratory culture within and near the Great Lakes  St. Lawrence Riverdrainage basin. We found considerable variability in allele frequency among locations. Wrights FSTvalue averaged over 10polymorphic allozyme loci was 0.56 (range 0.100.93), indicating very great levels of genetic differentiation amonglocations. Analyses of genetic distance (Neis, Rogers) suggested the presence of four genetically distinct groups. For thelaboratory population, differences were of sufficient magnitude to merit consideration as a separate (presently undescribed)species of Hyalella, showing fixed differences at 2 of 10 loci examined. The presence of genetically distinctspecies/populations within H.azteca potentially confounds the results of laboratory ecotoxicology tests, depending on whichindividuals are used in an analysis. Accordingly, we urge caution where results may be used to establish water-quality criteria.From a conservation perspective, the presence of an undescribed species within a relatively well known taxon such as H.aztecasuggests that current taxonomic inventories of benthic invertebrates may not only be incomplete, but perhaps grosslyunderestimated. We advocate a taxonomic reevaluation of H azteca and other widespread benthic taxa, with particular
A proposed three-host life history of Monascusfiliformis (Rudolphi, 1819) (Digenea: Fellodi-stomidae) in the southwest Atlantic Ocean
Authors: Martorelli SR , Cremonte F
Published: April 2011

This is the first record of cercariae of Monascus filiformis (Rudolphi, 1819) and of Chaetognatha as a secondintermediate host in the southwest Atlantic Ocean. The morphology of the sporocyst and cercaria from Nucula obliqua (Bivalvia:Nuculidae) and a full description of the metacercaria from hydromedusae are given. The life cycle of M. filiformis involves threehosts. The bivalve N. obliqua is the first intermediate host, Chaetognatha and medusae are the second intermediate hosts, and thejurel Trachurus lathami (Pisces: Carangidae) is the final host. The life cycle of M. filiformis occurs in shallow waters in theArgentine Sea and differs from Køies experimental scheme for the North Sea in the addition of planktonic invertebrates assecond intermediate hosts. The life cycle proposed here follows the general pattern given for the family Fellodistomidae.
Underwater nesting by the Australian freshwater turtle Chelodina rugosa: effect of prolonged immersion and eggshell thicknesson incubation period, egg survivorship, and hatchling size
Authors: Kennett Rod , Christian Keith , Bedford Gavin
Published: April 2011

The northern long-necked turtle, Chelodina rugosa, occupies seasonally ephemeral freshwater wetlands in thewetdry tropics of northern Australia. The species has a highly unusual nesting strategy in that nesting takes place under waterwhen wetland habitats are flooded. Embryonic development proceeds when floodwaters recede during the annual dry seasonand hatchling emergence coincides with the start of the following wet season. This study examined the influence of duration ofimmersion of eggs on hatchling size and hatching success under laboratory conditions. Prolonged immersion of eggs in waterresults in smaller hatchlings and shorter incubation times, but does not increase egg mortality during incubation. Leaching ofcalcium from the eggshell, resulting in reduced availability of calcium to the developing embryo, may explain the smallerhatchlings and shorter incubation period. Hatchlings from thin-shelled eggs, in which shell formation was incomplete, weresmaller and hatched sooner, indicating that the eggshell plays a role in determining hatchling size and incubation period.Thin-shelled and normal eggs had equivalent egg survivorship, indicating that the eggshell is unimportant in egg survivalduring immersion.
Using nonlinear mixed effects models to estimate size-age relationships for black bears
Authors: McRoberts R E , Brooks R T , Rogers L L
Published: April 2011

Sizeage relationships for three physical characteristics, body length, zygomatic width, and pad width, weremodeled for black bears (Ursus americanus) captured in northeastern Minnesota, U.S.A. Because the curves representingsizeage relationships were nonlinear, and because some of the data consist of repeated, longitudinal observations for multiplebears, nonlinear mixed effects model analyses were required. The results are presented as parameter estimates with standarderrors and estimated population curves with 95% confidence intervals. Variance estimates obtained using mixed-effects modelsare compared with erroneous estimates obtained using ordinary least-squares techniques. Comparisons are made between maleand female Minnesota bears with respect to parameter estimates and estimated population curves. In addition, the results forMinnesota bears are compared with results from similar studies on bears in other regions.
Male antler flies (Protopiophila litigata; Diptera: Piophilidae) are more selective than females in mate choice
Authors: Bonduriansky Russell , Brooks Ronald J
Published: April 2011

We investigated mate choice in the antler fly (Protopiophila litigata Bonduriansky), which forms mating aggregations and oviposits exclusively on discarded cervid antlers, by pairing males with nongravid females and by collecting copulating pairs on antlers. Because females probably receive larger ejaculates (which they partly ingest after mating) and more effective protection (mate guarding) from large males than from small ones, we expected females to prefer large males as mates. Because males experience high mating costs and often encounter females lacking mature eggs, we expected males to reject some females. Moreover, because relative abdomen width (fatness) predicts the number of mature eggs (egg load) of a female better than her body size does, we expected males to evaluate female quality by assessing female fatness. Of the 54 male-female pairings, 7 (13%) resulted in copulation, the female rejected the male in 6 (11%), and the male rejected the female in 41 (76%). We found no significant differences between individuals that mated and those that did not. However, females disproportionately rejected males smaller than themselves. Males exhibited a preference (quantified as duration of abdominal tapping bouts) for fat females as mates. Small males appeared to be less choosy than large males. Because males rejected potential mates more frequently than females (apparently) did, males may have been choosier than females. Coupled pairs collected on antlers exhibited positive assortment by body size and positive correlation of male body size with female egg load. These mate-choice and mating-assortment patterns may occur in many dipteran species, where copulation is costly for both sexes, females often lack mature eggs, and mating is initiated in dense aggregations of aggressive males.
Repeat swimming performance of mature sockeye salmon following a brief recovery period: a proposed measure of fish health and water quality
Authors: Jain K E , Birtwell I K , Farrell A P
Published: April 2011

Measurements of swimming ability, such as critical swimming speed (Ucrit), have commonly been used as indicators of the effects of environmental challenges on the general health of fish. In this study, we introduce repeat swimming performance as a particularly sensitive means to assess fish health and the effects of environmental stressors. Adult sockeye salmon (Oncorhynchus nerka) performed two Ucrit tests separated by a 40-min recovery period. When recovery ability was expressed as a ratio of Ucrit values in the first and second swim challenges (Ucrit,2/Ucrit,1), control fish exhibited recovery ratios of unity (0.98 ± 0.01 (mean ± SEM)). In contrast, the recovery of fish pre-exposed to between 0.12 and 0.77 mg·L-1 dehydroabietic acid (DHA) for 8-14 h, and swimming in either hypoxia or normoxia, was impaired. These fish had recovery ratios significantly lower than unity (0.92 ± 0.02) despite swimming to a similar initial Ucrit as control fish. The effect of pre-exposure to DHA was also evident in measurements of oxygen consumption and plasma lactate concentration. Unhealthy fish exhibited significantly lower initial and second Ucrit values than control fish. To account for the low initial swimming performance of these fish, a normalized recovery ratio was introduced ((Ucrit,1/Ucrit,1(control) + Ucrit,2/Ucrit,1)/2). This index of recovery (0.65 ± 0.08) identified the poor physical status of these fish.
Correlates of seasonal changes in metabolism in Atlantic harbour seals (Phoca vitulina concolor)
Authors: Rosen D A , Renouf D
Published: April 2011

This study tested the hypothesis that seasonal variation in resting metabolic rate (RMR) was more closely related to changes in total energy use than to energy intake. It also quantified the extent to which variation in metabolism contributed to changes in total energy expenditure. RMR, gross energy intake, and body mass and composition were measured in six captive Atlantic harbour seals (Phoca vitulina concolor) over 16 months. Gross energy intake during the year (across all seals) averaged 25.4 ± 4.1 MJ/d (mean ± SD). The energy used by the seals Eused a composite measure of energy expenditure from ingested energy and tissue catabolism) averaged 19.2 ± 3.4 MJ/d. RMR averaged 11.2 ± 1.5 MJ/d during the year, while mass-corrected metabolism declined with age. The seals displayed significant changes in both absolute and mass-corrected metabolism during the year. Overall, Eused was a stronger predictor of changes in metabolism than either gross energy intake or body mass. Mass-corrected metabolic rate was more closely related to Eused than was absolute metabolism. Energy changes in metabolism during the year (range = 6.9 ± 1.9 MJ/d) were minor compared with those in Eused (27.8 ± 7.3 MJ/d). These results suggest that seasonal changes in metabolism were a response to, or facilitated by, concurrent changes in Eused but were not the cause of variation in Eused. Rather, variation in both RMR and Eused was the result of changes in other bioenergetic components of the seals' energy budget, such as activity.
Wolf predation in a multiple-ungulate system in northern British Columbia
Authors: Bergerud A T , Elliott J P
Published: April 2011

Caribou (Rangifer tarandus), elk (Cervus canadensis), moose (Alces alces), and Stone's sheep (Ovis dalli stonei) were either decreasing or stable in numbers in two areas in northeastern British Columbia in 1981-1982, prior to reductions in wolf (Canis lupus) numbers. Following the reduction of wolf numbers, recruitment improved 2-5 times for all four species, and all populations increased, based on either hunting statistics, census results, and (or) recruitments greater than 24 offspring at 9 months of age per 100 females. Recruitment of offspring at 9 months of age, when regressed against wolf numbers, declined with decelerating slopes for all four species. This inverse functional response is hypothesized to result from the preparturient spacing of females to reduce predation risk, and in this regard moose seem the least secure and sheep the most effectively spaced. For the four species, mean recruitment at 9 months of age that balanced adult mortality and provided a finite rate of increase of 1.00 was 24.16 ± 0.91 offspring/100 females (n = 11, coefficient of variation = 12.5%). The predicted recruitment rate for all four species in the absence of wolves was 53-57 offspring/100 females. But the birth rate of moose was much higher than those of the other species, indicating greater loss to other factors of which bear predation may be the greatest. Following wolf reductions of 60-86% of entire travelling packs, the wolves quickly recolonized the removal zones, with rates of increase ranging from 1.5 to 5.6.
Revision of the life history of the High Arctic moth Gynaephora groenlandica (Wocke) (Lepidoptera: Lymantriidae)
Authors: Morewood W Dean , Ring Richard A
Published: April 2011

Many studies have explored the adaptations of arctic and alpine Gynaephora species (Lepidoptera: Lymantriidae) to their environment, and base-line life-history information is important for the interpretation of such studies. Data and observations on G. groenlandica (Wocke) collected in recent years at Alexandra Fiord, Ellesmere Island, Canada, contradict some of the life-history information previously published for this species from the same site. Detailed analysis of larval head capsule widths and consideration of growth ratios indicate that there are seven rather than six larval instars and that the pattern of development does not deviate significantly from that defined by the Brooks-Dyar rule. Field-rearing of larvae indicates that first-instar larvae overwinter, while field- and laboratory-rearing both indicate that larvae moult once per year, every year. These data and observations greatly shorten and simplify the life history from that previously published and suggest a life cycle of 7 rather than 14 years. This revised life cycle is not presented as an absolute, in recognition of the potential for individual variation, but rather as typical of the developmental pattern of most of the population. As such, it should provide a useful base line for further studies, especially those addressing the influence of predicted climate change in the Arctic.
Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters
Authors: Ford John KB , Ellis Graeme M , Barrett-Lennard Lance G , Morton Alexandra B , Palm Rod S , Balcomb III Kenneth C
Published: April 2011

Two forms of killer whale (Orcinus orca), resident and transient, occur sympatrically in coastal waters of British Columbia, Washington State, and southeastern Alaska. The two forms do not mix, and differ in seasonal distribution, social structure, and behaviour. These distinctions have been attributed to apparent differences in diet, although no comprehensive comparative analysis of the diets of the two forms had been undertaken. Here we present such an analysis, based on field observations of predation and on the stomach contents of stranded killer whales collected over a 20-year period. In total, 22 species of fish and 1 species of squid were documented in the diet of resident-type killer whales; 12 of these are previously unrecorded as prey of O. orca. Despite the diversity of fish species taken, resident whales have a clear preference for salmon prey. In field observations of feeding, 96% of fish taken were salmonids. Six species of salmonids were identified from prey fragments, with chinook salmon (Oncorhynchus tshawytscha) being the most common. The stomach contents of stranded residents also indicated a preference for chinook salmon. On rare occasions, resident whales were seen to harass marine mammals, but no kills were confirmed and no mammalian remains were found in the stomachs of stranded residents. Transient killer whales were observed to prey only on pinnipeds, cetaceans, and seabirds. Six mammal species were taken, with over half of observed attacks involving harbour seals (Phoca vitulina). Seabirds do not appear to represent a significant prey resource. This study thus reveals the existence of strikingly divergent prey preferences of resident and transient killer whales, which are reflected in distinctive foraging strategies and related sociobiological traits of these sympatric populations.
Effect of microgravity on the development of embryos/larvae and the larval esophageal musculature of the purple starfish, Pisaster ochraceus
Authors: Crawford B J , Martin A C
Published: April 2011

Early gastrula stage embryos of the purple starfish, Pisaster ochraceus, were raised for 10 days in microgravity (µG) in an Aquatic Research Facility aboard the space shuttle Endeavour (STS 77). Controls consisted of embryos raised at 1 × g (1G) in flight and embryos raised at 1G on the ground. Experimental organisms and controls were fixed on mission days (MD) 3, 4, 5, 6, and 7 and one sample was returned alive. Comparison of the µG embryos with the 1G in-flight controls and ground controls suggests that there is little difference in size and overall development. Scanning electron microscopic examination of the development of the esophageal musculature showed that the pattern of development and differentiation was normal and was the same in both the in-flight and ground controls. The esophageal muscle cells of specimens returned alive after 10 days in µG contracted normally. Detailed transmission electron microscopic examination of MD 7 embryos revealed a decreased amount of sarcoplasmic reticulum in the µG embryos compared with both MD 7 1G in-flight and ground controls. These results suggest that while exposure to µG may slow muscle differentiation slightly, it has little overall effect on embryos/larvae of up to 7-8 days of development.
Internesting intervals for loggerhead turtles, Caretta caretta, and green turtles, Chelonia mydas, are affected by temperature
Authors: Sato Katsufumi , Matsuzawa Yoshimasa , Tanaka Hideji , Bando Takeharu , Minamikawa Shingo , Sakamoto Wataru , Naito Yasuhiko
Published: April 2011

To investigate the influence of temperature on the length of internesting periods in loggerhead turtles (Caretta caretta) and green turtles (Chelonia mydas), body temperature and water temperature and depth for free-ranging turtles were monitored during internesting periods using micro data loggers. Body mass and clutch size were also measured. The experiments were conducted at nesting beaches in the Japanese archipelago from 1989 through 1996. Internesting interval was significantly negatively correlated with mean body temperature and mean water temperature. Internesting intervals for some turtles exceeded 21 d when they experienced low water temperatures. Arrhenius' equation was used to describe the quantitative relationships, and Q10 values of 3.1 for water temperature and 3.4 for body temperature were calculated. There was no significant relationship between either clutch size or body mass and internesting interval. Body temperatures were kept higher than water temperatures throughout internesting periods, and larger turtles showed a higher mean thermal difference between body temperature and water temperature. The internesting interval could be considered an egg-maturation period for the next oviposition. The rate of pre-ovipositional development of eggs seemed to be accelerated by high body temperature and decelerated by low body temperature.
Parasitism by Brown-headed Cowbirds and productivity of House Finch hosts
Authors: Kozlovic Daniel R
Published: April 2011

The effect of parasitism by Brown-headed Cowbirds (Molothrus ater) on the reproductive success of a recently established population of House Finches (Carpodacus mexicanus) was studied at St. Catharines, Ontario, during 1983-1985. House Finches began to colonize Ontario in 1972 and breeding was first observed there in 1978. Cowbirds laid in 40.2% of House Finch nests and parasitism was most prevalent during the peak of House Finch nesting. Clutches initiated early in the season were free of cowbird eggs. Most (76%) House Finch nests were parasitized within 2 days after the first House Finch egg was laid. Parasitized House Finch nests contained 1-3 cowbird eggs and the mean number of cowbird eggs per parasitized nest was 1.30. Frequency of multiple parasitism was 24.2% and the number of cowbird eggs per nest was not significantly different from a truncated Poisson distribution. Cowbird parasitism depressed House Finch clutch size and number of hatchlings and fledglings, but the proportion of surviving eggs in parasitized nests that yielded hatchlings and fledglings was not influenced by parasitism. Overall growth of House Finch nestlings did not differ significantly between parasitized and unparasitized nests. Thus, House Finches were able to successfully rear most of their young irrespective of parasitism. The decrease in reproductive output of House Finches was mainly due to egg removal by cowbirds, which effectively reduced the clutch size of parasitized nests by about 1 House Finch egg.
Cone spectral sensitivity in the harbor seal (Phoca vitulina) and implications for color vision
Authors: Crognale Michael A , Levenson David H , Ponganis Paul J , Deegan II Jess F , Jacobs Gerald H
Published: April 2011

The retinas of harbor seals (Phoca vitulina) contain two morphologically distinct photoreceptor types: rods and cones. The spectral properties of the cones have not been previously studied. The spectral sensitivities of the cones of harbor seals were measured using a retinal gross potential technique, flicker photometric electroretinography. We found a cone spectral sensitivity curve with a peak at about 510 nm. The shape of the spectral sensitivity curve remained invariant despite large changes in chromatic adaptation, implying that harbor seals have only a single cone photopigment. This means that harbor seals must lack color vision at photopic light levels. Any color discrimination in this species would have to be based on combined input from rods and cones and thus restricted to mesopic light levels. The spectral sensitivity of the cone pigment in the harbor seal is shifted to shorter wavelengths than those of terrestrial carnivores, consistent with adaptation to the aquatic photic environment.
Urinary 3-methylhistidine and progressive winter undernutrition in white-tailed deer
Authors: DelGiudice Glenn D , Kerr Ken D , Mech L David , Riggs Michael R , Seal Ulysses S
Published: April 2011

Physiological indicators of muscle catabolism would aid assessment of winter nutritional restriction of ungulates, and urinary 3-methylhistidine has exhibited potential in this regard in several species. We examined the effect of chronic moderate and severe nutritional restriction during winter on urinary 3-methylhistidine:creatinine ratios in seven adult white-tailed deer (Odocoileus virginianus) and the relationship of these ratios to urinary urea nitrogen:creatinine ratios. Mean base line estimates of urinary 3-methylhistidine:creatinine ratio for the control and severely restricted deer (0.043 and 0.086 µmol:mg, respectively) were similar (P = 0.280) and remained unchanged in the control deer throughout the study. In contrast, mean 3-methylhistidine:creatinine ratios increased dramatically as nutritional restriction and cumulative mass loss progressed; the quadratic component of the data for the chronically restricted deer was significant (P < 0.001). Likewise, there was a strong curvilinear relationship (R2 = 0.82) between cumulative mass loss (up to 29%) of the pooled deer and urinary 3-methylhistidine:creatinine ratios. Further, urinary urea nitrogen:creatinine ratios were strongly related to 3-methylhistidine:creatinine ratios (r2 = 0.89). Our study indicates that further investigation of 3-methylhistidine as an indicator of physical condition and muscle protein breakdown is warranted.
Geographic and seasonal variation in biological characteristics of American eel elvers in the Bay of Fundy area and on the Atlantic coast of Nova Scotia
Authors: Jessop B M
Published: April 2011

Seasonal (April-July) patterns in the decline of length, mass, and condition and an increase in pigmentation stage of American eel (Anguilla rostrata) elvers collected during the estuarine commercial fishery and during entrance into fresh water varied among rivers in the Bay of Fundy and on the Atlantic coast of Nova Scotia. Elver mean length, adjusted to a mean collection date, varied among commercially fished rivers by up to 9%; mean mass varied by up to 27%. Within commercially fished rivers, mean length declined seasonally by 2-5%, mass by 0-60%, and condition by 0-44%. Elver condition declined 7-9% by the time 50% of the run (number of elvers) had entered the East River, Chester, and East River, Sheet Harbour, and by 21% at 95% of the run, while the mean pigmentation stage increased to 4.1-4.8 and 5.7-6.5, respectively, on a scale of 1-7. Such geographic variability in biological traits may result from the effect of varying annual and seasonal environmental conditions on the coastal distribution of elvers and on their run timing and physiological development in estuarine and stream habitats. The biological importance of the seasonal decline in elver length, mass, and condition is uncertain, but a seasonal decline in mass of 35% may be commercially important when elvers are sold by weight rather than count.
The perching bird Coereba flaveola as a co-pollinator of bromeliad flowers in southeastern Brazil
Authors: Sazima Marlies , Sazima Ivan
Published: April 2011

Hummingbirds are the only previously recorded bird pollinators of ornithophilous bromeliads in southeastern Brazil. We studied the pollination of three species of Bromelioideae by the Bananaquit Coereba flaveola, a perching bird. Flowers of the bromeliads Aechmea bromeliifolia, Aechmea distichantha, and Acanthostachys strobilacea are visited by this perching bird, as well as by hummingbirds. The Bananaquit perches on the inflorescences and probes within the narrow corolla with its slender bill, fully opening the flower in order to reach the nectar. Although they look somewhat "plundered," the flowers visited by the Bananaquit are pollinated during its periodic visits to the plants.
Association patterns in three populations of Hector's dolphin, Cephalorhynchus hectori
Authors: Bräger Stefan
Published: April 2011

Most delphinids are very social and spend much time in the presence of conspecifics. The proportion of co-occurrences of any two individuals is usually measured by means of association indices. In this study, the "half-weight index" was used to describe the association patterns in three previously unstudied populations of Hector's dolphin, Cephalorhynchus hectori, around the South Island of New Zealand. For inclusion in this analysis individuals were photoidentified repeatedly over a 2-year study period. Only about 1% of the individual associations of dolphin pairs (dyads) tested were found to be significantly different (p less than or equal to 0.01) from random distributions derived from a new constrained Monte Carlo randomisation. The overall association patterns in the two study populations off Kaikoura ( n = 48 individuals) and Moeraki (n = 24) did not differ significantly from what could be expected by chance (p = 0.07 and 0.09, respectively), whereas those in the Jackson Bay population (n = 38) were significantly different from chance (p < 0.0002). Hector's dolphins appear to have a typical fission-fusion society, with many weak associations within the wider envelope of the local population.
Restriction fragment length polymorphism of rDNA in the redfishes Sebastes fasciatus and S. mentella (Scorpaenidae) from the Gulf of St. Lawrence
Authors: Desrosiers B , Sévigny J -M , Chanut J -P
Published: April 2011

A restriction fragment length polymorphism (RFLP) analysis was carried out on nuclear ribosomal DNA (rDNA) of the redfishes Sebastes fasciatus and Sebastes mentella from the Gulf of St. Lawrence in an attempt to describe new molecular markers that would discriminate these two sibling species. The RFLP analysis revealed heterogeneity in the size of the repeat unit within and among individuals that is most likely the result of variation in the length of the intergenic spacer. Double digestion of rDNA with the restriction enzymes EcoRI and ScaI and subsequent hybridization with a 28S probe revealed the presence of three patterns of fragments. Two fragment groups seem to characterize S. mentella and S. fasciatus. Both fragment groups were present in several specimens, suggesting either a restriction-site polymorphism in S. mentella or a hybrid origin for these redfish. Discriminant analysis clearly differentiated all three rDNA patterns. Comparisons of genetic variations at the MDH* locus and of the number of soft rays in the anal fin among the three rDNA-defined groups suggest that if the individuals showing the two groups of fragments are hybrids between S. fasciatus and S. mentella, introgression has also occurred in the Gulf of St. Lawrence.
Changes in pituitary, ovarian, and testicular activity in harbour seals (Phoca vitulina) in relation to season and sexual maturity
Authors: Gardiner K J , Boyd I L , Follett B K , Racey P A , Reijnders P JH
Published: April 2011

This study examined pituitary sensitivity to exogenous gonadotrophin-releasing hormone (GnRH) in relation to time of year and changes in plasma progesterone, testosterone, luteinising hormone (LH), and follicle-stimulating hormone (FSH) concentrations during the annual cycle of adult and juvenile harbour seals (Phoca vitulina vitulina). There was no significant difference in seasonal changes in reproductive hormone levels between six captive individuals and seals caught from the wild (n = 80). Based on results from both the captive and the wild individuals, the plasma progesterone concentration was elevated in late gestation, whereas it declined at the equivalent time in nonpregnant females. The progesterone concentration was also elevated during the phase of delayed implantation, but there was no difference between pregnant and nonpregnant seals. In captive seals given exogenous GnRH, the LH concentration peaked 10-20 min after injection of GnRH, and the magnitude of the LH response depended upon the dose up to ~120 ng·kg-1. FSH did not respond to GnRH in the time course of the experiment. Pituitary sensitivity to GnRH was greatest in the summer and autumn and lowest in the winter and spring. Seasonal changes in pituitary sensitivity were apparent in both adults and juveniles. There was evidence that three of the four juvenile seals attained puberty during the study. We conclude that the seasonal patterns of pituitary sensitivity and plasma hormone concentration in harbour seals are consistent with a reproductive cycle under photoperiodic control and with the general mechanisms underlying photoperiodic control of seasonal reproduction in higher vertebrates.
Growth factors reverse developmental arrest by zinc in embryos of the sea urchinHemicentrotus pulcherrimus
Authors: Kinoshita Tsutomu
Published: April 2011

During sea urchin development, zinc (Zn) ions produce developmentally arrested embryos called permanent blastulae. In this study, the effects of growth factors on Zn-arrested embryos were examined to elucidate the relation between Zn arrest and morphogenesis that is mediated by growth factors. Embryos treated with Zn maintained their spherical form for a few days in the absence of growth factors. When the culture medium was supplemented with horse serum, gastrulation occurred in the Zn-arrested embryos, some of which developed into symmetrical larvae closely resembling normal plutei. The growth factors basic fibroblast growth factor (bFGF), TGF-β1, TGF-β2, and activin A also induced recovery of the Zn-arrested embryos. Of the four growth factors tested, activin showed the most intense activity and allowed development of a radial larva with a thick ciliated band and a partially invaginated archenteron. Histochemical staining with ALPase demonstrated the formation of a morphologically and functionally mature digestive tract in the activin-treated embryos. Immunofluorescent staining showed that spicules formed within the msp130-positive mesenchyme cells in the activin-treated embryos. Reversal of Zn arrest did not occur in embryos cultured with serum albumin. These results suggest that Zn arrests development by inhibiting the initiation of morphogenesis and this is mediated by peptide growth factors.
Fat deposition and seasonal variation in body composition of red foxes (Vulpes vulpes) in Australia
Authors: Winstanley Roy K , Buttemer William A , Saunders Glen
Published: April 2011

We evaluated body composition of 165 adult red foxes (Vulpes vulpes) collected monthly from August 1995 to July 1996 in New South Wales, Australia. Total body fat content and estimated protein content were determined as a percentage of skinned body mass (SBM) using chemical analysis of homogenized samples. Mean percent body fat varied significantly over the year (P < 0.001) and differed significantly between the sexes in each month (P = 0.039). Male body fat reserves peaked at 13% of SBM in June, prior to breeding, and female body fat peaked at 16% of SBM in July during gestation. Body fat reserves declined rapidly in both sexes from September through November, reaching average values of 3-4% SBM by the time of weaning (November). Estimates of total body protein content varied significantly over the year (P < 0.001) but did not differ significantly between the sexes (P = 0.745). Protein content was lowest but stable at 21-22% of SBM from August to November and increased rapidly by December. Protein content then remained stable at 23-25% of SBM from January through July. The low body protein content in August through November corresponds to the decline in body fat reserves of foxes. These foxes appear to accumulate fat and protein reserves throughout the non-reproductive phase of their annual cycle and then deplete these stores during their reproductive period.
Predicting the wolf-prey equilibrium point
Authors: Eberhardt L L , Peterson R O
Published: April 2011

Difference equation models of wolf and ungulate prey populations were used to estimate the presumed equilibrium ratio by regression of the finite rate of increase of wolf (Canis lupus) populations against wolves per 1000 deer-equivalents of biomass in the prey populations. Further assessment of ratios derived directly from estimates of wolf and prey abundance indicated that such ratios probably substantially overestimate the equilibrium value. This prospect is illustrated by data from Isle Royale. The best present estimate of the equilibrium ratio is 122 deer-equivalents per wolf, a value which indicates that the substantial reductions in moose (Alces alces) populations through predation which has been suggested may be correct. Our results indicate that two-state equilibrium models may not be needed to describe wolf-ungulate equilibria.
Selection of natal dens by the swift fox (Vulpes velox) on the Canadian prairies
Authors: Pruss Shelley D
Published: April 2011

The location and physical characteristics of 32 occupied swift fox (Vulpes velox) natal/rearing dens and 33 unoccupied sites in southeastern Alberta and southwestern Saskatchewan, Canada, were compared in 1991 and 1992. Comparisons between occupied and unoccupied sites were restricted to eight habitat variables that described the orientation of each den entrance, mean height of old and new grass, number of holes in each den complex, den position and slope (i.e., incline of the land) in relation to hills, and distance to the nearest roadway and water source. Two-sample t tests and Mann-Whitney U tests indicated that occupied sites were located on the tops of hills, close to roads, and in places where old grass was significantly higher than at unoccupied sites. Den entrance angles did not differ between occupied and unoccupied sites. A stepwise discriminant function analysis identified five potential discriminators of occupied and unoccupied sites (i.e., position on a hill, height of new grass, distance to water, distance to roads, and slope). Den position was the variable that discriminated most strongly between occupied and unoccupied sites. Occupied sites were located predominantly on the tops of hills. The quadratic discriminant function had an overall classification success of 83.1%. Based on the five habitat variables, the discriminant function model correctly classified 28 of the 32 occupied sites as being occupied (87.5%) and 26 of the 33 unoccupied sites as being unoccupied (78.8%). The habitat variables identified by the discriminant function model may be a useful tool for selecting and modifying release-site characteristics and creating more realistic live-rearing facilities.
Population dynamics of kit foxes
Authors: White P J , Garrott Robert A
Published: April 2011

We evaluated data from field studies of kit foxes to identify factors that strongly influence or regulate their population dynamics. Two density-dependent regulating mechanisms were detected. First, the rate of juvenile recruitment was inversely related to the density of adult foxes because a higher proportion of juveniles were killed by coyotes at higher fox densities. The mortality rates of adult foxes were independent of population density. Second, populations of kit foxes are bounded by their territorial spacing behavior, which limits recruitment at high densities. These regulatory factors may operate in concert to curtail population growth at high densities, whereas decreased juvenile mortality by coyotes can operate independently to increase population growth at low densities. Despite the presence of these strong regulating factors, density-independent variations in reproductive rates often result in population crashes or irruptions that are the fundamental causes of instability in populations of kit foxes. Desert systems are characterized by unpredictable fluctuations in precipitation, which contribute to high-frequency, high-amplitude fluctuations in the abundance of mammalian prey (leporids, rodents) for kit foxes. These fluctuations subsequently contribute to density-independent variations in fox reproductive rates, which are strongly influenced by food supply. Projection models of a kit fox population showed that unpredictable, short-term fluctuations in precipitation and, in turn, prey abundance could generate longer term, aperiodic fluctuations in the density of foxes. Consequently, high amplitude fluctuations in the abundance of kit foxes may be intrinsic to the desert systems that they inhabit and need not reflect special or persistent causes such as predation or disease.
Two karyotypes and heteromorphic sex chromosomes in Physalaemus petersi (Anura, Leptodactylidae)
Authors: Lourenço Luciana B , Recco-Pimentel Shirlei M , Cardoso Adão J
Published: April 2011

Cytogenetic analyses were performed on specimens from two populations of Physalaemus petersi from three locations in Brazilian West Amazon. Chromosomes from the testis and intestinal epithelium were stained conventionally with Giemsa or C-banded. All animals studied showed a full chromosome complement of 2n = 22, but two distinct karyotypes (I and II) were detected among specimens from one of the populations. Karyotype I specimens showed a XX/XY sex chromosome system and C-band polymorphism. Bivalent chromosomes with heterozygous C-banding frequently lacked chiasmata in the region of this heterochromatin during the first meiotic division. The less common karyotype (II) had a heteromorphic pair of chromosomes, but the relationship of this pair to sex determination could not be elucidated because of the absence of female specimens. Karyotype II was observed in males whose call differed from those of other males in the same population, suggesting that a reevaluation of the taxon P. petersi may be necessary. These results suggest that, in these populations, karyological evolution occurs faster than anatomical evolution.
Phylogeny of the central-western Pacific subgenus Inseliellum (Diptera: Simuliidae)
Authors: Craig D A , Currie D C
Published: April 2011

Subgenus-level groups of western and central Pacific Simuliidae are briefly assessed using phylogenetic principles. Inseliellum and Nevermannia (ruficorne-group) are established as sister taxa. Detailed morphological analysis of 32 species of Inseliellum shows that the Micronesian Simulium trukense is the basal lineage. Austral and Cook islands species, plus those of the Marquesas Islands, form the next basal clade. Simulium malardei is the sister taxon of all other Society Islands species, including Simulium adamsoni from the Marquesas Islands. There are three clades: the tahitiense-group, which is weakly supported, the castaneum-group, which is moderately well supported, and the oviceps-group, which is strongly supported. One of two most parsimonious phylogenies that is in agreement with independent cytological information is presented. Habitat preference and larval behaviour are optimized on this phylogeny, providing information about evolutionary trends. Brief comments are made regarding geological development of the habitats of larvae of some species.
Blood oxygen requirements in resting crab (Carcinus maenas) 24 h after feeding
Authors: Legeay Alexia , Massabuau Jean-Charles
Published: April 2011

Numerous resting unfed water-breathers have a strategy of gas-exchange regulation that consists of setting the arterial partial pressure of oxygen (Pao2) at 1-3 kPa. This raises a question concerning the extent to which physiological functions are limited in this situation. To obtain insight into this problem, we studied the steady-state adaptation of the blood-oxygen transfer system in the crab Carcinus maenas during the doubling of the oxygen consumption rate, Mo2(i.e., during the period of specific dynamic action of food (SDA)), that occurs 24 h after feeding. We showed that this increase in the oxygen consumption rate 24 h after a meal is not limited by a blood partial pressure of oxygen (Po2) as low as 0.8-1.5 kPa in either normoxia or hypoxia (Po2of the inspired water = 4 kPa). In normoxia, adaptation of the oxygen-transport system, if any, consisted of a combined set of adaptations of small amplitude (in absolute value), rather than major changes in blood oxygenation status, blood flow rate, or oxygen affinity (although blood pH decreases). In hypoxia, the SDA was mainly associated with an increase in blood flow rate and blood pH, with no changes in blood lactate, urate, calcium, and haemocyanin concentrations. The results are discussed, in an environmental context, in terms of minimal oxygen requirements in water-breathers.
Habitat selection by roe deer and sheep: does habitat ranking reflect resource availability?
Authors: Mysterud Atle , Larsen Per Kristian , Ims Rolf Anker , Østbye Eivind
Published: April 2011

Habitat ranking is often assumed to reflect food availability, but habitat selection may involve trade-offs, for example, between selecting for food or cover. We tested whether the habitat selection of 27 radio-collared European roe deer (Capreolus capreolus) and 10 free-ranging domestic sheep (Ovis aries) on a forest range in southern Norway reflected resource availability. We predicted that ruminants of different feeding types would use habitats according to the main forage class, but that antipredator behavior might remove the correlation between habitat selection and food availability, thus making temporal and spatial scaling crucial. As predicted, habitat selection by sheep was highly correlated with grass availability on both the home-range and study-area scales. The habitat ranking of roe deer habitat selection did not correlate with the availability of herbs on either scale, but rather was correlated with the availability of canopy cover. We found a clear effect of temporal scale on habitat selection by roe deer. During summer, roe deer used forest habitats with more forage to a greater extent when they were active than when they were inactive, and tended to use habitats with greater availability of herbs at night. We conclude that scale-dependent trade-offs in habitat selection may cause inconsistent habitat rankings when pooled across temporal and spatial scales.
Costs associated with leg autotomy in the harvestmenLeiobunum nigripesandLeiobunum vittatum(Arachnida: Opiliones)
Authors: Guffey Cary
Published: April 2011

The benefits of autotomy of appendages are usually obvious but the costs are often less apparent. This study reports the effects of leg autotomy on mobility, foraging ability, and sensory perception in two species of harvestmen, Leiobunum nigripes and Leiobunum vittatum (Opiliones: Sclerosomatidae). The running speed of both species was recorded in a test track. Individuals of both species with only 5 legs were significantly slower than those with 6 or more legs. The mobility and foraging abilities of L. nigripes were tested by recording the time it took for them to find and eat chilled flies (Drosophila virilis). Those harvestmen with only 5 legs spent significantly less time moving and foraging than did those with more legs and took significantly longer to find food than did those with 7 or 8 legs. These results indicate that significant reductions of mobility and foraging ability occur only after the loss of 3 or more legs. Also, flies were eaten significantly sooner after contact with either of the first legs than after contact with the second legs, suggesting that the first pair of legs is more important in identifying food than had been indicated previously in the literature.
Unexpected offspring sex ratios in response to habitat quality in a size-dimorphic bark beetle
Authors: Sargent Risa D , Reid Mary L
Published: April 2011

Facultative sex ratio manipulation has been examined in a limited number of diploid species, mainly vertebrates. We tested the prediction that mothers would preferentially place males in conditions conducive to large size in the diploid pine engraver bark beetle, Ips pini. In this species, males are the larger sex and therefore male reproductive success was expected to be more dependent on body size than female reproductive success. Because body size is largely environmentally determined in bark beetles, mothers were expected to alter sex ratios in response to habitat quality. Contrary to predictions, offspring sex ratios tended to be more female biased in situations conducive to large offspring size than in situations producing offspring of small size. We were able to rule out nonadaptive explanations such as differential mortality or development times of males and females, suggesting that the observed pattern is adaptive. This study provides a rare example of sex ratio manipulation in diploid insects. However, the unexpected direction of sex ratio biases suggests that daughters gain a yet unknown benefit from being reared in high-quality conditions that surpasses the fitness that would be gained from producing relatively larger sons.